Disc brake

A disc brake (10) includes a support member (22) movably interlocking with a pair of friction elements (42, 44) to dispose the friction elements adjacent a rotatable brake disc (12). The friction elements define abutment surfaces (88, 90) movably engaging a caliper (60) straddling the brake disc (12) and friction elements (42, 44) so that the friction elements support the caliper. An axially-extending pin (110) is carried by the support member (22) and received in an axially-extending bore (112) defined by the caliper so that the caliper (60) is also supported by the axially-extending pin. The caliper (60) includes pairs of axially-spaced projections (96, 98, and 100, 102) and the friction elements (42, 44) define slots (92, 94) aligning with the projections. A pair of resilient members (104, 106) extend axially through the slots (92, 94) of the friction members (42, 44) and engage the projections (96, 98, and 100, 102) of the caliper to interlock the caliper (60) and friction elements (42, 44). Another pair of resilient members (118, 120) carried by the support member (22) engage the friction elements (42, 44) to prevent their rattling against the support member. The other pair of resilient members (118, 120) also bias the friction elements (42, 44) away from the brake disc (12).

The invention relates to a disc brake. More particularly, the invention 
relates to a disc brake of the type including a rotatable brake disc 
having friction faces thereon. A caliper includes a pair of legs 
straddling the brake disc and cooperating with a pair of friction elements 
to urge the friction elements into engagement with the friction faces of 
the brake disc. A non-rotatable support member movably carries the 
caliper. The support member substantially prevents radial and 
circumferential movement of the caliper while allowing axial movement of 
the caliper relative to the brake disc. 
Accordingly, this invention relates to a disc brake comprising a brake disc 
rotatable about an axis, a nonrotatable support member including a pair of 
circumferentially spaced and axially extending arms defining a recess 
therebetween, a pair of friction elements received in said recess adjacent 
opposite faces of said brake disc and engaging said pair of arms in 
torque-transmitting abutting relationship, and a caliper received in said 
recess and straddling both said pair of friction elements and said brake 
disc. 
A sliding caliper disc brake is known in accordance with the U.S. Pat. No. 
4,027,751, (hereinafter '751) issued June 7, 1977 to J. Gerard wherein a 
support member carries a pair of circumferentially spaced, 
axially-extending pins. A caliper defines a pair of bores which slidably 
receive the axially-extending pins so that the caliper is movably carried 
on the axially-extending pins. The caliper defines a pair of legs 
straddling the brake disc. A recess defined by the caliper between the 
pair of legs receives a pair of friction elements which interlock with the 
caliper. Each of the pair of friction elements carries a noise-reducing 
spring which engages the caliper to bias torque-transferring abutment 
surfaces of the friction elements and caliper into engagement with one 
another. 
Another sliding caliper disc brake is known in accordance with the U.S. 
Pat. No. 4,056,174 (hereinafter '174), issued Nov. 1, 1977 to H. Wienand 
et al, wherein a support member includes a pair of circumferentially 
spaced, axially extending arms which are radially spaced outwardly of the 
perimeter of the brake disc. The arms extend axially through the radial 
planes defined by the friction faces of the brake disc and define a recess 
therebetween. A pair of friction elements are received in the recess in 
torque-transferring abutting relation with the arms of the support member. 
The arms of the support member define a pair of axially extending bores 
therein. A caliper is received in the recess of the support member and 
carries a pair of axially extending pins which are slidably received in 
the bores of the support member. As a result, the caliper is slidably 
carried by the support member via the axially extending pins. The caliper 
defines a pair of legs which straddle the brake disc and the pair of 
friction elements. Each of the friction elements carries a spring which 
engages the caliper to urge the friction element radially inwardly within 
the recess of the support member. 
With a disc brake of the type illustrated by the '751 patent, all of the 
braking torque is transferred from the friction elements to the caliper 
during a brake application. The caliper transfers the braking torque to 
the support member via the axially extending pins. Because the friction 
elements are offset axially relative to the pair of pins, the caliper may 
pivot relative to the brake disc and support member. The caliper may pivot 
in an axially extending plane which is defined by the axes of the pair of 
pins. As a result, the caliper may not slide freely on the pair of pins 
during a brake application. Further as is well known in the art, reaction 
forces on the caliper during a brake application distort the caliper so 
that the caliper legs are spread apart or forced to move axially away from 
each other. As a result, the caliper legs are angulated relative to each 
other. Because the caliper legs oppose the friction elements, angulation 
of the caliper legs causes angulation of the friction elements and 
resultant uneven wear. Additionally, because the friction elements engage 
a circumferentially extending segment of the brake disc, a portion of the 
friction elements is subject to friction forces having a radially 
outwardly directed component. The outwardly directed friction forces are 
transferred to the caliper. As a result, the caliper may tilt radially 
outwardly. The caliper may tilt in an axially extending radial plane 
extending between the pair of pins. In the case of the outboard friction 
element which is on the side of the brake disc opposite the pair of pins, 
the tilting of the caliper adds to the angulation of the caliper leg 
caused by distortion of the caliper so that uneven wear of the outboard 
friction element is exacerbated. 
