Note: Descriptions are shown in the official language in which they were submitted.
CA 02576337 2007-01-25
METHOD, APPARATUS AND NUT FOR PRELOADING A BEARING
TECHNICAL FIELD
[0001] The present invention relates, generally, to methods and apparatus for
preloading antifriction bearings in drive trains, particularly, to preloading
and adjusting
bearings while monitoring the preload being applied.
BACKGROUND OF THE INVENTION
[0002] Various means have been devised to simplify the adjustment of axle
bearings,
specifically, truck axle bearings. It is generally accepted that in some
bearing
installations, for example, axle bearings, the life of the bearing will be
optimized if the
adjustment is made for a slight axial compressive deflection, for example,
about
0.003 inches (where this amount is the compressive deflection of the two
bearings
combined), which is often referred to as" a three thousandths preload."
Typical prior art
methods of creating these preloads are obtained by applying specified torques
to the
bearing assembly, for example, by tightening the nut that retains the
bearings. However,
for several reasons, it is typically extremely difficult to achieve such
preload settings
under actual in-field conditions, as in a mechanic shop. For example, the
assembly of a
heavy truck wheel onto a wheel hub assembly is a relatively cumbersome
procedure that
hinders the mechanic. Moreover, the wheel hub assembly always includes at
least one
inner seal, usually a lip type of seal, which can impose a resistive drag
torque component
to the preload torque, particularly when the seal is new.
[0003] One of the popular means of adjusting bearing preload by means of an
applied
torque is described in the literature provided by the Stemco Company, of
Longview,
Texas (for example, Stemco form 571-2970) and further in instructions provided
by
Stemco (for example, Stemco part number 09-571-0006). These instructions are
typically packaged with Stemco's axle spindle nuts. The accuracy of this and
other prior
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art preloading methods is limited because they rely on the relationship
between assembly
torque and axial preload of the bearings, which will vary with variations in
torsional
resistance or friction of the nut against the face of the bearing, and will
also vary with
variations in torsional resistance or friction of the nut against the spindle
thread, the nut
against the bearing face, and the aforementioned lip seal present in the
assembly.
[0004] Due to the limitations and disadvantages of these and other prior art
bearing
preloading methods and devices, there is a need to provide accurate and
repeatable
procedures and devices for providing and adjusting bearing preload. Aspects of
the
present invention overcome the limitations and disadvantages of the prior art
and provide
methods and apparatus for creating known, monitorable, uniform preload that is
not
subject to the inaccuracies of prior art methods and devices. Moreover,
aspects of the
present invention are easier to apply by a mechanic.
SUMMARY OF THE INVENTION
100051 The present invention provides improved methods and apparatus for
preloading
bearings. In particular, the methods and apparatus of the present invention
permit the
mechanic to monitor the preload during the preloading procedure to more
accurately
determine the actual preload provided. One aspect of the invention is an
apparatus for
providing a preload on a bearing, the bearing having an inner race mounted to
a shaft and
an outer race mounted in a hub, the apparatus including a rod having a first
end and a
second end adapted to be removably mounted to the shaft; means for compressing
the
hub against the outer race of the bearing to provide the preload to the
bearing, the means
for compressing mounted to the rod; and a cylindrical frame positioned between
the
means for compressing the hub and the hub, the cylindrical frame having a
first end
adapted to receive a load from the means of compressing the hub and a second
end
adapted to transmit the load to the hub. In one aspect, the second end of the
cylindrical
frame contacts the hub. In another aspect, the second end of the cylindrical
frame
contacts an inner race of a bearing. In another aspect, the apparatus further
comprises
means for monitoring the preload on the bearing
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[0006] Another aspect of the invention is a method for providing a preload on
a bearing
having an inner race mounted to a shaft and an outer race mounted in a hub,
the method
including mounting a rod to an end of the shaft; mounting a means for
compressing the
hub against the outer race of the bearing to the rod; and actuating the means
for
compressing the hub to compress the hub against the outer race of the bearing
to provide
the preload to the bearing. In one aspect, the method further comprises
monitoring the
preload on the bearing.
[0007] Another aspect of the invention is an apparatus for providing a preload
to an
inboard bearing having an inner race mounted to a shaft and an outer race
mounted in a
hub and for providing a preload to an outboard bearing having an inner race
mounted to
the shaft and an outer race mounted in the hub, the outboard bearing spaced
from the
inboard bearing, the apparatus including an outboard bearing retaining nut
adapted to
engage a threaded end of the shaft and contact the inner race of the outboard
bearing to
retain the preload on the outboard bearing; a rod having a first end and a
second end
adapted to be removably mounted to the shaft; a fluid-containing cylinder
mounted to the
rod, the cylinder having a cylinder housing mounted to the rod and a piston
adapted to
compress the hub against the outer race of the inboard bearing to provide the
preload to
the inboard bearing; an actuating nut threaded to the rod and adapted to
compress the
cylinder housing toward the piston; and a cylindrical frame positioned between
the piston
and the hub having a first end adapted to receive a load from the piston and a
second end
adapted to transmit the load to the hub and compress the hub against the inner
race of the
inboard bearing to provide the preload to the inboard bearing. In one aspect,
the
apparatus further comprises means for monitoring the pressure of the fluid in
the fluid-
containing cylinder.
[0008] A further aspect of the invention is an apparatus for precisely
rotating a nut, the
apparatus including a guide frame comprising a support ring having a first
side adapted to
contact a support and a second side opposite the first side; and a plurality
of posts having
first ends mounted to the second side of the support ring and second ends
opposite the
first ends; and a tool comprising a set of opposed tines adapted to engage
flats on the nut;
means for rotating the tines to rotate the nut; and at least two spaced stops
adapted to
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engage at least one of the posts of the guide frame and limit the rotation of
the nut to the
predetermined angle defined by the two spaced stops.
[0009] A still further aspect of the invention is a method for precisely
rotating a nut, the
method including determining a desired precise rotation for the nut; providing
a guide
frame comprising: a support plate having a first side adapted to contact a
support and a
second side opposite the first side; and a plurality of spaced stops
positioned on the
support plate; providing a tool comprising: at least one set of opposed tines
adapted to
engage flats on the nut; and a plurality of spaced stops adapted to engage at
least one of
the spaced stops of the guide frame, the spaced stops positioned to limit the
rotation of
the tool to the desired precise rotation for the nut; mounting the tool to the
nut wherein
the plurality of tines engage flats on the nut and wherein the at least one
stop on the tool
engages at least one stop on the guide frame; and rotating the nut with the
tool wherein at
least one stop on the tool engages at least one stop on the guide frame
wherein the nut is
rotated the desired precise rotation.
[0010] A further aspect of the invention is a tool for precisely rotating a
nut, the tool
including: at least one set of opposed tines adapted to engage flats on the
nut; means for
rotating the plurality of tines to rotate the nut; at least one stop adapted
to engage at least
corresponding stop on a fixture mounted adjacent the nut to limit the rotation
of the nut to
a predetermined angle. In one aspect, the at least one stop on the tool
comprises at least
one of a post, pin, and recess.
[0011] A further aspect of the invention is an axle nut comprising a
cylindrical body
having a first end, a second end having a face adapted to bear against a
surface, a
longitudinal axis, and an outer surface engagable by a tool; a threaded
through-hole
directed substantially along the longitudinal axis of the cylindrical body;
and at least one
recess in the face of the second end of the cylindrical body, the at least one
recess adapted
to expose at least a portion of the surface the face bears against. In one
aspect, the at
least one recess comprises at least one arcuate recess, for example, a
plurality of arcuate
recesses equally spaced about the perimeter of the face.
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[0012] Another aspect of the invention is an apparatus for providing a load on
a
bearing, the bearing having an inner race mounted to a shaft and the bearing
retained on
the shaft by a nut, the apparatus comprising a rod having a first end and a
second end
adapted to be removably mounted to the shaft; an adapter comprising a plate
having a
hole through which the rod passes and a plurality of extensions mounted to the
plate and
adapted to engage the inner race of the bearing with the nut in place; and
means for
providing a compressive load to the plate of the adapter whereby the load is
provided to
the inner race of the bearing with the nut in place. In one aspect, the
plurality of
extensions is pivotally mounted to the plate. In another aspect, the apparatus
further
comprises means for monitoring the load on the bearing.
[0013] A further aspect of the invention is a method for providing a load on a
bearing
having an inner race mounted to a shaft and the bearing retained on the shaft
by a nut, the
method comprising mounting a rod to an end of the shaft; without removing the
nut,
mounting a means for compressing the inner race of the bearing to the shaft;
and
actuating the means for compressing the inner race to compress the inner race
to provide
the load to the bearing. In one aspect, the means for compressing the inner
race
comprises an adapter having a plate and a plurality of extensions mounted to
the plate,
wherein mounting the means of compressing comprises mounting the adapter to
the rod
and the inner race.
[0014] A still further aspect of the invention is a fastener arrangement for
retaining a
bearing on a shaft, the bearing having an inner bearing race having an outer
diameter, the
fastener arrangement adapted to permit a bearing loading device to contact the
inner
bearing race, the fastener arrangement comprising a first threaded ring
adapted to
threadably mount to the shaft and engage the inner bearing race, the first
threaded ring
having an outer diameter less than the outer diameter of the inner bearing
race and an
outer surface engagable by a tool; a second ring adapted to mount to the shaft
and
engage the first ring and engage the shaft to prohibit relative movement
between first ring
and the shaft; and a third threaded ring adapted to threadably mount to the
shaft and to
contact the second ring, the third ring having an outer surface engagable by a
tool;
wherein when the first ring, second ring, and third ring are mounted to the
shaft, the
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bearing is retained on the shaft and the inner bearing race is exposed and can
be contacted
by the bearing loading device. In one aspect, at least one of the first
threaded ring and
the third threaded ring comprises a threaded nut.
