Note: Descriptions are shown in the official language in which they were submitted.
CXGROUN~ OF THE INVENTICN 11~343
This invention relates to improvements in braking apparatu5
and more particularly, but not by way of limitation, to an improved
disc brake assemoly for off highway vehicles having very large wheels.
.
Extremely large off-highway vehicles are becoming widely used
in many industries, such as in the mining industry, the large
construcfion industry, and the like. The excessive size and weight of
these vehicles has created many problems in the construction and
operation thereof for both efficiency and safety purposes. Of course,
the wheels of these vehicles are exceptionally large, usually
requiring tires in excess of ten feet in diameter. It is frequently
advantageous to mount at least the front wheels of the vehicle
independently, and it is prefera~le to provide a disc brake system for
each wheel, operable independently of one another~ During a braking
operation, it has been found that the disc generates a considerable
amount of heat, and the metallic material from which the disc is
constructed frequently ~seizes~ the elements to which it is secured,
or fuses thereto, and as a consequence, it is difficult, if not
impossible, to remove the disc for replacement or repair. ~sually,
the disc is completely destroyed during remov~l thereof, which is an
obvious disadvantage. In order to remedy this difficulty, an annular
groove is frequently provided on the op~osite faces of the brake disc
in order to dissipate the heat. In actual use, however, it has been
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~ound that the groove disposed inboard or on the ~ngaging ~ace of ~he
disc is less effecti~e for hea~ dissipation than originall~ thought,
since it is covered ~y the braking surface of the stationary brake
elements, and the outboard groove is so far removed ~rom the heating
area that effective heat dissipation is difficult. In addition, the
driving wheels of these large vehicles are frequently powered b~ a
; wheel motor disposed within a wheel rim and the brake disc is often
operably connected with the armature of the motor. Because the
armature is connected to the wheel through a gear train, the brake
1~ disc is caused to rotate at a relatively high rate of speed, or a high
~EM. Thus, oonsiderable braking effort is necessary for an efficient
braking operation, and the truck m~y be vulnerable to a brake failure
due to a gear train failure.
Furthermore, during ~evere conditions of usage, disc-brakes
1~ can get extrem~ly hot, after which they subsequently cool betweenuses. In aggravated situations, this activity results in substantial
expansion and c~ntraction, and if the disc is rigidly attached at its
outer periphery-by bolting or such, this expansion and contraction can
result in broken or warped parts.
SUMMA~Y OF THE INvENrIoN
.
The present invention relates to a
novel disc brake and wheel assem~ly particularly designed and
constructed for overcoming the foregoing disadvantages in the braking
systems of off-high~ay vehicles, ~o improve overall braking effiency,
and ~o eliminate problems o broken or warp~d parts d~æ to expansion
and c~ntraction of the brake disc~ Each embcdiment illustrated herein
generally comprises an annular brake disc nenb~ mounted on carrier
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means secur~d to a rotatahle ~heel hub disposed outboaxd, i.e. J
radially outwardly, of stationary brake calipers an~ cooperating
therewith to provide braking action for the vehicle. Since the
brake disc is disposed radially outwardly of the brake calipers
and axially outwardly of the stationary wheel hub, there is
considerably greater heat dissipation. In addition, the brake
disc is carried by the vehicle wheel and ro-tatable simultaneously
therewith. Thus, the ~rake disc rotates at a relatively low RPM
or at least at a lower rotational speed than that in a conventional
armature-type disc brake mounting arrangement, the lower
rotational speed of the disc greatly increasing the br~king
efficiency. Furthermore, the radially outward posltion of the
brake disc provides more operable space for the brake disc, which
results in a greater braking area and also increases the braXing
effiency. All the emhodiments of the novel braking apparatus
~- disclosed herewith are simple and efficient in operation and
; economical and durable in construction.
In two of the illustra-ted embodiments of the
present invention, expansion and contraction o~ the brake disc is
greatly alleviated by having the disc supported for limited
radial and circumferential movement, so as to reduce the chance
of warping or breakage of either the disc or other parts in
severe usage situations.
