EP1150850A1

EP1150850A1 - Trailing arm suspension with brake assembly mounting bracket

Info

Publication number: EP1150850A1
Application number: EP00904651A
Authority: EP
Inventors: Donald J. Hindman
Original assignee: Holland Neway International Inc
Current assignee: Holland Neway International Inc
Priority date: 1999-02-04
Filing date: 2000-02-02
Publication date: 2001-11-07
Also published as: MXPA01007859A; WO2000046052A8; AU2637700A; CA2360561A1; WO2000046052A1

Abstract

A trailing arm suspension comprising a pair of trailing arm assemblies (16) carrying an axle (12) on which ground-engaging wheels are mounted. Each of the trailing arm assemblies comprises a trailing arm (18) having one end pivotally mounted to a frame bracket (20) depending from a vehicle frame (10) and another end connected to the vehicle frame through an air spring (24) that resiliently resists the pivotal movement of the trailing arm. The axle is connected to the trailing arm between the pivotal connection and the air spring by a wrapper band (40) that compressively holds the axle and is coupled to the trailing arm by a resilient connection (26, 28). A brake assembly mounting bracket (70, 72, 74) is rigidly connected to at least one of the wrapper bands and couples the operating movement of the brake assembly with the axle.

Description

TRAILING ARM SUSPENSION WITH BRAKE ASSEMBLY MOUNTING BRACKET

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of the following provisional applications: Serial No. 60/163,525, filed November 4, 1999 and Serial No. 60/118,627, filed February 4, 1999.

BACKGROUND OF THE INVENTION Technical Field

This invention relates to vehicle suspension systems for mounting ground- engaging wheels to a vehicle frame, and, more particularly, to trailing arm suspensions having an axle assembly mounting brackets coupling the axle to each arm and a brake assembly mounting bracket coupling the brake system components to the axle assembly mounting brackets. Description of Related Art Trailing arm suspensions are well known and commonly used in heavy-duty vehicle applications, such as semi-tractor/trailer configurations. A typical trailing arm suspension comprises a pair of trailing arm assemblies mounted on opposite sides of the tractor or trailer (genetically referred to as the "vehicle") frame and carry between them an axle mounting ground engaging wheels. The trailing arm assemblies are usually identical and comprise a trailing arm pivotally mounted at one end to the vehicle frame, typically through a frame bracket, and resiliently connected to the vehicle frame along the arm, typically at another end, through an air spring for resiliently resisting pivotal movement of the trailing arm relative to the frame. The axle is mounted to the trailing arms between the pivotal connection to the frame bracket and the air spring or between the air spring the other end of the arm.

All trailing arm suspensions are susceptible to vehicle roll-induced bending moments, which can occur in response to the vehicle turning a corner or one of suspension assemblies changing elevation with respect to the other, such as running over a curb or dropping into a hole. Any of these situations results in a tendency of the vehicle to rotate or "roll" about the longitudinal axis of the frame and thereby unevenly distribute the forces on the trailing arm assemblies. This uneven distribution of forces on the trailing arm assemblies tends to result in a vertical bending moment on the axle if not absorbed or attenuated. The repeated application of the roll-induced bending moment on the axle causes cyclic loading of the axle and can contribute to axle failure.

In order to limit the bending moments on the axle due to vehicle roll, it is desirable to relieve or attenuate the roll-induced bending moments on the axle. Historically, the solution to relieving the roll-induced bending moments falls into two categories based on the type of trailing arm: a flexible trailing arm or a rigid trailing arm. A flexible trailing arm (a/k/a a spring beam) is made from one of more straps of spring steel that is capable of resiliently deflecting, much like a spring, to relieve the roll-induced bending moments. The flexible beam is advantageous in that since the beam flexes to relieve the vertical bending moments, the type of connection (resilient or rigid) between the flexible beam and the frame bracket and axle is unimportant under normal circumstances. The disadvantage of the flexible beams is that they are typically heavier than rigid beams and in some cases are expensive to manufacture.

