Caliper type disc brake

A caliper brake having a brake disc rotatable about an axis with a friction lining carrier mounted for sliding movement axially of the brake disc on a supporting caliper housing. The lining carrier has two circumferentially spaced ends with an opening at one end for receiving a torque pin mounted on the caliper housing for axial sliding movement of the carrier on the pin. A slot is provided at the other end for receiving a retention pin which is mounted on the caliper housing for axial sliding movement of the carrier on the retention pin. The retention pin is positioned in the slot with sufficient clearance to accommodate movement in the circumferential direction due to expansion and contraction of the carrier during braking. The clearance between the torque pin and the opening in the lining carrier is only sufficient to prevent binding of the carrier on the torque pin and therefore limits the movement of the lining carrier in a circumferential direction while providing a sliding connection for axial movement of the carrier into and out of braking engagement with the brake disc.

BACKGROUND OF THE INVENTION 
This invention relates to a caliper brake and especially to the connection 
of the lining carrier to the caliper housing. In a caliper brake at least 
one of the lining carriers is slidably mounted on the housing for movement 
of the carrier into braking engagement with the brake disc. This movement 
is in an axial direction relative to the brake disc, and clearance between 
the carrier and troque pins or thrust plate is necessary to permit 
movement. The amount of clearance is a function of the length of the 
lining carrier between the trogue pins or thrust plates and the 
temperature changes in the carrier during braking. In the past, lining 
carriers have been slidably supported on torque pins extending through 
semicircular cutouts at each end of the carriers. The distance between the 
cutouts is less than the distance between the torque pins to provide the 
necessary clearance for thermal expansion and contraction of the linging 
carriers. 
At normal braking temperatures, brakes with torque pins at both ends of the 
lining carrier have had up to .060 inches or more end-to-end movement with 
forward and reverse braking. This movement across the face of the 
actuating pistons after the brake is actuated pulls the piston to one side 
or the other causing side loading and damage to the piston surface, 
cylinder bore and the piston seals. This problem may also be present with 
brake designs of the type shown in applicant's Pat No. 3,357,524 where 
lugs on the ends of the lining carriers slidably engage slots in end 
plates of the housing. In another brake construction, the slots or notches 
are at both ends of the lining carrier and torque pins or lugs on the 
caliper housing fit in the slots or notches to transmit the torque. In all 
cases, the clearance must be sufficient to prevent binding of the lining 
carrier on the pins or lugs; however, this clearance has also caused the 
damage to the piston surface, cylinder bore and piston seals with lining 
carriers of normal length. Shortening the lining carrier will reduce the 
amount of expansion during braking but this in not a practical solution 
because of the cost of additional lining carriers and actuating mechanism. 
SUMMARY OF THE INVENTION 
The caliper brake of the present invention provides the necessary sliding 
clearance for elongation and contraction of the lining carrier while at 
the same time the circumferential movement of the lining carrier is 
limited to reduce or eliminate the damage to the actuating piston surface, 
cylinder bore and piston seals. One end of the lining carrier is slidably 
mounted on a torque pin with an opening of minimal clearance to take care 
of the relative expansion and contraction of the torque pin and 
manufacturing tolerances but no clearance for expansion and contraction of 
the lining carrier. The other end of the lining carrier has a slot for 
slidably receiving a retention pin in a position spaced from the ends of 
the slot. The retention pin is mounted on the housing and extends through 
the slot at a position spaced from the ends of the slot a distance at 
least as great as the total clearance needed for expansion and contraction 
of the lining carrier. No torque is transmitted through the retention pin 
and sufficient clearance is provided to prevent binding in the event the 
lining carrier is distorted or warped under the heat generated by the 
braking. With this construction, the circumferential movement of the 
lining carrier is limited because of the close clearance of the torque pin 
in the lining carrier opening. The lining carrier movement is limited to 
the clearance between the hole diameter and the pin diameter. The 
pin-to-hole clearance is limited by manufacturing tolerances and the 
clearance needed to prevent binding of the carrier on the pin in the event 
of tapered lining wear. In a comparable brake of the construction used 
heretofore, the reduction of circumferential lining movement with the 
design described herein may be from 500 to 1000 percent. Accordingly, the 
possibility of damage to the piston surface, cylinder bore and piston seal 
is greatly reduced. The construction of this invention is also less costly 
because it reduces the number of torque pins required and less material is 
required for the torque plate since the torque is only taken out at one 
end of the lining carrier. Also with the slotted construction, the lining 
carrier may be removed and replaced simply by removing the torgue pin and 
rotating the carrier out of the brake. 