With a disc brake of the type illustrated by the '174 patent, the friction 
elements cooperate with the support member so that braking torque is 
transferred directly to the support member during a brake application. 
However, the reaction forces distort the caliper, as was explained supra, 
so that the caliper legs are angulated relative to one another. Further, 
the outwardly directed radial friction forces are transferred from the 
friction elements to the caliper because of the frictional engagement of 
the caliper legs with the friction elements during a brake application. 
Consequently, tilting of the caliper results and exacerbates the uneven 
wear of the outboard friction element. 
A further recognized deficiency of known sliding caliper disc brakes is the 
frictional drag of the friction elements, particularly, the outboard 
friction element, upon the brake disc when the brake is not applied. This 
unwanted frictional drag contributes to an increased fuel consumption for 
the vehicle upon which the brake is employed. 
Further, disc brakes according to both the '751 and '174 patents include a 
pair of axially-extending pins carried by the support member or caliper 
and a pair of bores defined by the caliper or support member for slidably 
receiving the axially-extending pins. Because the axially-extending pins 
and bores must precisely coincide with each other in order for the caliper 
to be axially movable relative to the support member and brake disc, 
precision manufacturing methods must be employed in order to make the disc 
brakes. Such precision manufacturing methods add to the expense of 
manufacturing the disc brakes. 
The invention as claimed is intended to avoid or ameliorate one or more of 
the shortcomings of prior disc brakes by providing a disc brake 
characterized by said pair of friction elements and one of said pair of 
arms defining cooperating abutment means for forming an interlocking fit 
therebetween, said interlocking fit substantially preventing radial 
movement of said pair of friction elements relative said one arm, said 
pair of friction elements and the other of said pair of arms defining 
coacting abutment means for substantially preventing radially inward 
movement of said pair of friction elements while allowing radially outward 
movement thereof, said pair of friction elements and said caliper defining 
associating abutment means for preventing radially outward movement of 
said pair of friction elements relative said caliper, resilient means 
extending between said caliper and said pair of friction elements for 
yieldably biasing said associating abutment means into engagement, said 
support member defining a single axially extending pin adjacent said other 
arm, said caliper defining an axially extending bore slidably receiving 
said single pin, and said single pin cooperating with said caliper to 
substantially prevent radially outward movement of said caliper and said 
pair of friction elements relative to said other arm. 
The advantages offered by the invention are mainly that the pair of 
friction elements cooperate with the support member to support the caliper 
so that only a single pin is needed connecting the caliper and support 
member. The pair of friction elements are interlocked with the caliper via 
a pair of axially extending resilient members so that the caliper and pair 
of friction elements may be assembled with and disassembled from the 
support member as a subassembly; which greatly simplifies assembly of the 
brake with a vehicle during manufacture and facilitates later maintenance. 
Because there is only a single pin connecting the caliper and support 
member, rather than the pair of pins of prior pin-slider, disc brakes, the 
manufacturing difficulties presented by the pair of spaced pins of prior 
brakes is avoided by the invention.

The figures show a disc brake 10 including a rotatable brake disc 12 having 
friction faces 14 and 16 on opposite sides thereof. The brake disc 12 is 
coupled by threaded fasteners 18 for rotation in unison with an axle 20 to 
be braked. A non-rotatable support member 22 is connected by threaded 
fasteners 24 to a torque-taking structure 26 which journals the axle 18. 
The support member 22 includes a pair of axially-extending arms 28 and 30 
which are circumferentially spaced to define a recess 32 therebetween. The 
arms 28 and 30 are spaced radially outwardly from the perimeter of the 
brake disc 12 and extend axially through the radial planes defined by the 
friction faces 14 and 16 on the brake disc, viewing FIG. 3. The arm 28 
includes a projection 34 extending circumferentially into the recess 32 to 
define a pair of axially-extending abutment surfaces 36 and 38. The arm 30 
defines an axially-extending abutment surface 40 which extends 
substantially parallel to a radially extending axial plane through the 
center of the recess 32. 
A pair of friction elements 42 and 44 are movably received in the recess 32 
of the support member 22. The friction elements include friction linings 
46 and 48, respectively, which are engageable with the friction faces 14 
and 16 of the brake disc 12. The friction linings 46 and 48 are secured to 
backing plates 50 and 52. Each of the backing plates 50 and 52 defines 
abutment surfaces 54, 56, and 58 slidably engaging the respective abutment 
surfaces 36, 38, and 40, of the arms 28 and 30 so that the support member 
22 may receive braking torque from the friction elements 42 and 44. 