Another approach to relieving the vertical bending moments focuses on a rigid beam that is typically made by welding multiple plate steel elements together, usually in a box-beam or I-beam configuration. The rigid beam is advantageous over the flexible beam in that it has substantially reduced weight and is much easier to form since only simple welding methods are required. The disadvantage of the rigid beam is that it cannot sufficiently bend or flex to relieve the roll-induced bending moments. Any roll-induced bending moments reaching the rigid beam are transferred to other suspension components, including the axle. The relief of the roll-induced bending moments must be addressed elsewhere in the suspension.

For most rigid beam suspensions, both of the beam-to-frame connection (typically, the pivotal connection at the frame bracket) and the axle-to-beam connection (typically, a bracket connecting the axle to the arms) are resilient to permit the beam to articulate with respect to the frame and the axle to articulate with respect to the beam, respectively, to relieve the roll-induced vertical bending moments. The resilient connection is usually accomplished by using a bushed connector as disclosed, for example, in U.S. Patents 3,332,701; 3,140,880; 3,482,854 and 3,547,215.

It has been common practice to weld axles directly to the trailing arm or to brackets that are resiliently mounted to the trailing arms. Other components, such as radius rod towers and brake components are typically welded to the axle. Any weld on the axle tends to form areas of weakness where cracks form with repeated torsion or vertical loading. The likelihood of cracks initiating at the welds is increased if the axle is susceptible to the roll-induced vertical bending moments.

There have been many attempts to weld an axle directly to the beam or to an intervening axle bracket in a manner to reduce the welds on axle failures due to roll- induced vertical lifting moments on the welds. U.S. Patent No. 3,547,215 to Bird (issued December 15, 1970), discloses a trailing arm suspension wherein a square axle is typically welded to a bracket which is, in turn, secured to the trailing arm of the vehicle suspension structure. The weld securing the axle to the bracket is usually made at the mid-point of the side of the axle where roll-induced bending moment stresses are neutral. However, these areas are areas loading which results from brake torque, vehicle roll and diagonal axle (wheel) walk, increasing the likelihood of axle failure.

German Patent Nos. DE 42 32 779 and DE 42 32 778 disclose a vehicle suspension system with an air spring or a leaf spring wherein a relatively square axle is tied in to the suspension through a U-bolt and axle plate which bears against the axle at an upper portion. A filler can be provided in the bottom of the U-bolt. A ring received in an opening in the axle plate is welded to an upper surface of the axle. Frictional force resulting from pressure applied by the axle plate at the upper corners of the axle and by the filler plate at the bottom corners of the axle coupled with the welded ring is said to hold the axle against movement in the mounting. A U-bolt does not give consistent and sufficient compressive forces to adequately prevent slippage of an axle in the mounting and does not work well with round axles.

A solution to the weld problem is disclosed in U.S. Patent No. 4,693,486 to Pierce et al. (issued September 15, 1987), which discloses a trailing arm suspension in which an axle secured to a trailing arm by a wrapper plate partially surrounding the axle, a bolt compresses the wrapper plate about the axle so that the wrapper plate supports and strengthens the axle, and a circular plug weld is positioned on the axle in a circular opening in the wrapper plate to attach the wrapper plate to the axle. Although this system is a significant improvement over the previous welds to the axle, the plug weld still may be a source of stress cracks in the axle.

It is also common to mount a track bar between a trailing arm and a central portion of an axle. The track bar is mounted to the axle through a tower bracket which is welded to a central portion of the axle. The welds between the tower bracket and the axle can introduce in the axle weak points and microscopic cracks which can form sources of cracks which may ultimately result in failure of the axle under severe or prolonged loading conditions.

U.S. Patent No. 5J 16,075 to Pierce (issued May 26, 1992), discloses a trailing arm suspension wherein a wrapper plate is mounted to an axle through mechanical compression and desirably without welding to the axle. Adapter plates mounted to the ends of the plate apply a compressive force to the corners of a square axle when the wrapper plate is compressed against the axle by a bolt. The wrapper plate is mounted on a pair of side plates which in turn are fixed to the trailing arm. Although the suspension is potentially effective to reduce the potential of crack initiation of the axle between the axle and the axle bracket, a considerable amount of skilled labor is involved in assembling the axle to the trailing arm suspension, frequently at the point of assembly to the axle and suspension to the vehicle. The forces of compression tend to be somewhat uneven.

