Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to improved means
for locating t~e end of a link of a vehicle suspension
or steering system. More specifically, the invention
provides an improved spigot assembly for attaching the knuckle
of a vehicle suspension member to a relatively movable
part of the vehicle, and has particular application to torque
rods and radius rods used in vehicle suspension systems.
Many vehi`cle suspension systems have members
which transmit tension or compression between relatively
movable parts. Such members usually have a knuckle at
one end surrounding a generally cylindrical bushing which is
located by a spi`got or pin connected to the parts to be located
the assembly allowing pivoting of the member about the pin
or spigot~
As an example, my prior Canadian Patent Number
958,729, issued December 3, 1974, shows vehicle suspensions
having lower torque rods connected to suspension parts by
various means. An example of a spigot type, or single ended
type connection is shown in Figure 3 of this prior patent,
the spigot being of a projecting part of a hollow pin which
has a hardened chrome finish with a smooth machined and
polished surface, and which is held within an accurately
machined bore within a suspension part. The pin receives a
hollow bushing held within the knuckle end of a torque rod,
which is held on the pin by a washer and a transverse screw
Another arrangement is shown in Figure 9 of this patent, where
the end of a torque rod is held in a clevis in part by a
hollow pin which is also hardened and machined, and with a
polished surface, and which fits within accurately machined
bores in the sides of the clevis, being retained in place by
a screw.
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These constructions of my prior patent are
relatively expensive in that they necessitate machining and
plating of the pins and machining of the bores into which they
fit, since the pins must fit with very close tolerance within
the bores to avoid any slackness. The provision of transverse
bores for the retaini`ng bolts also adds to the expense.
My Canadian Patent No.1,06g,7~4 issued
December 25, 1g7g,describes an improved spigot assembly
for attaching the knuckle of a vehicle suspension
member to a relatively movable part of the vehicle which
includes a spigot part and a cap part, arranged to be held
together by bolt means. The spigot part has a base arranged
to be rigidly secured to the vehicle part and has a generally
cylindrical projection and an annular bearing surface
extending outwardly from the foot of the projection, the
projection also having frusto-conical surface coaxial
with its cylindrical surface and facing axially outwardly
of the projection. The cap part also has a frusto-conical-
surface, which is complementary to and engagable with that
of the spigot part, and the cap part also has an annular
bearing surface coaxial with its frusto-conical surface and
which faces the bearing surface of the spigot part when the
two parts have their frusto-conical surfaces engaged. The
spigot and cap parts both have axial bores for receiving
the bolt means, and the parts, when fastened together,
are suitable for locating a bushing held by the knuckle of
the suspension me~ber.
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The above described structure has been found to be
cheaper in manufacture and assembly than that of the earlier
patent and those previously in general use and it has been
furthermore found that the parts of the above assembly can be
removed and replaced with relative ease. Furthermore, the
above described assembly makes possible the use of as-cast
surfaces enabling machining and plating costs to be substan-
tially avoided. However, although the above described
arrangement has been found to be a substantial improvement
over the prior art, the need for a still further improved
assembly has been demonstrated. For example, although the
frustro-conical surfaces described in Patent 1,068,734
referred to above substantially eliminate the need for
machining, it has been found that under stress and with
commercial tolerances, there is sometimes a slight tendency
for the cap portion to rock slightly or to wobble relative
to the spigot part thus resulting in undesirable bending
stresses in the connecting bolt. There is accordingly a need
to provide an improved assembly which ensures that the
connecting bolt is only subjected to pure tensile loadings.
There is also a need to provide a spigot and cap configuration
which provides for radial compression and preloading of the
rubber bushing upon assembly. It has also been found that
there is a need to provide a spigot assembly which is somewhat
easier to assemble and disassemble than in the previous
arrangement.
Accordingly the present invention provides for an
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improved spigot assembiy for attaching a knuckle of a vehicle
to a relatively movable part of the vehicle by way of a
bushing having a bore and ends adapted to be held within the
knuckle. The major parts of the assembly include a spigot
part having a base arranged to be rigidly secured to the
vehicle part anda projection extending from the base. The
projection includes a first pair of annular surfaces facing
axially outwardly of the projection and having a bore coaxial
with the first pair of annular surfaces, the annular surfaces
being spaced apart along the bore. A cap part is provided
having a second pair of annular surfaces complementary to and
engageable with those of the projection and having a bore
coaxial with the annular surfaces of the cap part~ Bolt means
are receivable in the bores for fastening the spigot and cap
parts tightly together with the first and second pairs of
the annular surfaces engaged with one another. These first
and second annular pairs of surfaces, by virtue of their
axially spaced relationship, serve to transmit any bending
moments applied by the bushing to the cap part directly to
the spigot part so that the bolt means is not subjected to
bending stresses.
Preferably each of the first and second pairs of
annular surfaces lies generally in a frusto-conical surface
coaxial with the bores thereby to provide a wedgingeffect to
eliminate any rocking motion of the cap part relative to the
spigot part under the influence of bending moments.