Of course, the circumferential dimension of the backing plates 50 and 52 as 
defined by the surfaces 54-58 is slightly less than that of the recess 32 
as defined by the surfaces 36-40. As a result, a small clearance (not 
illustrated) may exist among the abutment surfaces. Because of the small 
clearance, the friction elements may be pivoted clockwise out of the 
recess 32 and removed radially outwardly from the support member 22. 
Conversely, the friction elements may be inserted radially inwardly into 
the recess 32 by counterclockwise pivoting movement. 
A caliper 60 is movably received in the recess 32 of the support member 22. 
The caliper 60 includes a bridge portion 62 and a pair of radially 
inwardly extending legs 64 and 66, viewing FIG. 2. The leg 66 of caliper 
60 defines a bore 68 movably receiving a piston 70 which cooperates with a 
closed end 72 of the bore 68 to define a variable-volume chamber 74. A 
groove 76 circumscribes the bore 68 and receives an annular sealing member 
78 cooperating with the piston 70. The leg 64 and the piston 70 are 
engageable with the friction elements 42 and 44, respectively. 
The caliper 60 includes radially and axially extending abutment surfaces 80 
and 82. Projections 84 and 86 on the backing plates 50 and 52 of each 
friction element 42 and 44 extend radially outwardly and define abutment 
surfaces 88 and 90, respectively, slidably engaging the abutment surfaces 
80 and 82 of the caliper 60. Of course, the friction element 42 is trapped 
between the caliper leg 64 and the brake disc 12 so that there is normally 
no relative sliding movement between the caliper and the friction element 
42. The projections 84 and 86 define slots 92 and 94 opening toward the 
center of the recess 32. The legs 64 and 66 of the caliper 60 define pairs 
of axially-spaced, circumferentially-extending projections 96, 98, and 
100, 102 aligning at their upper surfaces with the slots 92 and 94. A pair 
of axially-extending resilient members or wire-forms 104 and 106 extend 
through the slots 92 and 94 of the backing plate projections 84 and 86 and 
engage the projections 96-102 of the caliper. The resilient members 104 
and 106 are identical and have hook-shaped ends which engage the 
projections 96-102. Both of the resilient members 104 and 106 are 
torsionally distorted within the slots 92 and 94 so that the abutment 
surfaces 88 and 90 of the friction elements are resiliently biased into 
engagement with the abutment surfaces 80 and 82, respectively, of the 
caliper 60. 
Viewing FIGS. 1A, 6 and 6A, it will be seen with greater particularity that 
each of the resilient members 104, 106 include a center portion 136 and a 
pair of end portions 138, 140 which are offset relative to the center 
portion 136 and aligned with one another. The end portions 138 and 140 
have hook-shaped terminating portions 142 and 144, respectively, which 
engage the projections 96-102 of the caliper 60. The hook-shaped portions 
142 and 144 engage the underside (radially inwardly) of the projections 
96-102 while the end portions 138, 140 engage the upper side (radially 
outwardly) of the projections, as is best illustrated in FIG. 1A. The 
resilient members 104, 106 have a free or undistorted shape which is 
illustrated in FIGS. 6 and 6A and by dashed lines in FIG. 1A. When the 
center portions 136 of the resilient members 104, 106 are received in the 
slots 92, 94 of the friction elements, the resilient members 104, 106 are 
torsionally distorted and exert an upwardly directed (radially outwardly) 
force F on the friction elements 42, 44. 
The projections 86 at the left end of the friction elements 42 and 44 
define tab portions 87 which engage the arm 30 to restrain radially inward 
movement of the friction elements. Thus, it will be observed that the 
surfaces 36, 38 and 54, 56 at the right end of the friction elements 
interlock to restrain radial movement of the friction elements in both the 
inward and outward directions. At the left end of the friction elements, 
the tabs 87 restrain radially inward movement. Further, the caliper rests 
upon the friction elements via the surfaces 80, 82 and 88, 90 and is 
interlocked therewith via the resilient members 104 and 106. Thus, the 
support member 22 carries the friction elements 42, 44 which in turn carry 
the caliper 60. 
The support member 22 defines a bore 108, viewing FIG. 3, threadably 
receiving an axially-extending pin portion 110. Similarly, the caliper 60 
defines a bore 112 receiving an elongated bushing 114. The bushing 114 
defines a bore 116 slidably receiving the pin portion 110 so that the 
axially-extending pin portion 110 of the support member 22 also supports 
the caliper 60. Thus, the friction elements 42, 44 are trapped between the 
arm 30 and caliper 60. 
