Spring entrapment of split wedge floatation device

A disc brake assembly (10) includes a caliper (22) movably supported by a torque member (36). The caliper (22) and torque member (36) each have lateral recesses (44, 46, 48, 50) defining axially extending apertures (52, 54) between the caliper (22) and torque member (36), with a pair of wedge-shaped members (66, 68) disposed in each aperture to maintain the caliper in radial and circumferential position relative to the torque member while allowing lateral movement therebetween. The wedge-shaped members (66, 68) are biased inwardly by an improved dual purpose spring member (72) which traverses a portion of the exterior perimeter of the torque member (36) and engages the ends of the respective pins. The spring member (72) includes enlarged end members (74) each comprising a coil presenting a flat surface (75) for engaging the end of the respective pin (66, 68) to urge the pin inwardly of the aperture (52, 54), the enlarged end members (74) being disposed within the openings (90) of the apertures so that the enlarged end members (74) maintain the radial and circumferential position of the caliper (22) relative to the torque member (36) if the wedge-shaped pins (66, 68) are damaged or should fail.

The invention relates to a floating caliper disc brake. 
Floating caliper disc brakes include a rotor having friction faces on 
opposite sides thereof and a caliper cooperating with a pair of friction 
elements to urge the pair of friction elements into engagement with the 
friction faces to retard rotation of the rotor during brake application. A 
non-rotating torque member carries the caliper in substantially fixed 
radial and circumferential position relative to the rotor. The caliper is 
movable, or floats, axially to a limited extent relative to the rotor and 
torque member. 
A brake application is effected by a fluid motor carried by the caliper. 
When the fluid motor is supplied with a pressurized fluid, it forces one 
of the friction elements against a friction face of the brake disc. 
Reaction forces acting through the caliper cause the caliper to slide 
axially relative to the torque member and rotor so that the other friction 
element is forced against the other friction face of the disc brake. 
The floating caliper and torque member are coupled together to allow for 
axial movement of the caliper relative to the fixed torque member. 
Burnette U.S. Pat. No. 4,084,665 entitled "DISC BRAKE AND MOUNTING MEANS 
THEREFOR" and issued April 18, 1978, illustrates such a disc brake 
assembly and a means for floatably mounting the caliper to the fixed 
torque member. The caliper is supported by the torque member through pins 
having an elastomeric ring construction. Ritsema U.S. Pat. No. 4,318,458 
entitled "DISC BRAKE AND CONNECTING ASSEMBLY THEREFOR" and issued Mar. 9, 
1983, illustrates another construction having pins for slidably coupling 
together the caliper and fixed torque member. Both cited patents utilize a 
screw attached to the torque member and acting in conjunction with either 
a pin tab or a washer to retain a pin within the grooved recess between 
the caliper and torque member. U.S. Pat. No. 4,418,798 entitled "DISC 
BRAKE WITH WEDGE PINS", inventor Donald D. Johannesen et al., issued Dec. 
6, 1983, discloses another construction for slidably coupling together the 
caliper and torque member, and is incorporated by reference herein. This 
patent describes the use of wedge-shaped pins which engage one another 
along respective inclined surfaces while disposed within an axially 
extending aperture or recess located between the caliper and torque 
member. The pins are urged inwardly by a resilient spring member engaging 
sockets within the respective ends of the pins, whereby the pins fill the 
axially extending recess so that the caliper and torque member are not in 
direct engagement. This eliminates frictional engagement between the 
caliper and torque member both during and after braking when the caliper 
assembly returns to its initial deactivated position. Thus, the 
confronting surfaces of the caliper and fixed torque member do not come 
into engagement and this eliminates any frictional resistance to the 
return of the caliper to its initial deactivated position. This assists, 
along with runout or wobble of the disc brake assembly, to reposition the 
caliper axially relative to the torque member, so that the friction 
elements do not drag on the rotating brake disc. It further increases the 
wear life of the friction elements, prevents a decrease in fuel 
consumption due to dragging of the brakes, and provides a more efficiently 
operable and reliable disc brake assembly. 
The present invention is an improved means for retaining the wedge-shaped 
pins in proper position within the axially extending aperture located 
between and defined by axially extending recesses of the torque member and 
caliper. Although the wedge-shaped pins provide an improved mounting of 
the caliper relative to the torque member, it is possible that the pins 
may be damaged or destroyod during the operational life of the disc brake 
assembly. Therefore, it is important to first maintain the pins in their 
proper position within the axially extending aperture during the 
operational life of the disc brake assembly, and to provide, in the event 
there is destruction or failure of the wedge-shaped pins, for the caliper 
to be maintained in radial and circumferential position relative to the 
torque member. If the pins should fail, the caliper could separate from 
the torque member and cause failure of the disc brake assembly. Therefore, 
it is an object of the present invention to maintain the caliper in proper 
radial and circumferential alignment relative to the torque member if the 
pins should fail to maintain that alignment. 