In accordance with the present invention, therefore,
there is provided an improved wheel assembly for larye, off-
highway vehicles or the like comprising a wheel having a
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central non-rotatable housing section and a radially outer
rotatable wheel section including a rotatable outer hub and a
wheel rim. The wheel assembly comprises drive means mounted
on the central housing for transmitting driving forces to the
outer wheel section. Brake caliper means are mounted on the
central housing section and disposed radially outwardly from the
axis of rotation of th~ outer wheel section, the caliper means
opening radially outwardly from the axis of rotation. The
assembly further includes carrier means mounted on the outer hub
section between the central housing section and the wheel
rim. An annular brake disc is supported by the carrier means
and operably disposed within and radially outwardly of the
brake caliper means~ The brake caliper means are positioned
to contact the brake disc proximate the maximum radius thereof~
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BRIEF DESCRIPTION OF THE DRAWINGS
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Figure 1 is a right front perspective view of an off-
highway vehicle of the type with which a braking apparatus
embodying the invention may be utilized;
~, Figure 2 is a left rear perspective view of the
vehi-le shown i4 Fl~ure
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Figure 3 is a front elevational view, partly in section, of a
brake apparatus emkoæying the invention;
Figure 4 is a view looking ~rom line 4-4 of Figure 3, with a
portion cut away for purposes of illustration;
Figure 5 is a front elevational view, partly in section, of an
alternative e~bodiment of the present invention;
Pigure 6 is a side elevational view of the embodiment shown in
Figure 5 with parts removed;
Figure 6a is a side elevational view of the brake disc of
Figure 6 removed from the assembly of Figure 6;
Figure 7 is a front elevational view, partly in section, of
another alternative embodiment of the present invention;
Figure 8 is a side elevational front view of the embodiment
illustrated in Figure 7;
Figure 8a is a side elevational view of the disc carrier of
Figure 8 removed frcm the ass~mbly;
Figure 8b is a side elevational view of the brake disc of
Figure 8 removed from ~he assembly; and
Figure 9 is a view loGking from line 9-9 of Figure 6.
DE~AILED DESC~IPTIGN OF 1~3E PREFERRE~) EMI~)DIMENT
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Referring to the drawings in detall, referen oe chararter 10
generally indicates an off-highway vehicle comprising a cab section
12, a dump body 14, a pair of ~ront wheels 16 $ndependently unted on
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the opposite sides of the cab section 12 in any suitable manner, as is
well known, and a pair of rear wheels 18 prPferably journalled on the
opposite ends of a co~r,mon axle 19, but not limited thereto. In the
particular embodiment depicted herein, each of the rear wheels 18 is
driven by a suitable electric motor 28 centrally mounted within the
wheel lB, as is well known in this type of vehicle. Ihe front wheels
16 in the embodiment depicted herein, however, are steering wheels and
are usually not power-driven wheels~
Each wheel, such as the wheel 18, comprises a tire ~not shown
in Figures 1-4) and an annular tire retainer 22 disposed around the
outer periphery oi the wheel rim 24, as particularly shown in Figures
5 and 7. Referring to Figure 3, the wheel rim 24 may be of any
suitable type, and normally includes an inwardly directed angularly
disposed annular shoulder 26 extending around the inner periphery
thereof for a purpose as will be hereinafter set forth. ~ suitable
wheel motor generally indicated at 28 is centrally disposed within the
rim 24 and is substantially concentrically arranged with respect
thereto, as is well knownO The motor 28 is normally provided with a
wheel hub element 30 around the outer periphery thereof engageable
with the inner periphery of the wheel rim 24 and rotatable
simultaneously therewith. me wheel hub 30 is journalled on or around
a non-rotatable central core or housing 32 by suitable bearing means
- 34 (a relatively small portion of the housing 32 and bearing means 34
being shown in Figure 3), whereby the hub 30 and rim 24 are freely
rotatable with respe~t to the housing 32. ~he housing 32 is
preferably secured to ~he rear a~le l9 in any suitable manner (not
shown) as is well known~
An adapter ring 36 (Figure 3) is bolted, or otherwise secured
to the outer end Df the housing 32 by ~uitable bolts 38 and is
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provided with a radially inwardly directed circumferential flange 40
for supporting a plurality of spaced brake calipers 42. As shown in
Figure 4, it may be preferable to provide two of the calipers 42, but
there is no intention of limiting the number of calipers to the
particular number shown herein. me calipers may be secured to the
flange 40 in any suitable manner, such as by a plurality of bolts 44,
and are provided with a spaced brake element 46 and 48 selectively
movable in directions toward and away from each other for the
application of and release of braking pressure, as is well known. The
calipers 42 are particularly arranged whereby the space between the
braking elements 46 and 48 is open at the outer periphery of the
calipers 42 for a purpose as will be hereinafter set forth.