In a typical embodiment of the invention, the
projection has a recess defined in part by the first pair of
annular surfaces and the cap has an extension thereon defined
in part by the second pair of annular surfaces, which extension
fits into the recess in the projection. The cap part is
provided with a recess as well and the bolt extends through the
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bores in the projection and the cap part with a nut being
disposed on the bolt and protected within the recess of the
cap part.
In a typical embodiment of the invention, the
projection and the cap part together define outer surfaces
coaxial with the pairs of annular surfaces, with each of the
projection and cap parts further having an annular flange
extending outwardly of and coaxial with the outer surface
and arranged such that in use, with the projection and cap
parts fastened together, the outer surface and the annular
flanges engage the bore and ends respectively of the bushing
which is held within the knuckle thereby to securely locate
the bushing.
In a preferred feature of the invention, the outer
surfaces on the projection and cap parts are tapered inwardly
in directions away from their associated annular flanges so that
as the two parts are brought together, as during assembly thereof,
the rubber bushing becomes compressed (particularly in a radial
direction) between the outer surfaces of such parts and the
knuckle.
Preferably, the outer surfaces of the projection
and cap parts are of substantially equal axial extents.
The projection and cap parts are preferably in
the as-cast condition. By virtue of the structure broadly
described above, no machining of the mating surfaces is
necessary in order to provide a secure and stable structure.
A preferred embodiment of the invention will be
described in detail with reference being had to the accompanying
drawings in which:
Fig. 1 is a diagrammatic plan view showing a
small part of a suspension assembly utilizing the spigot
assembly of the invention;
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Fig. 2 shows a detail of a portion of Fig. 1 in
which a part of the spigot assembly and associated end of
the torque rod are sectioned and,
Fig. 3 is an end elevation view of the structure
illustrated in Fig. 2.
As noted previously, the present invention finds
use in various forms of suspension systems, which
systems involve use of torque rods or like members to provide
an interconnection between the vehicle frame and a relatively
movable part of the suspension.
Fig. 1 shows a small part of a suspension
assembly incorporating a spigot assembly according to the
invention and includes an elongated rod 10 having at its end
an enlarged eye or knuckle 12 in the form of a short cylinder
transverse to the rodt and having a bore which is of convergent-
divergent form as shown in Figure 2 and which is cast on the
end of the rod 12, such knuckle ordinarily requiring no
machining. Into this bore is inserted a resilient elastomeric
bushing 14, preferably of rubber, having an outer shape
conforming to that of the transverse bore. The inner surface
of bushing 14 is located by the improved spigot assembly
generally indicated by reference 16.
Referring to Fig. 2/ the spigot assembly is shown
as including/ basically/ a spigot part 18, a cap part 20,
and bolt means 22 which hold the two parts together.
It will be seen that the spigot part 18 is a
casting having a flat outwardly flared base 23 which, as
shown in Fig. 2, may be attached by weld 21 to a chassis
member 26. A hollow tubular projection 24 extends outwardly
from base 23/ the projection 24 being of circular cross-section.
Projection 24 has an internally disposed annular lip 25 thereon
and this lip 25 in combination with the inwardly directed
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surface of end portion 28, serves to define a flrst pair of
annular surfaces 30 and 32 which face generally axially out-
wardly of the projection 24. The hollow interior of the
projection defines a relatively large bore coaxial with the
first pair of annular surfaces 30 and 32 and it will be seen
that the pair of annular surfaces 30 and 32 are spaced apart
axially along such bore.
The cap part 20 is provided with an extension 34
thereon which extends into the recess defined within the
projection 24. This extension 34 is defined in part by a
second pair of annular surfaces 36 and 38 which are complementary
to and engageable with annular surfaces 30 and 32 respectively
of the projection. The cap part 20 also has a bore 40 defined
therein which is coaxial with the annular surfaces 36 and 38.
The previously noted bolt 22 extends axially through
the spigot part 18 and through the bore 40 in the cap part
thereby holding the first and second pairs of annular surfaces
30, 36 and 32, 38, tightly engaged with one another. It will
be readily seen from Figure 2 that the first and second pairs
of annular surfaces lie generally in a frusto-conical surface
coaxial with the above noted bores in the spigot part 18 and
cap part 20 thereby to provide a wedging effect to eliminate
any tendency for the cap part 20 to rock to and fro relative
to the spigot part 18 under the influence of bending forces.
In the embodiment shown in Fig. 2 the angle of this conical
surface to the axis of the bolt 22 is about 20~ although this
angle, it should be realized, can be varied substantially while
still providing good resl~lts.