The present invention comprises a dual purpose resilient spring which 
engages the respective ends of the wedge-shaped pin members to resiliently 
urge the pin members inwardly so that they are maintained in proper 
position within the axially extending aperture and thereby maintain the 
radial and circumferential alignment of the caliper relative to the torque 
member. The dual purpose spring traverses an exterior portion of the 
torque member to engage an abutment of the torque member and thus be 
secured in position relative to the torque member. The spring includes 
enlarged end members each comprising a coil which presents a flat surface 
for engaging the end of the respective pin to urge the pin inwardly of the 
aperture, with the enlarged spring end members disposed within the axially 
extending aperture. Because the enlarged end members are disposed 
interiorly of the axially extending aperture, the enlarged end members 
will maintain the radial and circumferential alignment of the caliper 
relative to the torque member if the wedge-shaped pins are damaged or 
should fail. The enlarged end members may also comprise a plurality of 
coils that present not only a flat surface for maintaining the pins in 
position within the aperture, but which provide further resilient biasing 
force urging the pins inwardly and provide additional support for 
maintaining the alignment of the caliper relative to the torque member if 
the pins are damaged or should fail. 
The invention is described in detail below with reference to the drawings 
which illustrate the embodiments of the invention. 
FIG. 1 is a side elevational view of the disc brake made pursuant to the 
present invention; 
FIG. 2 is a cross-sectional view taken substantially along line 2--2 of 
FIG. 1; 
FIG. 3 is an exploded view of the disc brake assembly utilizing the present 
invention; 
FIG. 4 is a fragmentary cross-sectional view taken substantially along line 
4--4 of FIG. 1; 
FIG. 5 is a isometric view of the pair of wedge-shaped members comprising 
one pin; and 
FIG. 6 is an isometric view of an alternative embodiment of the present 
invention.

Referring to FIGS. 1 and 2, a disc brake indicated generally by reference 
number 10 includes a rotor 12 rotatable with a wheel assembly (not shown) 
and having a pair of opposed friction faces 14 and 16. A pair of friction 
elements 18, 20 are disposed adjacent friction faces 14 and 16, 
respectively. The friction elements 18 and 20 are urged into braking 
engagement with their corresponding friction faces 14 and 16 when a brake 
application is effected. A caliper 22 includes a fluid motor portion 24 
disposed adjacent the friction face 14, a bridge portion 26 that traverses 
the periphery of the rotor 12, and a radially inwardly extending reaction 
portion 28 which is disposed adjacent the face 16. The fluid motor portion 
24 includes a piston 30 slidably arranged in a bore 32 defined within 
caliper 22. When a brake application is effected, fluid is communicated to 
the variable-volume chamber 34 defined between the end of the piston and 
corresponding end of bore 32 to urge piston 30 toward the rotor 12. Piston 
30 urges friction element 18 into engagement with friction face 14 and 
reaction forces acting through the bridge portion 26 move the caliper 22 
to bias friction element 20 into engagement with friction face 16. When 
the brake is subsequently released, piston 30 returns to its brakerelease 
position. 
Turning to FIG. 1, caliper 22 is mounted for axial movement with respect to 
the rotor 12 by a torque member 36, which is secured to a non-rotating 
portion of the axle assembly (not shown). The torque member 36 includes a 
pair of circumferentially spaced arms 38, 40, that define a recess 42 
therebetween. The caliper 22 is received in the recess 42 between torque 
member arms 38 and 40. Viewing FIG. 1, it will be seen that the caliper 22 
is spaced from the torque member 38 by clearance "D". Likewise, the 
caliper is spaced from the arm 40 by a clearance "E". In FIGS. 3 and 4, it 
can be seen that the torque member arms 38 and 40 and the caliper 22 
include matching V-shaped recesses or grooves 44, 46, 48, and 50, 
respectively. Recesses 44 and 48, and recesses 46 and 50, when placed in 
registry with each other, define substantially square-shaped apertures 52 
and 54, respectively. Apertures 52 and 54 extend axially between the arms 
38 and 40 and caliper 22. 
A pair of pins 56 and 58 are received in the apertures 52 and 54, 
respectively. FIG. 5 illustrates the pin 58 which includes a pair of 
wedge-defining members 66 and 68. The wedge members 66 and 68 are 
identical and complementary to each other, each having a transverse 
dimension B (see FIG. 4), and each includes an inclined surface 76. The 
members 66 and 68 overlap each other within the aperture 54 so that the 
members cooperate to define a cross-section similar to the cross-section 
of pin 56. FIGS. 1 and 4 illustrate that the wedge members 66 and 68 
cooperate to space apart the caliper 22 and the torque arm member 40. As a 
result, caliper 22 and torque member 40 define clearance "E". 
Correspondingly, the wedge members of pin 56 cooperate to space apart 
caliper 22 and torque arm member 38 to define clearance "D". 