[0015] An even further aspect of the invention is a method for providing a
load to a
bearing having an inner race mounted to a threaded shaft, the inner race
having an outer
diameter, the method comprising threading a first threaded ring onto the
threaded shaft
whereby the threaded ring contacts the inner bearing race, the first threaded
ring having
an outer diameter less than the outer diameter of the inner; mounting a second
ring to
the shaft, the second ring adapted engage the first ring and engage the shaft
to prohibit
relative movement between first ring and the shaft; and threading a third
threaded ring
on to the shaft, the third threaded ring adapted to engage the second ring;
and engaging
the inner race with an apparatus adapted to provide the load to the inner
race. In one
aspect, the method further comprises monitoring the load on the inner race. In
another
aspect, the method further comprises, when the load on the inner race reaches
about a
predetermined load, tightening the first threaded ring against the inner race,
for example,
to maintain the predetermined load on the inner race.
[0016] These and other aspects, features, and advantages of this invention
will become
apparent from the following detailed description of the various aspects of the
invention
taken in conjunction with the accompanying drawing
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The subject matter, which is regarded as the invention, is particularly
pointed
out and distinctly claimed in the claims at the conclusion of the
specification. The
foregoing and other objects, features, and advantages of the invention will be
readily
understood from the following detailed description of aspects of the invention
taken in
conjunction with the accompanying drawings in which:
[0018] FIGURE 1 is perspective view of a wheel hub assembly having a bearing
preloading apparatus according to one aspect of the invention.
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. ,
[0019] FIGURE 2 is a right side elevation view of the hub assembly shown in
FIGURE 1.
[0020] FIGURE 3 is a right side elevation view, partially in cross section, of
the
assembly shown in FIGURE 1
[0021] FIGURE 4 is a detailed view of the means for providing a preload shown
in
FIGURE 3 and identified by detail 4.
[0022] FIGURE 5 is a partial cross sectional view of another aspect of the
invention for
transferring a load to a bearing.
[0023] FIGURES 6A, 6B, and 6C are partial axial elevation views of another
aspect of
the invention as viewed along the section lines 6-6 shown in FIGURE 4 with the
addition
of a typical tool according to one aspect of the invention.
[0024] FIGURE 7 is a right side elevation view, partially in cross sectional,
of another
aspect of the invention.
[0025] FIGURE 8 is perspective view of a wheel hub assembly having a bearing
preloading apparatus according to another aspect of the invention.
[0026] FIGURE 9 is a right side elevation view of the hub assembly shown in
FIGURE 8.
[0027] FIGURE 10 is a right side elevation view, partially in cross section,
of the
assembly shown in FIGURE 8
[0028] FIGURE 11 is a detailed view of the means for providing a preload shown
in
FIGURE 10 and identified by detail 11.
[0029] FIGURE 12 is perspective view of the bearing loading adapter shown in
FIGURE 11.
[0030] FIGURE 13 is a side elevation view, partially in cross section, of the
bearing
loading adapted shown in FIGURE 12.
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[0031] FIGURE 14 is top plan view of the bearing loading adapter shown in
FIGURE 12.
[0032] FIGURE 15 is a perspective view of an axle nut according to another
aspect of
the invention.
[0033] FIGURE 16 is a side elevation view, partially in cross section, of the
axle nut
shown in FIGURE 15.
[0034] FIGURE 17 is a side elevational view, partially in cross section and
similar to
FIGURE 11, of an apparatus for applying or verifying a preload on a bearing
according to
another aspect of the invention.
[0035] FIGURE 18 is a perspective view, partially in cross section, of a nut
arrangement shown in FIGURE 17 according to another aspect of the invention.
[0036] FIGURE 19 is an exploded perspective view the nut arrangement shown in
FIGURES 17 and 18.
DETAILED DESCRIPTION OF THE INVENTION
[0037] FIGURE 1 is perspective view of a wheel hub assembly 10 having a
bearing
preloading apparatus 20 according to one aspect of the invention. In FIGURE 1,
some of
a section of the hardware has been removed to reveal inner structure to
facilitate
disclosure of the invention. FIGURE 2 is right side elevation view of the
wheel hub
assembly 10 and preload apparatus 20 shown in FIGURE 1. FIGURE 3 is a right
side
elevation view, partially in cross section, of the assembly shown in FIGURE 1.
For the
sake of illustration, the wheel assembly that would typically be mounted to
wheel hub
assembly 10 is omitted. Wheel hub assembly 10 represents a typical wheel hub
that may
be found on any wheeled vehicle, for example, a wheel hub of truck, a front or
rear axle
of a tractor of a tractor-trailer, or an axle of a trailer.
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[0038] The wheel hub assembly 10 shown in FIGURE 1 is an assembly that
would
typically be found on a front or rear axle of a cab or tractor of a tractor-
trailer, or an axle
of a trailer. However, aspects of the invention are not limited to use for
vehicle bearings.
As will generally be understood by those skilled in the art, aspects of the
invention may
be used to service bearings and bearing assemblies in any machine or device
that employs
bearings, including, but not limited to: power trains, transmissions, machine
components,
on and off-road vehicles, aircraft wheels, marine drives, spacecraft, conveyor
rolls, and
windmills, among others. According to aspects of the present invention,
preloading
apparatus 20 may be used in these and any other assembly for which bearing
preload
and/or endplay is desired, for example, any assembly that utilizes thrust and
radial load
carrying bearings that are indirectly mounted.
[0039] As shown in FIGURES 1 and 3, typical wheel hub assembly 10 includes a
wheel hub or, simply, a hub 12, a threaded shaft, axle, or "spindle" 14. As is
typical, on
spindle 14 are mounted two antifriction bearings 16 and 18 and spindle 14
includes an
exposed end 13, which is typically threaded. Spindle 14 typically includes a
retaining
nut 11 threaded to the exposed end 13. Retaining nut 11 may comprise any
available
retaining nut. In the conventional art, retaining nut 11 typically is used to
secure a wheel
(not shown) or hub assembly to a non-rotating axle 14. However, in aspects of
the
present invention, retaining nut 11 may be useful in varying the preload
and/or endplay of
bearings 16 and 18. Though bearings 16 and 18 are illustrated as tapered
roller bearings,
aspects of the invention may be applied to other types of antifriction
bearings for which it
is desirable to provide preload and/or endplay, for example, spherical roller
bearings,
deep groove ball bearings, and the like. In the following discussion and
claims, bearing
16 may be referred to as the "outboard bearing" and bearing 18 may be referred
to as the
"inboard bearing."
[0040] As shown in FIGURE 3, as is typical of bearings, outboard bearing 16
includes
an inner race (or cone) 15, an outer race (or cup) 17, a plurality of rollers
22, and a roller
cage 24. Similarly, inboard bearing 18 includes an inner race (or cone) 19, an
outer race
(or cup) 21, a plurality of rollers 26, and roller cage 28. As shown in FIGURE
3, the
outer race 17 of outboard bearing 16 is positioned, for example, an
interference fit, into a
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annular cavity 29 having a annular retaining flange 30. Similarly, the outer
race 21 of
inboard bearing 18 is positioned into an annular cavity 31 having a retaining
flange 32.
Also, the inner race 15 of outboard bearing 16 is positioned, for example, a
sliding fit,
onto the outside diameter of spindle 14 and the inner race 19 of inboard
bearing 18 is
positioned against a shoulder 34 of spindle 14, which may be a sliding or
interference fit
to the spindle diameter. As such, any loads applied to hub 12 or spindle 14
are
transferred to inboard bearing 18.
[0041] According to some teachings in the art, outboard bearing 16 and inboard
bearing 18 can be provided with at least some preload to enhance the
performance or
bearing life and the performance or life of wheel hub assembly 10. For
example, as
described in the Timken Tech Tip, Volume 6, Issue 3 (copyrighted 2001)
entitled
"Preload in Wheel
Bearings"[http://wvvvv.timken.com/products/bearings/techtips/ PDFs /
Vol6No3.pdf#search ='Bearing%20Preloadi
Slight preload [on wheel bearings] can improve bearing, seal, and tire life,
but
only if the entire process is in control. "In control" means that you actually
know
the bearing setting process will result in a consistent bearing setting range.
The Tech Tip continues,
Unfortunately, neither dial indicators nor any other standard tool will tell a
technician the amount of preload in a wheel end....To date, there isn't
anything
available that will confirm that the bearing fastener is providing the correct
preload setting." [Emphasis added.]
In other words, one of the leading bearing suppliers in the world believes
that
conventional torquing methods and dial indicator methods have proven to be
unsatisfactory means of providing preload and endplay. Specifically, prior art
methods
have been shown to provide unreliable and non-repeatable preloads and/or end
play to
bearings such as bearings 16 and 18. Moreover, such experts in the field
contend that
"there isn't anything available" that can confirm a bearing preload. However,
the preload
assembly 20 according to aspects of the present invention provides such a
device - a
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reliable, accurate, and repeatable means of providing preload and/or endplay
adjustment
to bearings such as bearings 16 and 18. In addition, aspects of the invention
provide
means for monitoring the preload on the bearings to, for example, ensure that
the desired
preload is provided, in contrast to the unreliable and often inaccurate
assumed preloading
of the prior art.
[0042] As shown in FIGURES 1-3, preload assembly 20 includes a rod or shaft 40
mounted for rotation within a housing or frame 42, and a means 44 for
compressing
hub 12 against the outer race 21 of inboard bearing 18, in which the means 44
for
compressing is mounted to rod 40. Means 44, through housing 42 and hub 12,
provides a
known and predetermined preload to bearing 18. Housing 42 may be referred to
as "the
shoe" or "the foot" of preload assembly 20. Rod 40 is adapted to attach to the
exposed
end 13 of shaft 14, for example, by means of collar 46, though other
attachment means
may be used. Means 44 may be mounted to rod 40 by means of adjustment nut 48
which
may be threaded to rod 40 and provide a compressive load to means 44. Nut 48
may be
adapted to facilitate rotation of nut 48, for example, nut 48 may include arms
50 or a
hand wheel that can assist a mechanic while manually tightening or
untightening nut 48.
In one aspect, nut 48 may be adapted to be rotated by an automated tool, for
example, a
drill or stepper motor. For instance, nut 48 may be fashioned with a hex head
or threads
to engage an automated tool, for example, a torque motor. One such automated
tool is
disclosed in FIGURE 7, discussed below.