Traditionally, S-cam brake assemblies have been mounted to the axle, typically by welding to maintain the proper alignment of the brake assembly components. Welding inboard of the trailing arms can result in weld induced axle weaknesses that are susceptible to crack initiation as a result of cyclic loading as described above. It would be desirable to avoid welding the brake components to the axle to avoid unnecessary weld induced weaknesses in the axle. However, it is necessary to maintain absolute rigidity between at least the axle and the S-cam bearing and desirably between the brake actuator and the axle for proper operation of the brakes. Any relative movement between the axle and the S-cam bearing or between the axle and the brake actuator can adversely affect the operation of the brakes. Thus, mounting of the S-cam bearing and the brake actuator to the trailing arm or beam in a typical bushed joint connection between the beam and axle has not heretofore been possible. U.S. Patent No. 5,366,237 to Dilling et al., discloses a trailing arm suspension in which a round axle is mounted in openings in a pair of side plates in a rigid beam and welded to the side plates around the openings, resulting in a rigid axle-to-beam or arm connection. In one embodiment, a sleeve that extends the width of the rigid beam is mounted on the axle and is welded to the axle and side plates of the rigid beam. A special patented bushing must be used in the pivotal mounting between the rigid beam and the frame bracket to alleviate axle loading due to vehicle roll. A brake actuator and an S-cam bearing are mounted directly to the rigid beam for operating brakes on the axle wheels. The rigid mounting of the axle to the rigid beam unitizes the rigid beam and axle so that the brake actuator and the S-cam bearing can be mounted directly to the rigid beam rather than to the axle. Although the Dilling et al. '237 suspension avoids the resilient coupling of the axle to the rigid beam, and therefore permits the direct mounting of the brake components to the rigid beam, the suspension does not avoid weld induced stresses on the axle and is thus subject to failure at the welds due to cyclic loading. Further, the Dilling et al. suspension requires a special patented bushing between the rigid beam and the frame bracket. Further, the fracture of the axle results in scrapping of the entire rigid axle-beam subassembly because of the welding of the axle to the rigid beam.

A suspension system in which an axle is mounted to a trailing arm through a wrapper band which compresses the axle without welding is disclosed in PCT International Application Number PCT/US97/18733. In this application, the axle is mounted to sets of relatively narrow wrapper bands which are held in tension by compressing end portion of halves of the wrapper bands together and joining the halves together while the are compressed on the axle. Mounting of brake components to the wrapper bands and to axle brackets is also disclosed. SUMMARY OF THE INVENTION

The invention relates to a vehicle suspension for mounting ground-engaging wheels to a vehicle frame. The suspension system comprises a pair of trailing arm assemblies, each of which is adapted to be mounted to a different side of the vehicle frame and comprises an arm. At least one wheel-carrying axle is mounted to each of the arms through an axle mounting assembly. A brake assembly bracket is mounted to the axle mounting assembly and mounts a brake actuator and an S-cam bearing.

The axle mounting assembly can include at least one and preferably two hollow wrapper bands that rigidly connect the axle to one or more axle mounting plates which are in turn resiliently connected to one of the arms. Preferably, the brake assembly bracket is mounted to the wrapper band. The brake assembly bracket is preferably removably mounted to the wrapper band, typically through bolts. In one embodiment, at least one axle mounting plate is resiliently connected to one of the arms and rigidly mounted to at least one wrapper band. The hollow wrapper band or bands have a width greater than a thickness and circumscribes the axle with inner surface portions shaped to conform to at least a portion of at least two sets of diametrically opposed and circumferentially spaced external surfaces of the axle. The hollow wrapper band or bands are in tension sufficient to compress the axle at each of the inner surface portions of the wrapper band and evenly distribute a compressive load on the axle across the at least two sets of diametrically opposed external surfaces of the axle sufficient to prevent relative movement of the axle with respect to the wrapper band under ordinary service conditions. In one embodiment, each of the brake assembly brackets is rigidly connected to two wrapper bands. The brake assembly bracket preferably comprises a coupling portion mounting the brake assembly bracket to the axle mounting assembly, a brake actuator mounting portion to which the brake actuator is mounted, and an S-cam bearing mounting portion to which the S-cam bearing is mounted. In one embodiment, the coupling portion is a plate, generally transverse to the axle, with an arcuate upper edge partially circumscribing the axle. In another embodiment, the coupling portion is preferably connected to the arm through at least one, and preferably two, bushed connectors. The bushed connectors comprise an inner sleeve, an outer sleeve, and an elastomeric annulus disposed between the inner and outer sleeves. The outer sleeve is rigidly connected to the arm, and the inner sleeve is rigidly connected to the axle mounting bracket and to the brake assembly bracket. The brake assembly bracket is preferably mounted to at least one wrapper band. Preferably, the brake actuator mounting portion includes a front plate extending transversely from one of the side plate and an S-cam bearing mount is mounted on the side plate near another end of the side plate. Typically, the brake actuator is mounted near a first end of the brake assembly bracket, and the S-cam bearing is mounted near the second end thereof.

