Note: Descriptions are shown in the official language in which they were submitted.
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DISC BRAKE P~D I~SSE~IBI,II:S
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This invention relates to friction pad assemblies
for use in sliding caliper disc brakes.
Commolly, friction pads are supported on guides of
the disc brake, the braking drag forces being transmitted
from the pad to the vehicle frame via the guides. Clearance
is usually provided between the guides and the pad to permit
the pad to slide towards and away from the disc during brake
application and release. To prevent rattling of the pad
on the guides it has previously been proposed to attach to
the pad an anti-rattle spring to bias the pad against the
guide.
A pad assembly incorporating an anti-rattle spring is
illustrated and described in U.S. Patent No. 4,056,174 issued
November 1, 1977 to Wienand et al. The spring shown in that
patent has a coil portion and two arms çxtending outwardly
from the coil portion. The spring is attached to an upwardly
extending projection on the pad backing plate by a pin passing
through the coil portion of the spring.
That pad assembly has proved expensive to produce
because a considerable amount of backing plate material has
to be scrapped during production, which is by a stamping pro-
cess, because the provision of the projection necessitates a
larger blank of material than would otherwise be required.
The quality, and thus the cost of the backing plate material
is necessarily high.
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In an attempt to reduce the amount of scrap material,
it has been proposed to locate the anti-rat-tle spring in a groove
in the backing plate, the pad holding the spriny in position. This
has the disadvantage that -the spring has to be located in the groove
before the friction material is moulded on to the back plate. The
heat required in the moulding process can damage the spring and alter
its characteristics~ Furthermore, we have discovered that when the
pad ~ools the spring remains "fixed" and cannot adjust its position
to allow the pad assembly to align properly in the brake. Such fail-
ure to align creates uneven side loads on the pad causing it to
tilt within the pad guides.
The aim of the present invention is to overcome, or at
least reduce, the above-mentioned disadvantages of previously pro-
posed pad assemblies.
This application is a division of Canadian Application
Serial No. 335,566 filed September 13, 1979.
- The problems of the prior art are overcome by the invention of
the parent application by providing a friction pad assembly comprising a
backing plate having front and rear faces and friction material secured to
the front face, an anti-rattle spring having a bent portion intermed-
iate its ends, and a recess extending across the width of the backing
plate from the front to the rear faces thereof, the recess having an
opening which extends outwardly through the edge of the backing plate
between the front and rear faces thereof the opening being smaller
-than the largest dimension of the recess, the bent intermediate portion
of the spring being seated in the recess and forming a positive connec-
tion ther~with by the inherent resilience of the bent portion, the
recess and the bent portion forming the sole connection between the
spring and the backing plate, the recess being accessible to
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secure the spring to the backincJ plate after the friction
material is secured to the backinc3 plate, the spring being
removable from the recess without deformation of the backing
plate.
On the other hand the invention of this divisional
application overcomes the problems of the prior art by pro-
viding a friction pad assembly comprising: a backing plate
having front a~d rear faces, a t~p edge, and two lateral edges:
projection means extending upwardly from the top edge of the
backing plate, the projection means including a pair of
laterally spaced apart recesses defining therebetween a cen-
tral abutment portion of the projection means and defining
laterally outwardly of the recesses a pair of side abutment
portions of the projection means; friction material secur-
ed to the front face of the backi.ng plate; and an anti-rattle
spring secured to the projection means by means of a bent
region of the spring which passes through the recesses and
forms an interlock fit with the abutment portions.
Several embodiments of th.e invention in the form
of disc brake pad assemblies will now be described, by way of
example, with reference to the accompanying drawings, in
which: -
Figure 1 is a side elevation of one form of assem-
hly,
Figure 2 is a plan view of the assembly of Figure 1,
Figure 3 is a side elevation of the backing plate
of the assembly of Figure 1,
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Figure 4 is a detail perspectiye view of the
backing plate of Figure 3,
E'igure 5 is a si.de elevation of another form
of assembly,
Figure 6 is a cross sectional view taken on
lines 6~6 of Figure 5,
Figure 7 and 8 are views similar to those of
Figure 5 and 6, respectivel~, before attachment of an
anti-rattle spring,
~o Figure 9 is a side elevation of another form of
assembly,
Figure 10 is a detail side view of yet another
form of assembly,
Figure 11 is a view similar to that of Figure 10
of yet another form of assembly,
Figure 12 is a detail transverse sectional view of
the assembly of Figure 11,
Figure 13 is a sectional view similar to that of
Figure 12 of a further form of assembly, and
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~ igure 14 is a detail view showing means for retain-
ing a spring of an assembly.
Each of the forms of pad assembly comprises the
backing plate 1 and a pad 2. The backing plate 1 has later-
ally extending shoulders 3 which are free of friction pad
material and which, when mounted in a sliding caliper disc
brake, are supported on guides. A suitable disc brake for
mounting the pad assemblies described herein is described
- and illustrated in aforementioned U.S. Patent No. 4jO56,174.