[0043] Means 44 may be any means that is adapted to transfer the compressive
load
provided by nut 48 to hub 12 and outer bearing race 21 of bearing 18. In one
aspect,
means 44 may simply comprise an extension of housing 42 whereby nut 48
contacts and
compresses housing 42 against hub 12, though, absent a means to monitor the
load
transmitted, such a system would not be as advantageous as other aspects of
the
invention. In another aspect of the invention, means 44 is not only adapted to
transfer a
load from but 48 to outer race 21, but means 44 also provides a means for
monitoring the
compressive load transferred, for example, some means of direct or indirect
indication of
the load transferred to outer race 21, that is, the preload on bearing 18.
CA 02576337 2007-01-25
[0044] In one aspect of the invention, the indication of the compressive load
transferred
through means 44 may be provided mechanically, for example, by means of
compression
springs having a known spring constant, for example, coil springs or disc
springs, and a
deflection indicator, for example, a dial indicator, as is known in the art.
In this aspect,
the dial indicator may be mounted to detect and indicate the compression of
one or more
springs positioned in means 44 due to the advancement of nut 48, and the
compression
load calculated from the deflection indicated and the known spring constant of
the
springs used. This aspect of the invention may provide a reliable and
repeatable means
for monitoring the preload provided to bearing 18.
[0045] In another aspect of the invention, means 44 may provide an indication
of the
compression load transferred by nut 48 electronically, for example, by means
of a load or
pressure sensor, for instance, one or more strain gages or load cells
positioned in
means 44. In this aspect of the invention, the load sensor may be wired to an
appropriate
processor and display to, for example, provide a digital readout of the
compressive load
to the mechanic operating preload device 20. The transmission of signals from
the sensor
may also be practiced wirelessly, for example, by means of an RF signal. This
aspect of
the invention may also provide a reliable and repeatable means for monitoring
the
preload provided to bearing 18.
[0046] In another aspect of the invention, means 44 may include at least one
fluid, for
example, a gas, such as air; or a liquid, such as, water, oil, or hydraulic
fluid, the pressure
of which can be detected and monitored, for example, by means of a pressure
gage,
pressure sensor, or a mechanical indicator. In one aspect, the fluid pressure
may
comprise the source of compressive load on bearing 18. One apparatus that may
be used
to effect this aspect of the invention is shown in FIGURE 7. The fluid may be
retained in
a cavity for example, a deformable cavity, such as a bladder or hose, for
example, an air
spring; or a cavity having rigid walls and at least one moveable wall, for
example, as in a
cylinder and piston. In one aspect, the deformable cavity or air spring may be
made of
molded rubber, somewhat like an inner tube, and the configuration of means 44
may be
adapted accept the molded rubber when inflated and deflated.
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[00471 When air is used as the fluid, the air may be provided by conventional
"shop
air" at a pressure of about 100 psig. The pressure of the fluid in the
deformable cavity
may be monitored by means of senor or pressure gage, for example, a pressure
gas
mounted to a nozzle inserted the wall of the deformable or non-deformable
cavity. In one
aspect, a mechanical indicator may be activated, for example, a lever
deflected when the
desired fluid pressure in means 44 is reached advising the mechanic. One
aspect of the
invention having a means 44 having a fluid is illustrated in FIGURES 1-3.
FIGURE 4 is
a detailed view of the means 44 for providing a preload shown in FIGURE 3 and
identified by detail 4.
[0048] In the aspect of the invention shown in FIGURE 4, means 44 comprises a
housing 52 and a movable piston 54 mounted for axial movement in housing 52.
In this
aspect of the invention, an internal cavity 56 is provided in housing 52
between the
between housing 52 and piston 54, for example, an annular cavity. Internal
cavity 56 is
at least partially filled, for example, substantially completely filled, with
a fluid, for
example, a gas, air, oil, water, and the like, that produces a hydrostatic
pressure, P, when
housing 52 is compressed by the advancement of nut 48 on rod 40. Piston 54 may
be
provided with one or more seals 61 and 63, for example, one or more wiper
seals, to
minimize or prevent the leakage of fluid from cavity 56. Also, housing 42 may
include
an internal cavity 57, which provides clearance for the displacement of piston
54 within
housing 52. In one aspect, a leakage path through housing 52 may be provided
from
cavity 57 to minimize or prevent buildup of fluid in cavity 57 which may
interfere with
the proper operation of piston 54. Piston 54 may also be retained in housing
52 by means
of a retainer or snap ring 55. Housing 52 and piston 54 may be fabricated by
machining
from solid bar or plate stock, welded from bar or plate, forged, or cast.
[0049] As shown in FIGURE 4, the compressive load applied by the advancement
of
nut 48 is transmitted to housing 52, to the fluid in cavity 56, to piston 54,
to cylindrical
housing 42, to hub 12, and ultimately to the outer race 21 of bearing 18.
Thus, according
to aspects of the invention, the hydrostatic pressure induced in the fluid in
the cavity 56
by the advancement of nut 48 provides a direct indication of the preload on
bearing 18.
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[0050] In one aspect, the pressure P in cavity 56 may be monitored, for
example,
continuously, by means of a pressure sensor or pressure gage. As shown in
FIGURE 4,
pressure P in cavity 56 may be monitored by one or more pressure indicators 60
which is
adapted to detect the pressure P in cavity 56 via a passage 58 in housing 52.
Pressure
indicator 60 may be an analog or digital pressure gage. Pressure indicator 60
may be a
pressure sensor adapted to detect the pressure P in cavity 56 and forward an
electrical
signal corresponding to the pressure P to a processor or controller adapted to
display the
pressure, record the pressure, energize a circuit in response to the pressure,
and/or
provide a signal to the mechanic, for example, a tone or bell that a pressure
corresponding to a desired preload on bearing 18 has been achieved.
[0051] According to aspects of the invention, the pressure P and the
corresponding
geometry (for example, the inside and outside diameters of cavity 56) may be
used by a
mechanic to determine the preload on bearing 18. For example, for a desired
preload L
(in pounds, Newtons) and a given area of piston 54 exposed to pressure P (in
square
inches, square meters), the desired pressure of the fluid in cavity 56 may be
determined
by the equation P = L/A, for example, in psi or Pascal. For example, when a
preload of
6000 pounds lbs. (L) is desired to provide an compressive deflection of 0.003
inches on
bearing 18, and the outside diameter of annular cavity 56 is 3 inches and the
inside
diameter of cavity 56 is 1 inch, the target pressure, P, is calculated by
P = L/A = (6000 lbs)/((7t/4)(32 ¨ 12)) = 6000 lbs/(27c in2) = 955 psig.
Equation 1
This pressure may now be used as the target pressure in cavity 56 and detected
by
pressure indicator 60 to provide the desired 0.003-inch compressive deflection
for
bearing 18. According to aspects of the present invention, the pressure of the
fluid in
cavity 56 may be monitored to determine when the desired pressure P is
achieved
wherein the desired preload is provided to bearing 18.
[0052] In one aspect of the invention, one or more antifriction bearings may
be
provided for means 44. For example, in one aspect, one antifriction bearing 62
may be
positioned between nut 48 and housing 52 and another antifriction bearing 64
may be
located between piston 54 and housing 42. Bearings 62 and 64 may be roller-
type
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CA 02576337 2007-01-25
bearings or reduced friction material bearings. For example, bearings 62 and
64 may
comprise needle bearings or a material containing at least some PTFE, for
example,
DuPont's Teflon() PTFE or Saint-Gobain's RulonCD PTFE, or their equivalent.
Bearings 62 and 64 may be retained by one or more retaining devices 65 and 66,
for
example, one or more snap rings.
[0053] As shown in FIGURES 1-4, housing or frame 42 is adapted to transmit the
compressive load provided by the advancement of nut 48 to hub 12. In one
aspect,
housing 42 may be any structure adapted to transmit this load while not
interfering with
the movement and operation of nut 11 and collar 46. In one aspect, housing or
frame 42
comprises a cylindrical housing and may include at least one opening to permit
access to
nut 11 and collar 46, for example, for servicing by a mechanic. In the aspect
of the
invention shown in FIGURES 1-4, housing 42 comprises an upper flange 70
adapted to
receive the force transmitted by means 44, a lower plate or ring 72 adapted to
transmit a
load to hub 12, and a plurality of posts 74 spaced about flange 70 and ring 72
to transmit
a load between flange 70 and ring 72. In one aspect, flange 70 may be any
plate adapted
to engage piston 54 and posts 74. Ring 72 may be any annular plate adapted to
receive a
load from posts 74. In one aspect, the interface between ring 72 and hub 12
may be
provided with an antifriction bearing, for example, a needle bearing or a PTFE-
containing
material, as described above with respect to bearings 62 and 64. Posts 74 may
comprise
cylindrical posts, for example, circular cylindrical or rectangular
cylindrical, extending
from flange 70 to ring 72. When housing 42 is provided as a cylindrical body,
posts 74
may comprise sections of the cylindrical body remaining when openings are
introduced
to the cylindrical body. In one aspect, ring 72 may be omitted wherein posts
74 contact
the surface of hub 12 directly. When ring 72 is omitted, posts 74 may be
provided with
means to reduce friction between the ends of post 74 and hub 12. For example,
the ends
of posts 74 may be adapted to provide antifriction bearings or rollers or
reduced friction
materials, such as, a PTFE-containing material. Housing 42 may be machined
from stock
shapes, assembled by means of fasteners, fabricated by welding, forging,
casting, or a
combination thereof
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CA 02576337 2007-01-25
[0054] In one aspect of the invention, housing or frame 42 may be adapted to
contact
the inner race of outboard bearing 16, that is, instead of contacting hub 12,
and transmit a
preload to bearing 18. For example, with reference to FIGURE 3, in some wheel
hub
assemblies 10, the diameter of retaining nut 11 may be smaller than the
diameter of inner
race 15 of outboard bearing 16 whereby access to inner race 15 is not
obstructed by
nut 11. (In FIGURE 3, the diameter of nut 11 is greater than the diameter of
inner
race 15 and thus inner race 15 cannot be directly accessed.) Under this
condition,
housing 42 may be sized or adapted to contact the inner race 15 whereby the
compression
load providing by advancing nut 48 may be transmitted to outboard bearing 16
via inner
race 15 and from bearing 16 to hub 12 and to outer race 21 of inboard bearing
18. That
is, according to one aspect of the invention, a preload may be transferred to
inboard
bearing 18 by means of compression on the face of hub 12 or on the inner race
15 of
bearing 16. In one aspect, compressive deflection is imposed on both of
bearings 16
and 18.