The accompanying drawings show one preferred form of caliper brake made in 
accordance with and embodying this invention and which is representative 
of how this invention is practiced.

DETAILED DESCRIPTION 
Referring to FIGS. 1, 2 and 3, caliper brake assembly 10 is shown mounted 
on an axle housing 11. A wheel 12 having a flange 13 may be rotatably 
mounted on the axle housing 11 about an axis A--A of the axle and axle 
housing. A brake disc 14 is fastened to a cast mounting ring 15 on the 
flange 13 by cap screws 16 extending through the brake disc and into 
threaded engagement with threaded holes in the mounting ring at 
circumferentially spaced-apart positions around the flange. 
The axle housing 11 has a radially extending supporting flange 17 on which 
the caliper brake assembly 10 may be mounted. A supporting body or caliper 
housing 18 has a mounting flange 19 which fastens to the flange 17 of the 
axle housing 11 by cap screws 22 extending through holes 23 in the 
mounting flange 19 and in threaded engagement with threaded holes in the 
flange 17 at circumferentially spaced-apart positions. The mounting flange 
19 may be part of an inboard side 24 of the housing 18 which has an 
outboard side 25 and an outer body piece 26 connecting the inboard side 
and outboard side. The outer body piece 26 is disposed transversely of the 
barke disc 14 and the integral inboard side 24 and outboard side 25 flank 
the opposite sides of the disc and cooperate to maintain the brake 
actuating mechanism consisting of a group of piston-cylinder assemblies 
27. 
On each inboard side 24 and outboard side 25 of the housing 18, 
piston-cylinder assemblies 27 are mounted. The internal details of two of 
these piston-cylinder assemblies 27 are best shown in FIG. 2. The 
assemblies 27 have cylinder bores 28 in the housing inboard side 24 and 
outboard side 25 and sealing rings 29 in the bores provide fluid seals 
between pistons 32 slidably positioned in the cylinder bores. Each of the 
piston-cylinder assemblies 27 further includes annular flexible rubber 
boots 33 between the pistons 32 and the housing 18 to protect the sliding 
external surfaces of the pistons from damage by dirt, corrosion, etc. 
Fluid passages 34 are provided in the outer body piece 26 of the housing 
18 leading from a bleeder valve 35 for each pair of piston-cylinder 
assemblies 27 to the cylinder bores 28 of the respective piston-cylinder 
assemblies. One of the bleeder valves 35 is connected by suitable piping 
or flexible hose to a source of fluid pressure (not shown) for hydraulic 
actuation of the brake mechanism through communication of a brake fluid in 
any appropriate way to the passages 34 in the housing 18. An access plate 
36 is fastened by cap screws 37 to the face of the inboard side 24 of the 
housing 18 and retain cylinder head plates 38 in the cylinder bores 28 at 
the inboard side 24. 
Referring again to FIGS. 1 and 3, the caliper housing 18 has a first end 39 
shown at the left in FIG. 1 and a second end 42 shown to the right in FIG. 
1 with arcuate friction lining carriers 43 and 44 extending 
circumferentially of the brake disc from the first end to the second end 
of the housing. Friction linings 45 and 46 which may be either of an 
organic or metallic type abrasive lining material well known in the art 
are fastened to the lining carriers 43 and 44, respectively, by suitable 
adhesives or other forms of fasteners (not shown). As shown in FIG. 4, the 
friction lining 45 may be in three segments at circumferentially spaced 
positions along the friction lining carrier 43. 