In one embodiment, at least one wrapper band has multiple ears, each ear having an opening, and the arcuate plate has corresponding openings formed along the inner edge. Fasteners, for example, bolts, pass through the ear openings and inner edge openings to mount the brake assembly bracket to the wrapper band. In one embodiment, the brake actuator mounting portion extends laterally from an end of coupling portion and the S-cam bearing portion is substantially coplanar with the coupling portion.

In one embodiment, the arms are mounted generally above the axle and the brake assembly brackets are mounted generally below the axle. In another embodiment, the arms are mounted generally below the axle and the brake assembly brackets are mounted generally below the axle.

The trailing arm suspension according to the invention effectively controls or relieves the roll-induced vertical bending moments and eliminates stress concentration areas on the axle that are susceptible to crack initiation in response to the roll-induced vertical bending moments. Additionally, it also provides for a removable mounting of the brake actuator and S-cam brake assembly components to the axle mounting assemblies and thus avoids a separate mounting of these components directly to the axle or to the trailing arm beam.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in detail with reference to the accompanying drawings in which: FIG. 1 is a side elevational view of a suspension system according to a first embodiment of the invention, illustrating the mounting of a brake actuator to the axle mounting assembly according to the invention;

FIG. 2 is a perspective view of the axle mounting assembly and brake actuator bracket illustrated in FIG. 1 ;

FIG. 3 is a perspective view similar to FIG. 2 and including components of the brake assembly;

FIG. 4 is a side elevational view of a second embodiment of a suspension system according to the invention comprising an overslung suspension with a resilient axle-to-beam connection and an S-cam brake assembly mounted to the resilient axle- to-beam connection through a brake actuator mounting bracket;

FIG. 5 is an enlarged lower perspective view of a portion of the second embodiment suspension illustrated in FIG. 4 as seen from the outside of the vehicle;

FIG. 6 is an enlarged lower perspective view of a portion of the second embodiment suspension illustrated in FIG. 4 as seen from the inside of the vehicle;

FIG. 7 is a perspective view of the brake assembly mounting bracket and wrapper bands of the suspension system illustrated in FIG. 4;

FIG. 8 is a left-rear perspective view of a third embodiment of a suspension system according to the invention comprising an underslung suspension with a resilient axle-to-beam connection and an S-cam brake assembly mounted to a brake assembly mounting bracket;

FIG. 9 is a left-bottom perspective view of the suspension of FIG. 8;

FIG. 10 is a partial sectional view taken along line 10-10 of FIG. 8;

FIG. 11 is a left-bottom view of a fourth embodiment of a suspension system according to the invention comprising an underslung suspension with a resilient axle- to-beam connection and an S-cam brake assembly mounted to a brake actuator mounting bracket; and

FIG. 12 is a partial sectional view taken along line 12-12 of FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1-3 illustrate a trailing arm suspension 14 comprising a trailing arm assembly 16 mounted to vehicle frame 10 and carrying an axle 12, supporting ground-engaging wheels (not shown) in a traditional manner. There are two trailing arm assemblies, each mounted on opposing sides of the vehicle frame. For convenience, only one of the trailing arm assemblies 16 will be described with the understanding that the description applies to both. The front of the vehicle is to the left of the frame as viewed in FIG. 1. The trailing arm assembly 16 includes a trailing arm 18 pivotally mounted to a hanger bracket 20 depending from the frame 10. The hanger bracket 20 has a pivot pin 22, preferably in the form of a bushed connector, at the lower end thereof for pivotally supporting the forward end of trailing arm 18. Trailing arm 18 is preferably a rigid beam comprising a hollow rectangular construction.