[0055] According to aspects of the invention, the compressive load transmitted
to the
bearing 18 is transmitted through hub 12. Therefore, at least some of the
compressive
deflection provided by the present invention will comprise deflection of hub
12.
Therefore, in some aspects of the present invention, when determining the
compressive
deflection of bearing 18 under preload, the deflection of hub 12 may also be
considered.
For example, a dial indicator mounted on, for example, housing 42 to detect
the
compression deflection of bearing 18 may also detect the deflection of hub 12,
depending upon the magnitude of the load and the stiffness of hub 12. In one
aspect of
the invention, when deflection of hub 12 may effect the compressive
deflection, the
deflection measured can be normalized to or compensated for the hub stiffness,
that is,
hubs of varying stiffness may have varying deflections though the
corresponding
compressive deflection of bearing 18 will be substantially the same. However,
any
deflection of hub 12 will likely have little effect upon the compressive force
transmitted
to bearing 18.
[0056] It will be apparent to those of skill in the art that the design of
housing 42 may
be modified whereby housing 42 may contact inner race 15. For example, flange
70 and
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CA 02576337 2007-01-25
ring 72 may be reduced in diameter whereby ring 72 may contact inner race 15.
This
alternative aspect of the invention is shown FIGURE 5. FIGURE 5 illustrates a
partial
cross sectional view of an alternate design of housing 42 for transferring the
compressive
load from means 44 to bearing 18 via inner race 15 of outboard bearing 16. In
this
aspect, the size of nut 111 on spindle 14 is smaller than nut 11 shown
earlier, whereby an
inner race 15 is exposed and can be contacted by a modified housing 142. Inner
race 15,
bearing 16, and hub 12 are shown in FIGURE 5 for reference. In this aspect of
the
invention, the diameter of upper flange 70 is reduced to the diameter of upper
flange 170
shown in FIGURE 5, the diameter of ring 72 is reduced to the diameter of ring
172
shown in FIGURE 5, and posts 74 are replaced with posts 174. As a result, the
compressive load can be transferred to inner race 15 of bearing 16. In another
alternative
design of housing 42, posts 74 may be angled or tapered inward toward the
centerline of
the assembly and the diameter of ring 72 reduced accordingly whereby ring 72
may
contact inner race 15. Other modifications to housing 42 to achieve this
contact with
inner race 15 will be apparent to those of skill in the art.
100571 As discussed previously, rod 40 is adapted to attach to the exposed end
13 of
spindle 14. Though this may be effected by many conventional means, including
welding and mechanical fasteners, in the aspect of the invention shown in
FIGURES 1-4,
rod 40 is attached to end 13 of spindle 14 by means of a collar 46. In the
aspect shown,
collar 46 is mounted to rod 40 by means of internal threads 47 in collar 46
that thread
onto external threads 49 on rod 40. Collar 46 also includes a second set of
internal
threads 45 that engage external threads 51 on spindle 14. In one aspect, only
2 or 3
external threads 51 need be engaged by collar 46. According to one aspect,
multiple
collars 46 having varying diameters may be provided to accommodate varying
diameters
of spindle 14. Each of these collars 46 may be adapted to engage external
threads 49 on
rod 40. In one aspect, the movement of rod 40 may be limited by a collar or
ring 76, for
example, a snap ring, mounted on rod 40.
[0058] Rod 40, housing 42, collar 46, nut 48, arms 50, housing 52, piston 54,
and
housing 42 may be fabricated from any conventional structural metal, for
example, iron,
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CA 02576337 2007-01-25
steel, stainless steel, aluminum, titanium, nickel, magnesium, brass, or
bronze, among
others.
[0059] In one aspect of the invention, apparatus 20 may be used to apply and
monitor a
preload to inboard bearing 18. In a typical procedure, the wheel (not shown)
mounted to
hub assembly 10, for example, mounted to studs on hub 10, as exemplified by
stud 100 in
FIGURE 3. As shown in FIGURE 4, apparatus 20 may be prepared by assembly and
filling cavity 56 with a fluid, for example, oil, through one of the access
ports 58 that is
not occupied by pressure indicator 60. Nut 11 may be loosened or hand
tightened prior to
mounting apparatus 20, though any light load on nut 11 will typically be
relieved with
application of tension to spindle 14 by means of rod 40. Apparatus 20 is then
mounted to
hub assembly 10 by attaching rod 40 to spindle 14 by means of collar 46. As a
result,
housing 42 is brought into contact with hub 12. Assuming a desired compressive
deflection for bearing 18, for example, 0.003 inches, and a corresponding
preload, L, the
desired target pressure in cavity 56 can be calculated by Equation 1.
[0060] The loading of bearing 18 is initiated by advancing, that, is
tightening, nut 48,
against housing 52 via bearing 62, for example, by means of arms 50. The build
up of
pressure in cavity 56 as indicated by pressure indicator 60 may be monitored
by the
mechanic. The tightening of nut 48 continues until the target pressure is
achieved. The
hub assembly may be rotated at least once to provide proper seating of the
rollers in
bearing 18. Once the target pressure is achieved in cavity 56, and the desire
preload is
applied to bearing 18, nut 11 may be tightened against inner race 15 to
maintain the
preload after apparatus 20 is removed. The desired tightening of nut 11 may be
determined by monitoring the pressure in cavity 56 on pressure indicator 60.
For
example, should the pressure begin to decrease during tightening of nut 11,
the nut may
be tightened too much. The reduction in pressure means that the preload on
bearing 18 is
being relieved and transferred to nut 11 by the tightening of nut 11. In one
aspect of the
invention the tightening of nut 11 can proceed until a decrease in pressure is
observed.
At that point, the tightening of nut 11 may be stopped, or nut 11 may be
untightened
slightly, for example, about 1/8 turn. Again, the hub assembly may be rotated
at least
once to provide proper seating of the rollers in bearings 16 and 18. Upon
completion of
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CA 02576337 2007-01-25
the preloading, apparatus 20 may be removed from wheel hub assembly 10 and,
for
example, the wheel remounted. Variations on this procedure while not deviating
from
the desired results may be apparent to those of skill in the art.
100611 In another aspect of the invention, apparatus 20 may be used to adjust
the
endplay of a bearing. For example, in some bearing installations it is
desirable to create
an endplay for a bearing assembly, for example, an endplay of between about
0.001
inches and about 0.003 inches. For instance, see undated instructions entitled
"ProTorq0
Advanced Axle Spindle Nuts" flyer by Stemco, of Longview, Texas. Although
procedures such as these which apply specified torques to the nut are intended
to provide
the specified endplay in the bearing, the inventor has found that the actual
endplay
provided by such procedures may vary dramatically. For example, the actual
axial
deflection of the bearings that results from the applied torque may vary due
to, among
other things, differences in torque resistance (or friction) between mating
surface, for
example, between nut 11 and the axle threads 15 and between the face of nut 11
and the
surface of bearing 16, among others. Further errors may be introduced by such
torque-
based procedures by misalignment of the bearing rollers that may occur in
between steps
in the specified procedures. Therefore, there is a need in the art to provide
an accurate
and repeatable means of providing bearing endplay. One aspect of the invention
addresses this need.
[0062] Aspects
of the present invention eliminate the inaccuracies that are inherent in
prior art endplay adjustment procedures and can be used to provide accurate
end play
settings of as fine as 0.001 inches and 0.002 inches. With reference to the
cross section
shown in FIGURE 3, one method of providing accurate endplay adjustment
includes the
following steps. Starting with a greased and assembled wheel end assembly 10
(this
procedure may be practiced with or without the wheels present), nut 11 is
unloosened or
installed and only fastened hand tight. The apparatus 20 shown in FIGURE 1-4
is then
mounted to the wheel hub assembly 10. Specifically, rod 40 having means 44,
which
comprises a fluid-containing housing 52, is attached to axle 14 by means of
collar 46, and
housing 42 is mounted to hub 12. In this aspect of the invention, the fluid in
housing 52
is assumed to be hydraulic fluid. According to this procedure, nut 48 is
rotated and
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CA 02576337 2013-10-02
advanced, for example, by means of arms 50 to produce a target hydraulic fluid
pressure
of, for example, 1000 psig, in cavity 56 as indicated by pressure indicator
60, for
example, an analog pressure gage. The target pressure is typically
predetermined by
Equation 1 and the desired compressive deflection or endplay desired in
bearing 18. The
target pressure will vary depending upon the size and type of bearings used
and the size
of cavity 56, among other things.
100631 The wheel hub assembly 10 is then rotated about spindle 14 at least one
complete revolution, typically, at least three complete revolutions, to seat
the rollers in
inboard bearing 18. (See Timken Tech Tip Volume 1, Number 6 entitled "Why
oscillate
or rotate a bearing"
http:://www.Timken.com/products/bearings/techtips/tip6.asp). The
pressure indicated by the pressure indicator 60 (that is, about 1000 psig) may
vary as
rollers 26 of inboard bearing 18 are seated by the rotation. If the pressure
in cavity 56
deviates from the desired target pressure, the pressure in cavity 56 may be re-
established
by rotating nut 48, for example, by means of arms 50. The rotation of wheel
assembly 10
about spindle 14 and the repressurization step may be repeated until rollers
26 of inboard
bearing 18 are properly seated and the pressure indicted by pressure indicator
60
stabilizes to about the target pressure. It is understood that there may be
slight variation
in the pressure in cavity 56 due to slight misalignments (that is, the out of
"squareness")
of the installed bearing, among other things. The rollers 26 of inboard
bearing 18 are
then substantially seated in inner race 19.