At the second end 42 of the housing 18, torque thrust pins 47 extend 
through a hole 48 in the inboard side 24 and a hole in the outboard side 
25 (not shown). The torque thrust pins 47 are held in place in the holes 
by set screws 49 in threaded engagement with threaded holes in the side 
pieces 24 and 25 with the ends of the set screws engageable with the 
surface of the torque thrust pins as shown in FIG. 1. The torque thrust 
pins 47 extend into openings such as hole 52 in the friction lining 
carrier 43 at a second end 53 of the friction lining carrier 43, 
corresponding to the second end 42 of the housing, as shown in FIG. 4. 
Preferably the torque thrust pins 47 are cylindrical and fit in the holes 
of friction lining carriers 43 and 44 with a minimum diametral clearance 
to meet the design criteria and the available production tolerance 
capability. Thus minimum clearance is provided for sliding of the friction 
lining carriers toward or away from the brake disc 14 during operation of 
the brake. 
At the other or first end 54 of the lining carrier 43, a slot 55 with a 
centerline extending in a direction toward the torque pin hole 52 is 
provided at an outer edge 56. The edges of the slot 55 are in sliding 
engagement with a retention pin 57 extending axially of the brake disc 14 
and fastened as by set screws or welding to the outboard side 25 of the 
caliper housing 18. The retention pin 57 may be located at a position 
spaced from the end of the slot 55 a distance "d" which may be around 
0.060 inches or large enough to accommodate linear thermal expansion of 
the carrier, and the pin has a clearance of around 0.010 inches at the 
upper and lower sides of the slot. The slot 55 is open at the outer edge 
56 so that the friction lining carrier 43 may be removed for replacement 
simply by removing the torque thrust pins 47 and withdrawing the lining 
carrier from between the brake disc 14 and the adjoining outboard side 25 
of the caliper housing by moving them in a direction parallel to the 
braking surface of the braking disc. The friction lining carrier 44 has a 
similar construction to friction lining carrier 43 with a slot 58 slidably 
mounted on a retention pin 59 on the inboard side 24. The friction lining 
carrier 44 may be removed in the same manner as lining carrier 43. During 
this process the friction lining carriers 43 and 44 are slid off the 
retention pins 57 and 59 at the first end 39 of the caliper housing 18. 
New friction lining carriers 43 and 44 are inserted according to the 
reverse procedure. 
In the above description, the friction lining carrier 43 has been described 
along with its relationship to one of the torque thrust pins 47 and the 
retention pin 57 for the outboard side 25 of the caliper housing 18 and it 
is understood that the friction lining carrier 44 has the same 
construction except that it is a mirror image for positioning on the other 
side of the brake disc 14 with one of the torque thrust pins 47 and 
retention pin 59 mounted on the inboard side 24 of the caliper housing. 
In operation, the brake assembly 10 is hydraulically actuated by a source 
of fluid pressure communicated to the passages 34 and transmitted to the 
cylinder bores 28 urging the pistons 32 into engagement with the friction 
lining carriers 43 and 44 for compression of the friction linings 45 and 
46 against the moving surfaces of the rotatable brake disc 14. As the 
friction lining carriers 43 and 44 are urged against the brake disc 14, 
there is only limited circumferential movement of the friction lining 
carriers because of the relatively small clearance between the torque 
thrust pins 47 and the holes in the friction lining carriers. During 
braking, heat is generated and the friction lining carriers 43 and 44 will 
be elongated. This elongation will be accommodated by the clearance "d" 
between the retention pins 57, 59 and the ends of the slots 55, 58. Since 
the elongation and contraction of the friction lining carriers 43 and 44 
takes place at a relatively slow rate, the forces on the pistons 32 will 
not be sufficient to cause the side loading with resulting damage to the 
piston surfaces, cylinder bores 28 and piston sealing rings 29. At the 
same time, the slotted connection will accommodate an appreciable amount 
of warpage or twisting of the friction lining carriers 43 and 44 to 
provide unimpeded sliding of the lining carriers on the torque thrust pins 
47. 
The invention is capable of other modifications and adaptions by those 
having ordinary skill in the art and is more particularly defined by the 
appended claims.