The trailing arm 18 extends rearward along the vehicle frame 10. The rear end of the trailing arm 18 is secured to an air spring 24, whose upper end is fixedly mounted to the vehicle frame 10. Trailing arm 18 is known as an "overslung" trailing arm in that the axle 12 is carried beneath the trailing arm 18. To accommodate the axle 12, the over-slung arm has a slight downward bend intermediate between its forward and rear ends.

A forward bushed connector 26 and a rear bushed connector 28 extend through trailing arm 18 near the slight downward bend therein for supporting an axle mounting assembly 30 while permitting limited articulation between the axle mounting assembly 30 and the trailing arm 18. The upper portion of the air spring 24 is fixedly secured to the vehicle frame 10.

The axle mounting assembly 30 comprises a pair of mounting plates 32, each having openings 34 for receiving a portion of the bushed connectors 26, 28 to resiliently secure the mounting plates to the arm 18. An S-Cam bearing mount or seat 36 is integrally formed with at least one of the mounting plates 32.

The axle mounting assembly further comprises a pair of wrapper bands 40, each mounted to one of the mounting plates 32. Each of the wrapper bands 40 comprises an upper U-shaped plate 42 fixedly connected to mounting plate 32, preferably by welding at 44, and a lower U-shaped plate 46. The welds 44 appear on both sides of the mounting plates. The upper U-shaped plate 42 extends laterally from each side of the mounting plate 32 to provide a semicircular surface 45 to bear against the outer surface of the round axle 12. The lower U-shaped plate also has a semicircular surface 47 that bears against the axle 12. The upper and lower U-shaped plates are welded together at their corresponding ends 48, 50, respectively, through welds 52. The upper U-shaped plate 42 has a chamfered relief area 52 near each longitudinal edge which provides a slight relief to the axle at the lateral edges of the upper U-shaped plate 42. In a similar manner, the lower U-shaped plate 46 has a chamfered relief area 54 at the lateral edges thereof. The chamfered relief areas 52, 54 effectively circumscribe the axle 12. These chamfered areas prevent stress risers in the axle 12 which may result from the lateral edges of the U-shaped plates 42, 46 during vertical bending of the axle. The chamfered areas are desirable in some instances but they are not essential.

The upper and lower U-shaped plates 42, 46, respectively, are mounted to the axle and their corresponding ends 48, 50 secured in such a manner that the U-shaped plates apply a compressive force to the axle 12 to hold it in place without directly welding the plates 42, 46 to the axle 12. Preferably, the plates 42, 46 are tensioned so that they apply the compressive force to the axle 12. The tension method is known and described in greater detail in U.S. Patent Application No. 09/134,856, which is incorporated by reference. With this configuration, the wrapper band compresses the axle and distributes the compressive forces substantially uniformly around the axle. The compressive force is sufficient to prevent the wrapper band from sliding on the axle.

A brake actuator bracket 70 is mounted to each of the lower U-shaped plates 46. The brake actuator bracket 70 comprises a pair of triangular side plates 72 and a rectangular end plate 74. A central opening 76 and a pair of bolt openings 78 are formed in the rectangular end plate 74. A brake actuator chamber 80 is mounted to the brake actuator chamber bracket 70 through bolts (not shown) which extend through the bolt openings 78 in the rectangular end plate 74. An actuator rod 82 extends from the brake actuator chamber and is connected to a clevis 84 which in turn mounts a slack adjuster 86. An S-cam shaft 90 is rigidly connected to and is rotatably driven by the slack adjuster 86. The S-cam shaft mounts an S-cam 92 and is journaled in an S-cam bearing 94. The S-cam bearing 94 is mounted to the S-cam bearing mount 34 through bolts 96 which extend through bolt openings 98 in the mounting plate 32. The brake assembly comprising the brake chamber 80, the actuator rod 82, the clevis 84, the slack adjuster 86, the S-cam shaft 90, the S-cam 92, and the S-cam bearing 94 are all conventional and operate a brake on a wheel in conventional fashion.