A pair of resilient members 118 and 120 are secured to the arms 28 and 30 
of the support member 22 by cap screws 122 which pass through apertures in 
the resilient members 120, 118 and engage threaded bores 124 in the arms 
28 and 30 viewing FIG. 5. The resilient members 118 and 120 are mirror 
images of each other and each includes a body portion 126 having a pair of 
axially-extending divergent arms 128 and 130. A pair of resilient arms 132 
and 134 extend axially toward each other from the arms 128 and 130, 
respectively. The arms 132 and 134 also are angulated and extend radially 
inwardly, viewing FIG. 4, to slidably and angularly engage the projections 
84 and 86 of the backing plates 50 and 52 of friction elements 42 and 44. 
The resilient arms 132 and 134 bias the friction elements radially 
inwardly. The engagement of the arms 132, 134 with the backing plates 50, 
52 is angular with respect to the backing plates and with respect to the 
rotational axis of the brake disc 12. Because of the angular engagement of 
the resilient arms 132 and 134 with the friction elements 42 and 44, the 
friction elements are also biased axially away from the brake disc 12. 
When a brake application is effected with the brake disc 12 rotating in a 
forward direction, which is indicated by arrow A, viewing FIG. 1, 
pressurized fluid is supplied to the variable-volume chamber 74, moving 
the piston 70 rightwardly, viewing FIG. 1. The piston 70 moves the 
friction element 44 into engagement with the friction face 16 on the brake 
disc 12. The pressurized fluid in the chamber 74 also acts on the closed 
end 72 of the bore 68 to move the caliper 60 leftwardly relative the brake 
disc 12 and support member 22, viewing FIG. 2. Consequently, the caliper 
60 moves the friction element 42 into engagement with the friction face 14 
on the brake disc 12. The caliper 60 is axially movable relative the 
support member 22 because the bushing 114 slidably receives the 
axially-extending pin portion 110 of support member 22, viewing FIG. 3, 
and because the abutment surfaces 80 and 82 of the caliper slidably engage 
the abutment surfaces 88 and 90 of the friction element 44 while the 
outboard friction element 42 slidably engages the support member 22 at the 
surfaces 34-38 and 54-58 and at tab 87. The inboard friction element 44 is 
axially movable, relative the support member 22, because the abutment 
surfaces 54, 56, and 58 of the backing plate 52 slidably engage the 
abutment surfaces 36, 38 and 40 on the support member. 
Viewing FIG. 1, braking torque generated by the frictional engagement of 
the friction elements 42 and 44 with the brake disc 12 is transferred from 
the friction elements to the support member 22 via the abutment surfaces 
40 and 58. Because the frictional engagement of the friction linings 46 
and 48 with the brake disc 12 extends circumferentially relative the brake 
disc, the friction elements are subject to a friction force which is 
directed radially outwardly, tending to pivot the friction elements 
counterclockwise, viewing FIG. 1. Because the friction elements define an 
interlocking fit with the support member at the projection 34 of the 
support member, the outwardly directed radial friction force is 
transferred to the support member 22 via the abutment surfaces 36 and 54. 
When a brake application is effected with the brake disc 12 rotating in the 
reverse direction, opposite arrow A viewing FIG. 1, braking torque is 
transferred to the support member via the abutment surfaces 36, 38, 54, 
and 56. The outwardly directed radial friction force tends to pivot the 
friction elements clockwise, viewing FIG. 1. Because the friction elements 
do not define an interlocking fit with the support member 22 at the 
abutment surfaces 40 and 58, the outwardly directed friction force is 
transferred from the friction elements to the caliper 60 via the abutment 
surfaces 82 and 90. The caliper 60 transfers the outwardly directed 
friction force to the support member 22 via the axially-extending pin 110. 
When a brake application is terminated, the pressurized fluid is released 
from the chamber 74. Consequently, the sealing member 78 retracts the 
piston 70 to a nonbraking position, as is well known in the art. The 
axially directed bias applied to the friction elements by the arms 132 and 
134 of the resilient members 118 and 120 moves the friction elements away 
from the friction faces 14 and 16 of the brake disc 12 so that the 
friction elements do not drag on the brake disc. 
Those skilled in the art to which the invention pertains will recognize 
that sufficent clearance exists between the friction elements and support 
member to allow the friction elements and caliper 60 to be pivoted 
clockwise as a unit out of recess 32, viewing FIG. 1, after the pin 110 
and resilient members 120 and 118 are removed. The resilient members 104 
and 106 retain the caliper and friction elements together so that the 
caliper 60 may be removed from and installed into the recess 32 of the 
support member 22 as a unit with the friction elements. In order to 
separate the friction elements from the caliper after the caliper and 
friction elements have been removed from the recess 32, the friction 
elements are pivoted away from the caliper at one of their ends (radially 
inwardly viewing FIG. 1) so that one of the resilient members 104 or 106 
snaps out of its slot 92 or 94. The friction elements will then slide off 
the other of the resilient members. Reassembly of the brake requires only 
the reversal of the above-outlined procedure.