[0064] Next, with the inboard bearing 18 properly seated by the above
procedure, the
endplay in outboard bearing 16 may be adjusted. While the target pressure
(again, for
example, about 1000 psig) is maintained in housing 52, nut 11 is rotated and
tightened,
for example, with a hand held wrench, on spindle 14, for example, slowly.
During or
after the tightening of nut 11, wheel assembly 10 is rotated about spindle 14
whereby
rollers 22 of outboard bearing 16 are seated in inner race 15. The nut 11 is
continued to
be tightened until the pressure indicted by pressure indicator 60 just begins
to drop. This
drop in pressure indicates that the preload on inboard bearing 18 is being
relieved by the
compression of nut 11 against inner race 15 of outboard bearing 16. Nut 11 is
then
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CA 02576337 2007-01-25
,
loosened slightly to so that the target pressure is regained, and thus the
preload on
inboard bearing 18 is reestablished, that is, typically, without retightening
nut 48. This
condition of adjustment, where the desired preload is established in the
inboard
bearing 18 and the compression of nut 11 on inner race 15 is such that any
further
tightening will unload the preload on inboard bearing 18, according to one
aspect of the
invention, is referred to as "the load reference point." Practicing aspects of
the present
invention, this load reference point can be fairly easily identified by feel
by a mechanic.
According to the invention, at this load reference point, the rollers in both
outboard
bearing 16 and inboard bearing 18 are properly seated and desired preload
(that is, due to
the 1000 psig pressure in housing 52) is applied to outer race 21 of inboard
bearing 18.
[0065] According to aspects of the invention, a method and an apparatus are
provided
by which the mechanic can accurately determine the load reference point for a
bearing
assembly. Aspects of the present invention are not prone to the variability of
the preload
due to the unknown and unpredictable frictional forces between mating
surfaces,
regardless of what the desired bearing preload and/or endplay setting.
According to
aspects of the invention, after establishing the neutral point position, the
mechanic may
relatively easily provide the desired adjustment of nut 11 that accurately
achieves the
desired bearing preload and/or endplay setting.
[0066] As is known in the art, a known preload, for example, the 6000 pounds
in the
example above, results in a known value of axial compression of a bearing, for
example,
an axial compression of 0.004 inches. According to aspects of the invention,
in the load
reference point position, where both bearings are correctly aligned and at
zero preload on
nut 11, the preload on inboard bearing 18 will be captured by or transferred
to nut 11 if
nut 11 is loosened, for example, precisely 0.004" from the load reference
point.
Therefore, according to aspects of the invention, the preload may be varied or
the endplay
provided by precisely controlling the rotation of nut 11. One aspect of the
present
invention provides a method and apparatus for controlling the rotation of nut
11 to
provide a desired preload or endplay.
-21-
CA 02576337 2007-01-25
[0067] According to one aspect of the invention, a method and a apparatus is
provided
of employing a calibrated wrench that can be used to accurately control the
rotation of
nut 11 to provide a desired preload or endplay. This method and apparatus are
illustrated
in FIGURES 6A, 6B, and 6C. FIGURES 6A, 6B, and 6C are partial axial elevation
views of the apparatus 20 as viewed along the section lines 6-6 shown in
FIGURE 4 with
the addition of a wrench 90. For ease of illustration, FIGURES 6A, 63, and 6C
only
illustrate the portion of housing or frame 42, specifically ring 72 and posts
74. These
figures also illustrate the end of shaft 14 and nut 11 mounted on shaft 14.
[0068] According to one aspect of invention, wrench 90 includes a handle 89
and two
opposing tines 92 spaced to engage the opposite flats on nut 11. Wrench 90
also includes
at least one recess 94 positioned between tines 92. Recess 94 includes two
opposing end
surfaces 91, 93 adapted to contact a post 74 and function as stops to the
movement of
wrench 90. In one aspect, stops 91, 93 may be provided by one or more
projections or
bosses between tines 92 instead of one or more recesses 94. In another aspect,
the
stopping surfaces may be provided by the closed ends of one or more slots 95
(shown in
phantom) in ring 72 that are adapted to receive one or more pins 97 (also
shown in
phantom) projecting from beneath wrench 90. The one or more slots 95 may vary
in
length to correspond to one or more angular rotations. Other adaptations of
wrench 90
and/or ring 72 and posts 74 may be provided to provide the desired limitations
in the
rotation of nut 11. Wrench 90 may have a thickness ranging from about 0.50
inches to
about 1 inch or more.
[0069] As shown in FIGURE 6A, recess 94 may have a common centerline with
handle 89; however, recess 94 may be located anywhere between tines 92. In one
aspect,
a plurality of recesses 94, for example, 3 or more recesses 94, may be
provided in
wrench 90. According to one aspect of the invention, the arc length separating
the
opposing ends 91, 93 of recess 94 is provided to limit the rotation of wrench
90 when
wrench 90 is used to rotate nut 11 to provide the desired preload or end play.
This aspect
of the invention is more clearly illustrated by describing one procedure that
may be used
as shown in the sequence of steps illustrated by FIGURES 6A, 6B, and, 6C.
-22-
CA 02576337 2007-01-25
[0070] In this example, the size of the recess 94 in handle 90, that is, the
arc length
between the ends 91, 93 of recess 94, is provided whereby the rotation of
wrench 90
provides a predetermined angular displacement, a. (As will be discussed below,
this
angular displacement, a, may be determined from the desired preload or endplay
and the
pitch of the threads on spindle 14.) As shown in FIGURE 6A, wrench 90 may be
mounted to nut 11 whereby tines 92 engage opposing flats of nut 11 and recess
94
accepts one of the posts 74 of housing 42. As shown in FIGURE 613, the engaged
wrench 90 and nut 11 are held fixed by holding handle 89 and hub 12 is
carefully rotated
in a clockwise direction as indicated by arrow 96 until one end 91 of recess
94 contacts a
post 74. This contacting of end 91 of recess 94 upon post 74 establishes the
base position
for this angular adjustment of nut 11.
[0071] Now, as shown in FIGURE 6C, hub 12 is fixed from further rotation,
wrench 90
is rotated in a counter-clockwise direction - as indicated by arrow 98 -
whereby the
opposite end 93 of recess 94 contacts post 74, and thus the rotation of nut 11
is limited to
the arcuate spacing between the ends 91, 93 of recess 94. Since the wheel hub
12 is
typically substantially more massive than wrench 90 and nut 11, hub 12 may
simply be
retained by hand, or other means, while rotating wrench 90 and nut 111.
However, due to
the relative inertia of hub 12, it may not be necessary for the mechanic to
restrain hub 12
while rotating wrench 90 and nut 11, while ensuring that rotation of the
wrench is
stopped when end 93 contacts post 74.
[0072] It will
be apparent to those of skill in the art that the desired angular rotation a
of nut 11 is not the arcuate length between ends 91 and 93 of recess 94, but,
due to the
diameter of posts 74, the desired angular rotation a corresponds to the
arcuate length
between the center of posts 74 before and after rotation.
[0073] One example of the use of the method and apparatus described with
respect to
FIGURES 6A, 6B, and 6C, is illustrated by the following example. This example
assumes that the wheel hub assembly 10 has been adjusted whereby a compression
of
bearing 18 has been established of, for example, 0.004 inches, and bearings 16
and 18 are
in their "load reference point." It is also assumed that the desired endplay
of bearing
-23-
CA 02576337 2007-01-25
supports 16 and 18 is 0.001 inches and the threads on nut 11 and shaft 14 have
a pitch of
12 threads per inch (that is, 1/12 inches per revolution), which is a common
pitch for
truck axles. The total required displacement of nut 11 to overcome the preload
compression and obtain the desired endplay is 0.004 + 0.001 = 0.005 inches.
For a 12
pitch thread, the required rotation of nut 11 is (0.005 inches)/(1/12
inches/revolution) =
0.060 revolutions of nut 11 to provide the desired endplay, which corresponds
to (0.060
revolutions) x (360 degrees/revolution) = 21.6 degrees. For a typical spindle
thread pitch
of 12 threads per inch, an accuracy of 0.001 inches relates to more that four
degrees of
rotation of nut 11 or wrench 90, and that relates to an excursion of more than
an eighth of
an inch at the radial distance where post 74 is located. Therefore, by
fabricating the
recess 94 of handle 90 whereby angle a is, for example, 21.6 degrees, wrench
90 can be
used in the procedure described above to provide the 0.001 inches of endplay
desired in
this example. Other examples of the use of wrench 90 will be apparent to those
of skill in
the art.
[00741 FIGURE 7 illustrates a right elevation view, partially in cross
section, of
another arrangement 110 according to another aspect of the invention. In this
aspect,
fluid pressure in means 44 may provide the compressive load to bearing 18. In
this
aspect, of the invention, instead of the compressive force provided by the
advancing of a
nut, such as nut 48 in FIGURE 3, the compressive force provided by nut 48 may
be
supplemented by or replaced by the fluid pressure force provided to means 44,
for
example, the fluid pressure provided to cavity 56 in housing 52 having piston
54. In this
aspect, the fluid pressure may be provided by conduit or hose 200. Hose 200
may supply
fluid, for example, hydraulic fluid, from a pressurized supply, for example, a
pump. The
fluid supplied to hose 200 may vary from 500 to 3000 psig. In one aspect, the
fluid
pressure provided through hose 200 may be the only supply of compressive force
to
bearing. In this aspect shown in FIGURE 7, rod 40, shown in FIGURE 3, is
replaced by
rod 140. Similar to rod 40, rod 140 engages spindle 14 as described in other
aspects of
the invention. However, contrary to rod 40, rod 140 includes a knob 145 that
restrains
means 44, for example, through an antifriction bearing. Knob 145 may be
knurled or
include a hand wheel or one or more arms 50 similar to nut 48.