In operation, vertical movement of the ground-engaging wheels 14 is translated through axle 12 to the axle mounting assembly 30. Vertical movement of axle mounting assembly 30 is translated to trailing arm 18 through forward bushed connector 26 and rear bushed connector 28. The articulation permitted between axle mounting assembly 30 and trailing arm 18 by the bushing of forward bushed connector 26 and rear bushed connector 28 cushions the vertical movement of the trailing arm 18 and relieves or attenuates the magnitude roll-induced lifting moments transferred to the axle 12 from the arm 18.

Significant vertical displacement of axle mounting assembly 30 causes the vertical displacement of trailing arm 18. Vertical movement of trailing arm 18 is permitted by the pivotal connection of the forward end of trailing arm 18 at the pivot pin 22. The vertical movement of trailing arm 18 is cushioned and restrained by air spring 24 and a shock absorber 60.

FIGS. 4-7 illustrate a second embodiment of the invention where the entire brake assembly is mounted to the axle mounting assembly through a brake assembly mounting bracket, instead of an actuator bracket and the axle mounting plates as in the first embodiment. Since the first and second embodiments share many similar components, like numerals have been used to designate like parts.

The axle mounting assembly 130 of the second embodiment comprises a pair of bracket or mounting plates 132 mounted to the trailing arm through bushed connectors 26 and 28. An upper U-shaped wrapper plate 142 is integral with the mounting plate 132. As best seen in FIG. 7, the upper U-shaped plate 142 extends laterally from each side of the mounting plate 132 to provide a semicircular surface 145 to bear against the outer surface of the round axle 12. A lower U-shaped plate

146 having upper edges 50 has a semi-cylindrical inner surface 154 which bears against the outer surface of the axle 12. The upper and lower U-shaped plates 142 and 146 are joined through a weld 150 after being pressed together to apply compression to the axle 12. The lower U-shaped plates 146 have a pair of ears 147, each with a through hole 149. The axle 12 mounts a spindle 100 that in turn mounts a brake mounting plate 102 in conventional fashion.

A brake assembly mounting bracket 170 is mounted to each of the lower U- shaped plates 146. The brake assembly mounting bracket 170 comprises a side plate 171, a front plate 174, and a side flange 172. The front plate 174 has a central hole 176 and four mounting holes 178 arranged in a square pattern around the central hole 176. The side plate 171 has a pair of openings (not shown) through which extend bolts 179. The bolts 179 extend through the openings 149 in the ears 147 to mount the side plate 171 to one of the lower U-shaped plates 146. The side flange 172 has at an upper portion an opening (not shown) through which extends a bolt 179 which also extends through an opening 149 in an ear 147 on the other lower U-shaped plate 146 to mount the mounting bracket 170 thereto. The side plate 171 further has an opening 197 and four mounting holes 198 space about the opening 197. A bearing bracket 200 formed of a plate 202 having four mounting holes 204, a bearing 206 with a central opening 208 and an arcuate slot 210 are mounted to the side plate 171 through bolts 179 which extend through the mounting holes 204 and corresponding holes in the mounting holes in the side plate 171 in a conventional fashion. The bearing 206 projects through the opening 197 in the side plate 171.

A brake actuator chamber 80 is mounted to the brake actuator chamber bracket 170 through bolts (not shown) which extend through the bolt openings 178 in the rectangular front plate 174 in conventional fashion. An actuator rod 82 extends from the brake actuator chamber and is connected to a slack adjuster 84 through a clevis mounting 85. An S-cam shaft 90 is rigidly connected to and is rotatably driven by the slack adjuster 84. The S-cam shaft 90 mounts an S-cam 92 and is journaled in the S- cam bearing assembly 200 comprising a plate 202, which is connected to the mounting plate 102 in conventional fashion. The S-cam bearing plate 202 is mounted to the bearing bracket 200 through bolts 212 which extend through bolt openings 204 in the bearing mounting plate 200 and through corresponding bolt openings in the side plate 171. An S-cam bearing 206 is journaled to the S-cam bearing plate 202. The S-cam shaft extends through the central opening 208 in the bearing bracket 200 and S-cam bearing 206.