As illustrated in FIGS. 1, 3, and 4, a C-shaped spring 72 (a portion of 
which is illustrated by FIG. 4) includes enlarged end members 74 which are 
received in an axially extending aperture. Spring 72 biases members 66 and 
68 toward each other within apertures 52, 54. Consequently, wedge members 
66 and 68 cooperate with each other at their wedge surfaces 76 whereby the 
surfaces slide on each other so that the pins have a variable cross 
section which correspondingly spaces the caliper 22 from the respective 
torque arm member. The pins are expansible to eliminate radial and 
circumferential clearances from the disc brake assembly. Each expansible 
pin 56 and 58 biases the caliper toward the other expansible pin, and thus 
maintains the clearances "D" and "E" between the caliper 22 and the 
respective torque arms 38 and 40. Turning to FIG. 4, it should be noted 
that the wedge members 66 and 68 are individually removable from the 
aperture 54. Removal of enlarged end members 74 of spring 72 from 
engagement with the ends of members 66 and 68 allows the wedge members to 
be removed from the aperture 54. Consequently, the caliper 22 is removable 
from the recess 42. 
The wedge members 66 and 68 have equal surface areas in contact with the 
caliper 22 and with the torque arm member arm 40. The surface area of 
member 68 which is in contact with caliper 22 is equal to the surface area 
of member 66 in contact with the caliper. Similarly, the area of member 68 
in contact with torque arm member 40 is equal to the area of member 66 in 
contact with the arm member 40. As a result, axial movement of the caliper 
22 creates balanced axial friction forces on each of the members 66 and 
68. Because the forces on the component parts of pin 58 (members 66 and 
68) are balanced, axial movement of the caliper 22 does not cause the pin 
58 to loosen or expand in aperture 54. Expansion of the pin 58 in aperture 
54 responsive to axial movement of the caliper could lock the caliper to 
the torque member, thereby preventing proper brake operation. 
The pins 56 and 58 are made of polyphenylene sulfide resin. This resin is 
inherently corrosion-resistant so that the sliding surfaces of the brake 
remain free of corrosion throughout the service life of the brake. The 
pins possess adequate mechanical strength when they are fabricated from 
polyphenylene sulfide resin reinforced with less than 30% to 40% weight of 
glass fibers. The pins 56 and 58 could also be made from metal, for 
example, stainless steel. 
As illustrated in FIGS. 1 and 4, the enlarged end members 74 of spring 72 
are disposed inwardly of the openings 90 of axially extending apertures 52 
and 54, each pin members 66, 68 being spaced apart from wall surfaces of 
aperture 90 to define longitudinal gaps therebetween, as illustrated 
clearly in FIG. 4. Each enlarged end member 74 presents a flat surface 75 
for engaging the flat end of the respective pin. The spring 72 biases the 
pins 66 and 68 inwardly of aperture 54, so that as pins 66 and 68 slide 
along their respective inclined surfaces, there is compensation for the 
manufacturing tolerances existing between the caliper and torque arm 
member. Each spring 72 also includes a portion 71 which engages a torque 
arm abutment 41 to maintain the exterior alignment of the spring 72 
relative to the torque arm. 
Each enlarged end member 74 is disposed within the associated axially 
extending aperture so that if the pins 66 and 68 should fail, either by 
damage imparted directly to the pins or failure of the material of the 
pins, then the end members 74 within the aperture will maintain the 
caliper in radial and circumferential alignment with torque arms 38 and 
40. This occurs because the enlarged end members 74 have a diameter large 
enough to substantially span the diameter of the aperture. Each end member 
74 is no larger than transverse dimension B of wedge members 66 and 68 so 
that members 66 and 68 normally maintain the position of the caliper, but 
if the members 66 and 68 should fail, end members 74 are large enough to 
maintain the position of the caliper. Thus, the enlarged end members 74 of 
spring 72 will maintain the caliper in radial and circumferential 
alignment with the torque member 36 and also permit axial movement of the 
caliper relative to the torque member. Maintenance of the caliper in 
proper radial and circumferential alignment with the torque member is an 
important safety device which enables braking operation until the disc 
brake assembly can be repaired by the insertion of new pins 66 and 68. 
Referring to FIG. 6, there is illustrated an alternative embodiment of the 
spring member which comprises a resilient spring 172 including enlarged 
end members 174. Enlarged end members 174 include multiple coils 176. 
Multiple coils 176 not only provide additional inward biasing of the pins 
66 and 68, but provide additional coils of the appropriate diameter for 
maintaining the caliper in alignment with the torque member if the pins 
are damaged or should fail. 
Although the present invention has been illustrated and described in 
connection with example embodiments, it will be understood that this is 
illustrative of the invention, and is by no means restrictive, thereof. It 
is reasonably to be expected that those skilled in the art can make 
numerous revisions and additions to the invention and it is intended that 
such revisions and additions will be included in the scope of the 
following claims as equivalents of the invention.