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CA 02576337 2007-01-25
[0075] The aspect of the invention shown in FIGURE 7 may be used to
automatically
regulate the compressive load on bearing 18, for example, by regulating the
pressure
introduced to means 44 through hose 200. In one aspect, the invention may
include an
automatic controller, for example, a PID controller, personal computer, or PLC
controller
adapted to regulate the pressure in hose 200. For example, the predetermined
preload or
endplay and the parameters of the bearing being loaded may be entered into the
controller
and, after mounting rod 140, housing 42 and means 44 to hub 12, the controller
may
automatically ramp up the fluid pressure to provide the desired preload or to
verify an
existing preload. The aspect of the invention shown in FIGURE 7 may be
suitable for
production line applications, among others.
[0076] In one aspect, the fluid provided by hose 200 may be provided by
pressure
increasing device, for example, a pressure intensifier, that is, a device that
converts one
pressure to a higher pressure. For example, the pressure-increasing device may
be
provided with a pressure supply of, for example, 100 psig (for instance, shop
air) and
increased to, for example, 2000 psig hydraulic fluid, which is then supplied
to hose 200.
Other sources of high-pressure fluid may be provided according to aspects of
the
invention.
[0077] It will also be understood that due to the variations in angle a that
may be
desired, for different bearings, different spindle pitches, and different
endplays and
preloads, among other things, many different wrenches 90 having recesses 94 of
varying
width may be provided. In one aspect of the invention, a plurality of recesses
94 of
varying width or angle a may be provided in handle 90. In another aspect of
the
invention, recess 94 in handle 90 may be adjustable by the operator, for
example, the
position of at least one end of recess 94 may be variable to provide for
varying angles a.
In another aspect, the width between tines 92 if wrench 90 may be variable to
permit use
of wrench 90 on nuts 11 of varying diameter. According to aspects of the
invention, an
adjustable wrench may be provided that can be calibrated for a desired preload
and/or
endplay values for a specific spindle and hub design.
-25-
CA 02576337 2007-01-25
[00781 Aspects of the invention may also be used to evaluate the preload or
endplay on
an existing bearing or bearing assembly. For example, an existing truck hub
assembly
may be evaluated for its existing preload and compared to the desired preload,
and, if
necessary, adjusted accordingly. First, the truck may be jacked up, if needed.
(The hub
may be allowed to cool, if necessary). Apparatus 20 may then be mounted to hub
12 and
spindle 14 (with reference to FIGURE 4) and the means 44 actuated to introduce
tension
to spindle 14 and compression to hub 12. (The wheel may be mounted to
removed.) The
means 44 may be regulated to, for example, vary the fluid pressure, to
gradually increase
the preload on bearing 18. While the load is increased, a mechanic can
repeatedly check
the load on or the "tightness" of nut 11. When nut 11 begins to loosen, the
existing
preload on bearing 18 has been met or exceeded. A comparison of the actual
preload
indicated by means 44, for example, the fluid pressure, with the desired
preload can then
be made. Any adjustments to the preload, either higher or lower, can be made
according
to the procedures described above.
[0079] While one aspect of the present invention, in which the inboard bearing
18 is
loaded through hub 12, can provide a useful indication of the preload present
in bearings
16 and 18, for example, by assuming a predetermined distribution of load
between
bearing 16 and 18 and distributing the preload measured on bearing 18
accordingly, other
aspects of the invention can provide an more accurate indication of the
preload on
bearings 16 and 18. For example, the aspect of the invention illustrated and
described
with respect to FIGURE 5 above and the aspect of the invention illustrated and
described
with respect to FIGURES 8 through 19 below, in which the loading of bearings
16 and 18
transmitted via bearing 16.
[0080] FIGURE 8 is perspective view of a wheel hub assembly 201 having a
bearing
preloading assembly 202 according to another aspect of the invention. As will
be
discussed more fully below, in contrast to the apparatus discussed above with
respect to
FIGURES 1-5, preloading assembly 202 introduces a load to the outboard bearing
16,
instead of to hub 12. According to this aspect of the invention, contact with
the inner
race of the outboard bearing is accomplished by means of specially designed
axle nut or
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CA 02576337 2007-01-25
an axle nut arrangement. Unlike prior art methods and devices, aspects of the
invention
permit mechanics to apply or confirm a preload to outboard bearing 16.
[0081] FIGURE 9 is a right side elevation view of the hub assembly 201 shown
in
FIGURE 8 and FIGURE 10 is a right side elevation view, partially in cross
section, of the
assembly shown in FIGURE 8. FIGURE 11 is a detailed view of the means for
providing
a preload shown in FIGURE 10 and identified by detail 11. FIGURES 8-11 are
views
similar to those shown in FIGURES 1-3 and include many of the structures shown
in
FIGURES 1-3, which are identified with the same reference numbers that appear
in
FIGURES 1-3. These structures may typically comprise the same structures
having the
same properties as those discussed above with respect to FIGURES 1-5. For
example,
hub assembly 201 in FIGURES 8-11 includes a hub 12, a threaded shaft, axle, or
"spindle" 14, an outboard antifriction bearing 16, an inboard antifriction
bearing 18. As
shown in FIGURE 10, outboard bearing 16 includes an inner race (or cone) 15
and an
outer race (or cup) 17, and inboard bearing 18 includes an inner race (or
cone) 19 and an
outer race (or cup) 21.
[0082] As also shown in FIGURES 8-11, wheel hub assembly 201 includes preload
assembly 202 that, similar to preload assembly 20 shown in FIGURES 1-5,
includes a rod
or shaft 40 mounted to spindle 14 by means of collar 46, and a means 244 for
providing a
compressive load to bearing 16. Again similar to the aspects shown in FIGURES
1-5,
means 244 of preload assembly 202 shown in FIGURES 8-11 includes a nut 48
threaded
to shaft 40. Nut 48 may include arms 50 or a hand wheel to assist the operator
in rotating
nut 48. Means 244 of preload assembly 202, similar to means 44 discussed above
with
respect to FIGURES 1-5, may provide a compressive load to bearing 16 or means
44 may
be any means that is adapted to transfer the compressive load provided by nut
248 to the
inner race 15 of bearing 16. In one aspect, means 244 provides a means for
monitoring
the compressive load transferred, for example, some form of direct or indirect
indication
of the load transferred to inner race 15, as described above with respect to
means 44, for
example, by means of compression springs, electronically, or by means of a
fluid
pressure sensor, such as pressure gage 60.
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CA 02576337 2007-01-25
[0083] According the aspect of the invention shown in FIGURES 8-11, the
compressive load of nut 48 and/or means 244 is transmitted to bearing 16, and
to bearing
18, by means of loading adapter 210. In one aspect, loading adapter 210 works
in
conjunction with modified axle nut 220 to provide a load to inner race 15 of
outboard
bearing 16. As described above, for example, with respect to FIGURES 4 and 5,
conventional axle nuts, for example, axle nut 11 in FIGURE 5, are typically
larger in
diameter than inner race 15 of bearing 16 whereby no direct physical contact
can be made
with race 15 to, for example, apply a load. Under some conditions, for
example, as
shown in FIGURE 5, axle nut 11 may be smaller in diameter than inner race 15
where
inner race 15 may be directly contacted, for example, by housing 142, to
provide a load.
In the aspect of the invention shown in FIGURES 8-11, a specially designed
axle nut 220
having a recess that exposes the surface of inner race 15 and permits contact
by for
example, loading adapter 210. According to aspects of the invention, loading
adapter 210
transmits the compressive load from nut 48 and/or means 244 to inner race 15
of bearing
16, and thus to bearing 18. In one aspect, where race 15 is exposed, load
adapter 210
may be used with a conventional axle nut, for example, axle nut 11 in FIGURE
3.
However, when inner race 15 would be concealed by a conventional axle nut,
modified
axel nut 220 may be used according to aspects of the invention.
[0084] In contrast to other aspects of the invention, for example, those
illustrated in
FIGURE 4 and 5, the aspect of the invention shown in FIGURES 8-11 may provide
a
more accurate and reproducible indication of an existing or desired preload on
bearings
16 and 18. For example, since the load applied, for example, via means 244, is
directed
to bearing 16 and from bearing 16 to bearing 18, the load monitored and
indicated by
means 244 is thus a more accurate indicator of the combined preload on
bearings 16 and
18, for instance, no load bearing relationship need be assumed regarding the
relative
preloads on bearing 16 and 18.
[0085] FIGURE 12 is perspective view of the bearing loading adapter 210
shown in
FIGURE 11. FIGURE 13 is a side elevation view of the bearing loading adapter
210
shown in FIGURE 12 and FIGURE 14 is top plan view of bearing loading adapter
210
shown in FIGURE 12. As shown, adapter 210 includes a plate 211 and at least
two
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CA 02576337 2007-01-25
extensions, fingers, or arms 212, 213 from plate 211. In this aspect of the
invention,
extensions 212 and 213 are adapted to transmit the load applied to plate 211,
for example,
by the compression of nut 48, to the bearing 16. As shown in FIGURES 12-13,
plate 211
typically includes a through hole or bore 214 that is adapted to receive rod
40, as shown
in FIGURE 11. Plate 211 may also include a raised boss 215 adapted to contact
means 244 for example, adapted to contact piston 54 or bearing 64 (see FIGURE
4). In
one aspect, extensions 212 and 213 may be moveable or deflectable to
facilitate assembly
of adapter 210 into engagement with bearing 16. For example, extensions 212
and 213
may include any interface with plate 211 or modification to extensions 212 and
213 that
permits extensions 212 and 213 to deflect to avoid interference with nut 11 or
nut 220.
As shown in FIGURES 12-14, in one aspect, extensions 212 and 213 may be
pivotally
mounted to plate 211. Plate 211 may include a pair of lugs or projections 216
having
through holes 217 and extensions 212, 213 may include recesses 218 adapted to
receive
projections 216 and extensions 212, 213 may include through holes 219. Pins
222 may
be provided in holes 219 in extensions 212, 213 that engage holes 217 in
projections 216
whereby extensions 212, 213 may rotate about pins 222 as indicated by double
arrows 224 in FIGURE 13.
[0086] Arms or extensions 212, 213 may include projections 225, 226,
respectively, for
example, arcuate projections adapted to engage the arcuate shape of inner race
15 of
bearing 16. Arcuate projections 225, 226 may be radiused to provide the same
curvature
of inner race 15, for example, a radius of between about 1 'A inches and about
3 inches.