The arcuate slot 210 provides an initial adjustment of the slack adjuster 84 with respect to the S-cam shaft 90. The mounting holes 204 are in registry with holes 198 in the side plate 171. An adjuster plate 214 is non-rotatably mounted to the slack adjuster 84 and has a flange 216 that extends laterally and then upwardly. The upper portion of the flange 216 has an elongated slot 218 which is connected through a pin (not shown) to the arcuate slot 210 in conventional fashion to initially set the position of the slack adjuster shaft with respect to the S-cam shaft 90 and to automatically adjust the slack in the connection between the S-cam and the actuator shaft 82 in a conventional fashion. The brake actuator and S-cam linkage is conventional and forms no part of this invention except to the extent that they are mounted to the brake actuator mounting bracket 170. The brake actuator comprising the brake chamber 80, the actuator rod 82, the clevis mounting 85, the slack adjuster 84, the S-cam shaft 90 and the S-cam 92 are all conventional and operate a brake on a wheel in conventional fashion. However, the mounting of the S-cam bearing and the brake chamber 80 to the axle mounting assembly avoids welding of brackets for mounting these components to an axle. It additionally prepositions the S-cam portion of the brake assembly with the brake actuator, ensuring their relative continued alignment, especially since they are both connected to the same bracket, which is only connected to the axle mounting assembly.

As illustrated in FIG 7, the mounting plate 132 mounts a U-shaped bracket 220 with holes 222 through welds 224. The shock absorber 60 is pivotally mounted to one of the mounting plates 132 through a pin (not shown) as is conventional in the suspension system art. FIGS. 8 - 10 illustrate a third embodiment of the trailing arm suspension according to the invention where like numbers have been used to designate like parts. The third embodiment suspension is an underslung suspension comprising a rigid trailing arm or beam 18 having one end pivotally mounted to a hanger bracket 20 by a bushed connector 22. The hanger bracket depends from a vehicle frame (not shown) in a well-known manner. An air spring 24 is positioned between a portion of the beam 18 and the frame rail. The air spring 24 dampens the pivotal movement of the trailing arm 18 relative to the hanger bracket.

An axle mounting assembly 130 resiliently mounts an axle 12 to the beam 18. The axle mounting assembly comprises a pair of mounting plates 132, which are resiliently connected to the rigid beam 18 by a pair of bushed connectors 26, 28. The mounting plates 132 include a compression mount comprising a first U-shaped wrapper plate 142, integrated with the mounting plates 132, and a complementary second U-shaped wrapper plate 146, which is welded to the first U-shaped wrapper plate 142. The axle 12 is compressively retained between the first and second U-shaped wrapper plates 142 and 146 to fixedly mount the axle 12 to the axle mounting assembly 130.

As illustrated in FIG. 12, the bushed connectors 26 and 28 are well known and comprise an outer sleeve 326 and an inner sleeve 328, between which is disposed an elastomeric annulus 340. The outer sleeve 326 is slightly shorter than the inner sleeve 328. The outer sleeve 326 is rigidly welded between the sides of the rigid beam 18 whose length is less than that of the inner sleeve 328 so relative movement between beam 18 and axle mounting assembly 130 may occur.

Washers 344 are positioned between the outer ends of the inner sleeve 328 and the mounting plates 132. The compression bolt 342 extends through the interior of the inner sleeve 328 and receives a nut 346, which upon the tightening of the nut 346, the bolt 342 compressively clamps the mounting plates 132 to the inner sleeve 328. The trailing arm suspension further comprises a brake assembly mounting bracket 370 that mounts a brake actuator assembly to the mounting plates 132. The brake actuator assembly is well known and generally comprises an air operated actuator 80 from which extends an actuator rod 82, which reciprocates relative to the actuator 80 upon the introduction and exhaustion of pressurized air at the brake actuator 80. An S-cam bearing 206 mounts a cam shaft 90 through a slack adjuster 86 and has an S-cam 92 on an outer end thereof. The rotation of the cam shaft 90 turns the S-cam 92 to actuate the brakes 344, which are mounted to the axle 12.