.
The ring 36 is provided with a radialy outwardly extending
circumferential flange 50 shown in figure 3. A thrust ring 52 is
lS disposed around the outer periphery of the housing 32 and is secured
to the flange 50 by a plurality of circumferentially spaced bolts 54.
m e adapter ring 36, thrust ring 52 and the calipers 42 are held
stationary with the housing 32, whereas the wheel hub 30 is rotatable
about the central axis of the motor 28. A bearing cap ring 56 is
secured to the outer face of the wheel hub 30 by a plurality of
circumferentially spaced bolts 58, and is rotatable simultaneously
therewith. A suitable dynamic sealing ~ing 60 is interposed between
the thrust ring 52 and the bearing ring 56.
An annular brake disc 62 is interposed between the brake
elements 46 and 49 and extends radially outwardly thereProm. m e disc
62 is removably secured to a substantially cylindrical brake disc
carrier sleeve 64 by a plurality of circumferentially spaced bolts 66.
A radially outwardly extending clrcu~ferential flange 69 is rigidly
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secured to the oFposite end of the ~lee~e 64 and is remcvably secured
to the wheel hub 30 by a plurality o~ circumferentially spaced bolts
69 (Figure 4). In addition, a plurality of circumferentially spaced
wheel clamps 70 are removably secured to ~he wheel hub 30 and flange
68 by a plurality of bolts 72. The wheel clamps 70 facilitate
securing the wheel rim 24 to the motor 28, as is well known, and also
facilitate removal of the wheel rim 24 from the motor 28 when required
for replacement or repair of the tire 22. A cover or hub cap 74 may
be removably secured to the outer periphery of the brake disc 62 in
any suitable conventional manner.
;
The brakes 45 and 48 may be actuated by any suitable means,
electric, pneumatic, hydraulic or otherwise, and are operably
connected with a suitable control mechanism tnot shown) disposed in
the cab section 12 for actuation by the driver of the vehicle 10.
When the brakes 46 and 48 are activated, braking pressure is applied
simultaneously to the opposite faces of the brake disc 62 by
engagement of the braking elements 46 and 48 in a conventional manner.
m e brake elements 46 and 48 and brake calipers 42 are stationary
through the connection with the housing 32, and the brake disc 62
rotates simultaneously with the tire 22 and the wheel rim 24. When
the braking elements 46 and 48 are in forced engagement with the brake
disc 62, the rotation of the disc 62 will be stopped, ~hich will
result in the stopping of the rotation of the wheel rim 24 and tire 20
for pr w iding the braking action for the vehicle 10.
As hereinbefore set forth the brake disc 62 is disposed
outboard or radially outwardly of the brake calipers 42 and generally
axially outwardly of the wheel hub 30, and is spaced from the wheel
rim 24 80 ~hat th2 heat generated by the braking operaticn is readily
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dissipated. In addition, the radially outward disposition of the
brake disc 62 permits ~he utilization of the disc 62 having a greater
` braking area, which urther increases the braking efficiency. Also,
the speed of rotation of the brake disc 62, rotating at the same speed
as wheel 24, is relatively slow, which increases the braking
efficiency3
When it is necessary to remove the wheel rim 24 from the motor
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28 for any reason, the wheel clamping elements 70 may be disconnected
from the tor 28 and the rim 24 may be easily removed for tire repair
or replacement. The procedure may be reversed for replacing the wheel
rim 24 in operable position on the motor 28.