Projections 225, 226 may include shoulders 227, 228, respectively, to assist
in engaging
race 15. In one aspect, since pins 222 (which transmit the load from plate 211
to
extensions 212, 213) may be located at a greater radial distance from the
center of shaft
14 than the radial distance to the point of contact on inner race 15 (see
FIGURE 11),
shoulders 227, 228 may be provided to minimize or prevent contact of
projections 225,
226 with nut 220. This aspect of the invention may ensure that the compressive
load
applied by means 244 is transmitted to race 15 and not borne by nut 220.
Minimizing or
preventing contact between extensions 212, 213 and nut 220 also permits nut
220 to be
freely rotated without contact with extensions 212, 213.
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CA 02576337 2007-01-25
[0087] Although only two extensions 212, 213 are illustrated in FIGURES 12-14,
according to one aspect of the invention, two or more extensions 212, 213 may
be
mounted to plate 211. For example, three or more extension 212, 213 may be
provided,
for example, uniformly spaced about plate 211. In one aspect, plate 211 may be
a
circular plate having two or more extensions 212, 213. In one aspect of the
invention,
extensions 212, 213 may include spring-loaded mountings to plate 211 whereby
extensions 212, 213 are biased into a position of engagement with race 215.
Adapter 210
and its components may be fabricated from any conventional structural metal,
for
example, iron, steel, stainless steel, aluminum, titanium, nickel, magnesium,
brass, or
bronze, among others.
[0088] FIGURE 15 is a perspective view of an axle nut 220 according to another
aspect
of the invention. FIGURE 16 is a side elevation view, partially in cross
section, of axle
nut 220 shown in FIGURE 15. As shown in FIGURES 15 and 16, nut 220 includes a
cylindrical body 240 having a first end 241 and a second end 242 and a
longitudinal
axis 246. Cylindrical body 240 may be a circular cylindrical body or a non-
circular
cylindrical body, for example, a polygonal cylindrical body, such as body
having a
triangular, square, pentagonal, hexagonal, or octagonal cross section, among
others,
having a plurality of flat sections, that is, "flats."
[0089] Second end 242 includes a face 248 adapted to contact the face of inner
race 15
(see FIGURE 11). Body 240 includes a threaded through hole or bore 250
directed
substantially along the longitudinal axis 246 of body 240. The threads of
through
hole 250 may comprise any conventional UN, UNC, UNF, UNJ, Acme, or other
conventional thread. In one aspect, of the invention where nut 220 is used for
a
conventional truck axle, threaded through hole 250 may have 12 to 18 threads
per inch
UN threads.
[0090] According to aspects of the present invention, second end 242 of body
240 may
include at least one recess 252 in face 248. As described above, recess 252 in
the face
248 exposes at least a portion of the mating surface against which nut 220
bears whereby
a compressive load may be applied, for example, to apply a compressive load to
the face
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CA 02576337 2013-10-02
of inner race 15 of bearing 16 (see FIGURE 11). As described above, this
exposure of
the face of race 15 permits a mechanic to apply and/or verify a preload on
bearing 16, for
example, to verify a preferred "3 thousandths" preload discussed previously.
[0091] In the aspect of the invention shown in FIGURES 15 and 16, recess 252
is
shown as a single annular or arcuate recess whereby a raised boss 254 is
provided on
second end 242. However, according to one aspect of the invention, the at
least one
recess 252 may comprises one or more cavities in surface 248, for example, one
or more
cavities evenly distributed about the perimeter of the second end 242. For
instance, in
one aspect of the invention, recess 252 may comprise a plurality of arcuate
recesses
evenly distributed about the perimeter of second end 242 and adapted to expose
the
surface of the mating surface, for example, whereby two or more extensions on
adapter 210, for example, extensions 212, 213 in FIGURE 12, may contact the
mating
surface, for example, the mating surface of bearing 16. As shown in FIGURE 16,
the
diameter of boss 254, or the inside diameter of the plurality of recesses in
second end 242
may have a diameter 255. According to one aspect of the invention, diameter
255 is
sized to provide sufficient support for inner race 15 while providing at least
some
exposure to the surface of race 15 whereby a loading device, for example,
adapter 210,
may contact inner race 15. For example, diameter 255 may be at least as large
as the
minimum "backing diameter" recommended by the manufacturer of bearing 16.
[0092] As shown in FIGURES 15 and 16, first end 241 of body 240 may be adapted
to
accommodate a nut locking mechanism, for example, the nut locking mechanism
disclosed in co-pending and commonly-assigned application 11/029,531 entitled
"Lock
Nut System" filed on January 5, 2005. For example, first end 241 of body 240
may
include a counter bore 256 having a plurality of internal projections 258 and
an annular
groove 260. Internal projections 258 may be gear teeth or spline teeth adapted
to engage
a locking device (not shown) and annular groove 260 may be adapted to retain a
locking
device retainer (not shown), such as described in co-pending application
11/029,531. In
one aspect of the invention, no counter bore 256 or annular groove 260 may be
provided
in first end 241 whereby first end 241 may only comprise a flat surface
interrupted by
threaded through hole 250.
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CA 02576337 2007-01-25
[0093] Body 240 may also be adapted to be engagable by a tool, for example, a
crescent wrench, spanner wrench, or socket, among other tools, whereby body
240 may
be rotated as desired. In one aspect, as shown in FIGURES 15 and 16 body 240
may
comprise an outside surface 262 having at least one flat 264, but typically a
plurality of
flats 264 adapted to engage a tool, such as a wrench or socket. In another
aspect,
body 240 may include at least one recess, hole, or slot adapted to engage a
spanner-type
tool. For example, in one aspect, outside surface 262 may include holes or
slots (not
shown) adapted to engage a spanner wrench. In another aspect of the invention,
any
other surface of body 240 may include recesses, holes, or slots adapted to
engage a
spanner-type wrench, for example, the surface of end 241 may include a
plurality of
equally spaced holes or the surface of counter bore 256 may include a
plurality of equally
spaced holes. Other adaptations of body 240 to facilitate engagement by a tool
for
rotating nut 220 will be apparent to those of skill in the art.
[0094] Nut or fastener 220 may be fabricated from any one or more the
structural
metals mentioned above, for example, carbon steel or stainless steel. Nut 220
may be
fabricated by machining from a billet or plate, by forging or casting and then
finished
machining, or fabricated by conventional powder metallurgy techniques. In one
aspect,
when formed by powder metallurgy, the material may be FC 0208, or its
equivalent. Nut
220 may also be surface hardened for example, induction hardened, carburized,
or
nitrided, among other surface hardening methods; in one aspect, the exposed
surfaces on
end 241 of nut 220 may be hardened, for example, induction hardened.
[0095] One method of providing a preload to an axle bearing and minimizing the
likelihood of losing the preload is to provide a nut arrangement including a
first load
adjusting nut, a lock washer that prevents the load adjusting nut from
loosening, and a
second jam nut that bears against the lock washer to secure the lock washer in
place.
Such a hardware arrangement can be found in most conventional original
equipment
truck and trailer axles. However, in this prior art arrangement, the first
load adjusting nut
is typically at least as large in diameter as the inner race of the bearing to
which it
applied. Therefore, when employing such prior art nut arrangements, the inner
race is
typically not accessible by a bearing loading or verification device, such as
aspects of the
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CA 02576337 2007-01-25
invention. However, the aspect of the invention shown in FIGURES 17-19
addresses the
limitations of the prior art bearing loading devices by, among other things,
allowing
access to the inner bearing race for loading and/or preload verification when
a nut-lock
washer-jam nut arrangement is provided.
[0096] FIGURE 17 illustrates still another aspect of the invention for
applying or
verifying a load or preload to a bearing. FIGURE 17 is a side elevational
view, partially
in cross section, of an apparatus 300 for applying or verifying a load or
preload on a
bearing according to another aspect of the invention. FIGURE 17 is a view
similar to
FIGURE 11 and includes many of the structures that may have similar if not
identical
functions to those structures that appear in FIGURE 11. These similar
structures are
identified in FIGURE 17 by the same reference numbers shown in FIGURE 11. Some
of
these common structures shown in FIGURE 17 include wheel hub 12, shaft 14
(shown in
cross section in FIGURE 17), inner bearing 16 having inner race 15, and means
244
having shaft 40, coupling 46, nut 48, gage 60, and adapter 210. According to
this aspect
of the invention, apparatus 300 also includes a nut or fastener arrangement
270 that is an
alternative to nut 220 shown in FIGURE 11. Nut arrangement 270 includes a
first
internally threaded ring 272, a second ring 274, and a third threaded ring
276. According
to this aspect of the invention, nut arrangement 270 provides a means for
ensuring a
preload is maintained in bearing 16 while minimizing or preventing the removal
of this
preload, for example, during normal operation of the vehicle. In addition,
arrangement
270 also provides access to inner race 15 whereby a bearing loading device,
such as
adapter 210, may access the surface of inner race 15 to provide a desired load
or preload
to the inner race 15. For example, close examination of FIGURE 17 with nut
arrangement 270 installed, illustrates how a surface of inner race 15 can be
contacted by
extensions 212 of adapter 210.
[0097] FIGURE 18 is a perspective view, partially in cross section, of nut
arrangement 270 shown in FIGURE 17. FIGURE 19 is an exploded perspective view
of
the elements of nut arrangement 270 shown in FIGURES 17 and 18. As shown in
FIGURES 18 and 19, nut arrangement 270 includes a first threaded ring or nut
272, a
second ring 274, and a third threaded ring or nut 276. As noted with respect
to diameter
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CA 02576337 2007-01-25
255 of nut 220 in FIGURE 16, the outer diameter of ring or nut 272 may have a
diameter
sized to provide sufficient support for inner race 15 while providing at least
some
exposure to the surface of race 15 whereby a loading device, for example,
adapter 210,
may contact inner race 15. For example, the outer diameter of ring or nut 272
may be at
least as large as the minimum "backing diameter" recommended by the
manufacturer of
bearing 16.