With continued reference to Fig. 2, both the
spigot part 18 and the cap part 20 are provided with respective
outer surfaces 46 and 48 coaxial with their respectively
associated pairs of annular surfaces 30, 32 and 36, 38 with
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each of the spigot and cap parts 18 and 20 further including
respective annular flanges 50 and 52 extending out~ardly of
and coaxial with their associated outer surfaces 46 and 48
and arranged so that, in use of the spigot assembly with the
parts 18 and 20 fastened together by bolt means 22, the outer
surfaces 46, 48, and the annular flanges 50, 52, engage the
bore and ends respectively of the rubber bushing held within
the knuckle. It should also be noted that the a~ove annular
flange 50 serves to also define the above noted outwardly
flaring base portion 23 which is welded to the frame member
26 although it will be realized that a separate base portion
could be provided.
As a further significant feature, the outer
surfaces 46 and 48 defined by the spigot and cap parts 18 and
20, are tapered inwardly (i.e.have gradually decreasing diameters)
in directions inwardly from their annular flanges so that as
the two parts 18 and 20 are brought together, as during assembly,
the rubber bushing 14 becomes radially compressed between the
outer surfaces 46 and 48 and the knuckle 12. In the embodiment
illustrated the outer surfaces 46 and 48 of the spigot
and cap parts are of substantially equal axlal extent.
It will also be noted that the cap part 20
has an outwardly facing recess 56 therein which is coaxial
with the bore 40. With the bolt 22 in position as shown in
Fig. 2, the nut as well as the threads of the bolt are disposed
deep within this recess 56 thus protecting the nut and the
bolt threads from damage as well as allowing the bolt to be
kept short.
The above described arrangement is very simple to
install. Firstly the spigot part 18 is welded around the
periphery of base 23 (as defined by flange 50) with a suitable
aperture 60 being provided in the frame member 26 through whlch
bolt 22 can be passed. The knuckle 12 with a bushing 14 therein
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is then located on the projection 24 of the spigot, as shown
in Fig. 2, and the cap 20 is then placed in position also as
shown in Fig. 2. The nut is then put in place on bolt 22
and tightened until the complementary axially spaced annular
surfaces 30, 36 and 32, 34 are drawn tightly together.
Although both the spigot and cap parts are in as-cast
condition, so that the above axially spaced annular surfaces
do not mate exactly, nevertheless it has been found
that they mate sufficiently well for the two parts to be
held in secure alignment with one another.
The rubber bushing 14 is dimensioned so that when
held by the knuckle 12 and axially uncompressed, it can
slide easily onto the spigot projection 24 and cap 20 easily
inserted into it. However, when the spigot and cap are drawn
together by bolt means 22, the bushing 14 is both axially
and radially compressed to such a degree that the bushing
does not normally slide relative to these surfaces but is
sufficiently deformable to allow the normal movements in the
suspension without sliding. However, unusually large
movements will allow the rubber to slip until it reaches a
neutral position.
For replacing the bushings in a torque rod,
all that is requi~ed is removal of the nut from bolt 22
whereupon the rod and cap 56 are removed and the knuckle
replaced with a new bushing. There is usually sufficient
spring in the rubber bushing for the spigot assembly to be
t~ghtened up completely at one end, while the other end of
the torque rod remains to be sprung onto its spigot.
Preferably however, the ends of the torque rod are placed
on the respective spigots before anytightening takes place.
The above described embodiment possesses a
substantial number of advantages. "As-cast" or "as-forged"
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parts may be used,and the necessity for machining or finishing
of parts is eliminated thus reducing substantially the
manufacturing costs involved.
Both the spigot and cap are hollow thus saving
material costs and weight while providing for adequate
strength. The relatively generous exterior dimensions
minimize the pressure on the rubber bushings.
The spigot projection is only about half the
length of the completed assembly. Upon removal of the cap,
the torque rod or link only has to be moved about half the
bushing length to allow it to come off the spigot. This
provides for ease of assembly or disassembly particularly
when one is working with relatively short torque rods. The
taper on the spigot projection also assists in the disassembly.
The tapered external surfaces of the spigot and
cap, which complement the interior surfaces of the bushing,
result in radial compression and loading of the bushing upon
assembly.
By virtue of the axially spaced apart mating
annular surfaces, the connecting bolt is only subjected to
tensile loadings. The annular mating surfaces take up all
of the bending moments. Therefore much smaller bolt diameters
can be used thus resulting in less weight and less cost. The
bolt can usually be of a common commercially available variety
and not of a special construction as is often required in
cases where the bolt is subjected to substantial bending or
shearing loads.
The dimensions and tolerances of the spigot, the
cap and the rubber bushings, control the amount of precompression
~ of the rubber bushing. The human element is eliminated and
accordingly the bushing cannot be over-tightened or crushed~
The assembly is relatively compact. There is
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no need for a fastener, i.e. a nut, extending beyond the end
of the spigot joint and the bolt threads and nut are fully
protected. This is particularly important in the case of
heavy equipment. Another feature is that the design permits
different materlals for the different parts. For example
the spigot may be made of high tensile alloy steel while the
cap is made of a relatively inexpensive mild steel.