For severe applications, brake disc 62 may alternatively be
' mounted in a less confined manner, as shown in Figures 5 through 9, to
permit circumferential and radial expansion or contraction without
possible attendant warping or breakage of either the disc 62 itself or
~ other parts. Referring to Figures S, 8 and 9, one embodiment of such
-1 a disc brake 100 is shown~ An annular wheel carrier sleeve 110 and
clamps 117 are added to the construction of Figure 3 to replace the
wheel clamps 70 and the carrier sleeve 64 of that embodiment and the
wheel rim 24 is reversed to accommodate the carrier sleeve 110. The
carrier sleeve 110 is attached to the wheel hub 30 by a plurality of
bolts 116, and the clamps 117 are mounted at circumferentially spaced
locations on studs 118 and secured hy nuts 119 (Figure 9) to operably
clamp together the wheel rim, carrier sleeve and wheel hub.
m e brake disc, illustrated at 162, is retained in part by a
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~ radially inwardly extending support flange 11~ on the carrier sleeve
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lla. As shown in Figures 5 and 6a, the brake disc 162 has a plurality
of recesses 164 about the periphery thereof, and the carrier sleeve
110 has a plurality of lugs 114 welded thereto ~Figure 9) at
interruptions in the flange 112 tnot shown) coincident with the
recesses 164, so that the lugs 114 are disposed within the recesses
164. The lugs 114 transmit braking forces between the brake disc and
the wheel.
Brake disc 162 is 1 osely retained in position by a plurality
of generally U-shaped disc holding elements having central portions
1~ overlying the disc 162. Disc hold elements 120 may be disposed at
locations coincident with the recesses 164 of the disc 162, as shown,
or may be positioned elsewhere about the periphery of the disc. The
disc holding elements 120 are secured to the carrier sleeve 110 and
the wheel hub 30 by bolts 116 passing through the holes in the ends
thereofO Spacers 122 are disposed between the disc holding elements
120 and the carrier sleeve 110 so that the disc 162 will Dot be
tightly clamped.
A hub cap sleeve 75 is also illustrated in Figures S and 6,
attached to the disc 162 at tab flanges 76 by bolts 770 The hubcap 74
may be press fit on to the sleeve as shown in Figure 50
Another e~bodiment of the present invention that can permit
limited thermal expansion and contraction is the disc brake 200 shown
in Figures 7 and 80 A modified annular carrier sleeve 210 is attached
to the wheel hùb 30 at a plurality of circumferentially spaced
locations by bolts 2120 The carrier 61eeve 210 interfaces with the
~1heel rim 24 by clamping means 214, comprising a series of studs 216
mounted directly to the carrler sleeve 210 at a plurality of
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circumferentially spaced locations. A plurality of wheel clamps 218
having an arcuate cross-section (Figure 7) are disposed across
adjacent pairs of ~olts 216 ~Figure 8~ and are secured by nuts 220.
The clamps 218 secure the wheel rim 24 to the wheel hub 30. ~he
carrier sleeve 210 has a radially inwardly extending support flange
222 having tapped holes 224 at circumferentially spaced locations. A
retaining ring 226 ~Figure 8a) is attached to the flange 222 of
carrier sleeve 210 by a plurality of bolts 232 disposed in holes 224,
and has a plurality of internally ~ormed radially inwardly directed
lugs 228, each having two holes 230 therethrough.
;
The brake disc 262, illustrated in Figure 8b, has a plurality
of recesses 264 in the periphery ~hereof corresponding in number to
the number of lugs 228 on the retaining ring 2260 The disc 262 is
positioned in the same plane as the ring 226, with lug5 228 disposed
in recesses 264. Ihe ring and lugs have substantially the same axial
thickness as the disc. A pair of disc holding elements 240,
illustrated in Figures 7 and 8, are pDsitioned on opposite sides of
each lug 228 and are mounted thereto by bolts 241 passing through
holes 230, and nuts 242, m e disc holding elements 240 overlie each
2~ lug 228 to prevent undesirable relative axial movement between the
brake disc and retainining ringO
Clearance exists between each lug 228 and the corresponding
recess 264 to permit ther~al expansion and contraction of the disc
262. As in the preYious embodiment, the lugs and recesses trancmit
braking forces between the brake disc and the wheel ri~.
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~` lhe particular sTbodiments OI' the invention depicted may be
utilized in combination with either a single wheel or dual wheel
arrangement, although only a single wheel has b~en illustrated herein.
Whereas the present invention has been described in particular
relation to the dr~wings attached hereto, it should be understood that
other and further modifications, apart from those shown or suggested
herein, may be made within the spirit and scope of the invention.
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