100981 Ring or nut 272 includes internal threads 273 adapted to threadably
mount to
shaft 14 and engage the inner bearing race 15 (see FIGURE 17). Ring or nut 272
includes an outer surface 278 that may be engagable by a tool, for example, a
crescent
wrench, spanner wrench, or similar tool. For example, as shown in FIGURES 18
and 19,
the outer surface 278 of ring or nut 272 may include one or more grooves 279
engagable
by a spanner-type wrench. Grooves 279 may also be slots, notches, holes, or
other
indentations in surface 278. In lieu of or in addition to grooves 279, the
outer surface 278
of ring 272 may include projections, for example, one or more spokes,
engagable by a
tool or a mechanic. Also, according to an aspect of the invention, ring or nut
272 may
have an outer diameter that is less than the outer diameter of inner race 15,
that is,
whereby at least a portion of the longitudinal surface of race 15 is
accessible for contact
by, for example, adapter 210 (again, see FIGURE 17). Ring or nut 272 may also
include
means for engaging ring 274 to prohibit relative movement, specifically
relative
rotational movement, between ring 272 and ring 274. For example, as shown in
FIGURES 18 and 19, ring 272 may include one or more projections or pins 280
adapted
to engage a hole or a recess in ring 274. Pin 280 may be press or shrink fit
into ring 272
or pin 280 may simply be punched into ring 272. In one aspect of the
invention, ring 272
may include a hole or a recess that accepts a projection or pin in ring 274.
Threads 273
may be any one of the threads mentioned above, but are typically 12 to 18
threads per
inch UN threads.
[0099] Second ring 274 is also adapted to mount to shaft 14 (see FIGURE 17)
and
includes means for engaging ring 272 to prohibit relative movement between
second
ring 274 and first ring 272 and second ring 274 includes means for engaging
shaft 14 to
prohibit relative movement between second ring 274 and shaft 14, specifically
prohibit
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CA 02576337 2007-01-25
rotational movement. For example, as shown in FIGURES 18 and 19, ring 274 may
include one or more holes or recesses, for example, through holes 282. Through
holes 282 are adapted to engage one or more pins or protections 280 in ring
272 to
prohibit relative rotational movement between ring 274 and ring 272. Again, in
one
aspect, ring 274 may include one or more pins or projections, similar to pin
280, that are
adapted to engage one or more holes or recesses in ring 272. The means for
engaging
shaft 14 in ring 274 may comprise any recess or projection adapted to engage
shaft 14.
For example, as shown in FIGURES 18 and 19, ring 274 may include one or more
projections or key-type structures adapted to engage a recess in shaft 14. For
example,
ring 274 may include one or more key-type projections 284 that are adapted to
engage a
slot or keyway 285 in shaft 14 (see FIGURE 17). In one aspect, arrangement 270
may
include one or more separate individual keys that are adapted to engage one or
more
keyways in ring 274 and one or more keyways 285 in shaft 14.
[00100] Third threaded ring or nut 276 includes internal threads 277 adapted
to
threadably mount to shaft 14 and engage second ring 274 (see FIGURE 17). Ring
or
nut 276 includes an outer surface 286 that may, similar to ring 272, be
engagable by a
tool, for example, a crescent wrench, spanner wrench, or similar tool. For
example, as
shown in FIGURES 18 and 19, the outer surface 286 of ring or nut 276 may
include one
or more flats 287 engagable by a crescent-type wrench. In one aspect outer
surface 286
may also include grooves, slots, notches, holes, or other indentations
adaptable to be
engaged by a spanner-type wrench. Threads 277 may be any one of the threads
mentioned above, but are typically 12 to 18 threads per inch UN threads.
[00101] Ring 272, ring 274, and ring 276 may be fabricated from any one or
more the
structural metals mentioned above, for example, carbon steel or stainless
steel. Ring 272,
ring 274, and ring 276 may be fabricated by machining from a billet or plate,
by forging
or casting and then finished machining, or fabricated by conventional powder
metallurgy
techniques. In one aspect, when formed by powder metallurgy, the material may
be FC
0208, or its equivalent. Ring 272, ring 274, and ring 276 may also be surface
hardened
for example, induction hardened, carburized, or nitrided, among other surface
hardening
methods.
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CA 02576337 2007-01-25
[00102] As shown in FIGURE 17, according to one aspect of the invention, nut
arrangement 270 may be used to secure bearing 16 to shaft 14 while also
providing
access to the surface of inner race 15 of bearing 16 whereby a bearing loading
device
may contact inner race 15. In one aspect, during a new installation or during
servicing of
an existing bearing, arrangement 270 permits access to inner race 15 by, for
example,
loading adapter 210. In an original installation, after bearing 16 is mounted
to shaft 14
and hub 12, ring 272 may be threaded to shaft 14 and tightened, for example,
hand
tightened, against the exposed longitudinal surface of inner race 15. The
bearing loading
apparatus 244 may then be mounted to shaft 14 as described above, for example,
where
rod 40 is engaged with shaft 14 by means of collar 46, adapter 210 is mounted
to rod 40
and inner race 15, and housing 52 (having piston 54) and nut 48 are mounted to
rod 40.
Then, according to aspects of the invention, a load may be applied to inner
race 15, for
example, mechanically by turning nut 48 and/or hydraulically by introducing a
pressurized fluid to housing 52. The loading on inner race 15 may be
monitored, for
example, by means of pressure gauge 60, until the desired loading on inner
race 15 is
provided. After a load is applied to race 15, the hub assembly 12 may be
rotated about
shaft 14 to ensure proper seating of the rollers of bearing 16. This rotation
and seating
may be practiced repeatedly to ensure proper seating. According to aspects of
the
invention, with the desired loading on inner race 15 provided, ring or nut 272
may be
tightened, for example, by using a spanner wrench engaging grooves 279, to
maintain the
desired loading on inner race 15.
[00103] In one aspect, the rollers in bearings 16 and 18 may be properly
seated by
applying a roller-seating load to the inner race 15, that is, a load
sufficient to seat the
rollers in bearings 16 and 18. For example, a roller-seating load may
correspond to a
hydraulic pressure in housing 52 of between about 900 psig and about 1000
psig, as
detected by gauge 60. (In one aspect, this hydraulic pressure may correspond
to a
bearing load of between about 5000 pounds to about 6000 pounds, for example,
as
computed by Equation 1.) Again, hub 12 may be rotated one or more times while
this
seating load is applied to ensure proper seating of all the rollers. After
proper seating of
the rollers, the applied load may be reduced to a load corresponding to the
desired
preload on the bearings, for example, a load providing a few thousands inches
preload.
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CA 02576337 2007-01-25
This desired preloading may be provided by between about 50 psig and 100 psig
hydraulic pressure in housing 52 of means 244. (In one aspect, this hydraulic
pressure
may correspond to a bearing load of between about 300 pounds to about 600
pounds, for
example, as computed by Equation 1.) Once the desired preload is provided,
ring or nut
272 may be tightened, for example, by hand or with a tool, to maintain the
desired
preload.
[00104] Apparatus 244 is then removed, and ring 274 can be mounted to shaft 14
whereby at least one through hole 282 engages one or more pins 280 on ring 272
and
key 284 engages keyway 285 in shaft 14. These interferences of ring 274 with
ring 272
and shaft 14 substantially prohibit relative rotational motion between ring
272 and
shaft 14 whereby the preload on inner race 15 is substantially maintained.
Then, ring or
jam nut 276 is threaded onto shaft 14 and tightened against ring 274 to secure
ring 274 to
shaft 14. Other procedures and procedural modifications of this method will be
apparent
to those of skill in the art.
[00105] In another aspect, the preloading on a bearing of an existing hub
assembly may
be verified or evaluated with the wheel in place or removed. In this aspect of
the
invention, nut arrangement 270 may be mounted to shaft 14 whereby a preload
may or
may not be present on inner race 15 of bearing 16. Third ring 276 and second
ring 274
may be removed to obtain access to ring 272 whereby ring 272 may be rotated
about
shaft 14, if necessary. In one aspect, where sufficient play between hardware
is provided,
third ring 276 and second ring 274 need not be removed. Also, when a nut such
as nut
220 in FIGURE 11 is provided with a locking mechanism (for example, the
locking
mechanism disclosed in pending U.S. application 11/029,531), the locking
mechanism
need not be removed when sufficient play is available between hardware to
detect
loosening of the nut.
[00106] Apparatus 244 having rod 40, adapter 210, housing 52, and nut 48 may
then be
mounted whereby adapter 210 engages inner race 15. According to aspects of the
invention, inner race 15 may be contacted by adapter 210 since the outer
diameter of
ring 272 is less than the outer diameter of inner race 15. The loading on
inner race 15 is
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CA 02576337 2013-10-02
then gradually increased, either mechanically or hydraulically. At the same
time or
alternating with the increase in load, the tightness of ring 272 against inner
race 15 may
be checked, for example, manually, to determine when the preload on inner race
15 is
relieved by the applied load via adapter 210. If nut or ring 272 becomes loose
prior to
achieving the desired preload for the specific bearing, the preload can be
increased to the
desired value, for example, as indicted by gauge 60, and then ring 272
tightened to
maintain the desired preload. If the preload on inner race 15 is satisfactory,
that is, nut or
ring 272 does not loosen until about the desired preload is achieved, nut or
ring 272 can
be tightened to maintain the desired preload. Should the actual preload exceed
the
desired preload, the load applied by apparatus 244 can be increased until ring
or nut 272
becomes loose, and then the load reduced to the desired preload, and nut or
ring 272
retightened to maintain the desired preload. Apparatus 244 may then be removed
and
rings 274 and 276 remounted according to the invention to ensure the desired
preload is
provided.
[00107] Again, the inventor underscores that though aspects of the present
invention
were described above with respect to their application to wheel hub
assemblies, for
example, truck wheel hub assemblies, it is understood that aspects of the
present
invention may be applied to any vehicle, machine, or component having at least
one
bearing.
[00108] The scope of the claims should not be limited by the preferred
embodiments set
forth in the examples, but should be given the broadest interpretation
consistent with the
description as a whole.
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