The pad assembly of Figures 1 t~ 4 comprises an anti-
rattle spring 4 having a bent portion 5 of rectangular shape
and two outwardly and upwardly extending arms 6. When mount-
ed in a brake, the arms 6 serve to bias the shoulders 3
against their guides to prevent or reduce rattle of the
assembly. Side parts 5A of the bent portion seat in recesses
provided by undercuts 7 formed at the base of an upwardly
extending projection 8 on the backing pla-te 1. The spring
4 is preferably wrapped around the projection in such a
manner that it is difficult to remove the spring from the
projection.
The projection 8 has a depth considerably smaller than
- that of the projection of the pad assembly described in the
U.S. patent identified above, the comparative si~ze of the
last-mentioned projection being
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sho~ in broken lines in Figure 1. The deptll of projection
8 is the minimllm required to provide the undercuts 7.
In the pad assembl~ of ~igures 5 to 8, the
backing plate 1 has a recess formed by a hole 1 which
provides an opening 12 at the top of the plate, the
opening 12 having a width less than the diameter of the
hole 11. A spring 13 havins a circular coil portion 1~
and outwardly extending arms 15 is inserted in the recess
with the plane o~ the coil portion 14 being parallel with
1~ the plane of the backing plate 1.
One side o~ the hole 11 is partially covered
by the pad 2 and the edge of the other side o~ the hole
is inturned after insertion of the spring to form a lip
16. Thus, the spring is prevented from falling out of the
- 15 hole.
In each of the above described emboditnen*s
the bent portion of the spring has at least one complete
turn.
The last-described embodiment has the advantages
over the fixst described embodiment that the 3prinS 13
acts as a true coil sprinS which utilizes the full spring
effect of the coil portion 1t~ hereas in the spring 4 the
resilience is pro~ided by the arms 6, and that the
projection 8 is not required.
~urthermore, the diameter of the coil portion
14 can be so chosen that it is an interference fit in
the hole 11, but that when the spring is laden the
diameter can alter to be smaller than the hole diameter.
Thus, the spring 13 can be readily inserted by loading it
to reduce the diameter o~ coil portion lt~ and then
insertingr the coil portion into the hole. The change in
diameter o~ the coil portion 1~ under load ensures mo~e-
ment of that portion durins use w~1ich preven-ts corrosion
which provides a cleaning effect o~ the hole 1l.
In the assemblies described be]ow the bent
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port;.o~s are only par-t:ially coi.1ed.
The embodiment of ~ig~lre 9 is similar to that
of ~isure 1 and the same numerals are used to denote
similar parts. The bent portion 5 is part~rectangular in
shape and seats in recesses formed hy undercuts 7 at the
base of the upwardly extendins portion 8 of the backing
plate 1. The portion 8 may extend to a greater height and
be tapered to,permit the spring to ba pushed downwardly
over the portion 8.
The bent portion 5 of the spring ~ of the
assembly of ~igure 10 is part-circ~lar and seats in a
part-circular recess 9 whose upper openinS width is less
than the diameter of the recess. I`he plane of the bent
portion 5 is substantially parallel with the plane-of
baclcing plate 1.
Figures 11 and 12 shown an assembly in which the
spring bent portion is substantially part rectangular,
two sides of the portion fitting in recesses 11 formed
- in an ups-tanding portion 8 of the backins plate 1~ In
this form of assenlbly cut-outs 17 are provided on one
side of the portion 8 to ensure that the arms 6 of the
sprin~ do not protrude beyond the plane of the rear sur-
face lA of the backing'plate.
The assembly of Fisllre :l3 is sim:ilar to that of
Fisures 11 ancl 12 except that the cut-outs 17 are not
provided.
Figure 14 illustrates an assembly in which the
spring seats in recesses ~8 in an upstand:ins portion
8 of the backing plate 1 and is retained therein by projec-
tions or lips16. The recesses are preferably locatedclose to the base of the portion 8 so that the heigh-t of
the portion is as small as poss.ible~
In each of the abo~e described embod~ ents it is
possible to arrange the bent portion of the spr:in~ SllCh
that the i.nherent res:ilience o~ tl-le spri.nS ret~;.ns the
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spring in position in the recess. ~urthermore, it will
be appreciated that the spr:ings may be attac}led *o the
backins plate after the pad has been secured thereto, so
that the spring is not subjected to *he hea-t required to
bond *he pad to the backing plate.
It will be appreciated that to accommodate
the larger projection of *he pad assembly described in
said Complete Specification a recess ~as provided in
the caliper bridge of the disc brake and that the above-
described pad assembl:ies require a much s~n~ller recess, ornone at all. Thus, the bridge may be made tnore compact
and/or stronser.
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