The brake assembly mounting bracket 370 comprises a longitudinal mounting plate 371 that parallels the rigid beam 18 and terminates at one end in a brake actuator mounting platform 374 and at the other end in a bearing retainer 383. The brake actuator platform 374 comprises mounting bolt openings and a pushrod opening that receive mounting bolts 375 and actuator rod 82 associated with the brake actuator 80. Nuts 377 are threaded onto the bolts 375 to fasten the brake actuator 80 to the brake actuator platform 374. The actuator rod 82 extends through the pushrod opening 376 when the brake actuator 80 is properly mounted to the longitudinal mounting plate 371. The bearing retainer 383 comprises an opening in which the S-cam bearing 206 is received and the S-cam bearing 206 is then affixed to the bearing retainer 383. Referring to FIGS. 9 and 10, the brake assembly mounting bracket 370 is rigidly connected to the axle mounting plates 132 by passing the bushed connector mounting bolts 342 through openings in the longitudinal mounting plate 371.

Cylindrical spacers 381 are positioned between the exterior of one of the mounting plates 132 and the longitudinal mounting plate 371 and slidably receive the mounting bolts 342. Upon the tightening of the nuts 346, the longitudinal mounting plate 371 is compressively drawn against the spacers 381, which are drawn against the exterior of the mounting plates 132. Similarly, the mounting plates 132 are compressively drawn against the washers 344 and the inner sleeve 328 of the bushed connectors 26, 28 to clamp the brake assembly mounting bracket 370 to the mounting plates 132.

A benefit of the third embodiment of the invention is that the longitudinal bending forces acting on the axle are effectively absorbed by the resilient axle-to- beam connection between the axle mounting assembly 130 and the rigid trailing arm 18. That is, in other words, since the inner sleeve 328 of the bushed connector 26, 28 rigidly connects the axle mounting assembly 130 and the brake assembly mounting bracket 370, and the outer sleeve 326 of the bushed connector 26, 28 is rigidly connected to the rigid trailing arm 18, the inherent resilient movement of the inner sleeve 328 with respect to the outer sleeve 326 of the bushed connector enabled by the compression of the elastomeric annulus 340 disposed between the inner sleeve 328 and outer sleeve 326, resiliently connects the axle mounting plates 132, axle tube 12, and the brake assembly mounting bracket 370 to the rigid beam 18. This resilient axle-to-beam connection permits the torsional forces applied to the trailing arm to be substantially absorbed by the bushed connectors 26, 28 before the torsional forces are applied to the axle 12.

Another advantage of the invention is that the brake actuator 80 and S-cam bearing 206 are conveniently mounted to the axle mounting assembly 130 through the brake assembly mounting bracket 370 instead of mounting the brake actuator 80 and the S-cam bearing 206 to the axle 12. In prior trailing arm suspensions, it was common to rigidly mount the brake actuator 80 and the S-cam bearing 206 directly to the axle 12, since for proper brake operation, it is necessary for the brake actuator 80 and S-cam bearing 206 to remain aligned with the brake 344, which is mounted directly to the axle. Unfortunately, the direct mounting of the brake actuator 80 and the S-cam bearing 206 to the axle 12 previously required welding brackets directly to the axle, which may cause torsional force-induced stress risers in the axle. The current invention addresses the difficulties and disadvantages of mounting the brake actuator 80 and S-cam bearing 206 directly to the axle by rigidly mounting the brake actuator 80 and S-cam bearing 206 to the axle mounting assembly 130 by the brake assembly mounting bracket 370, effectively creating a rigid unitary structure from the axle mounting assembly 130, brake assembly mounting bracket 370, brake actuator 80, and S-cam bearing 206.

FIGS. 11 and 12 illustrate a fourth embodiment trailing arm suspension according to the invention. The fourth embodiment trailing arm suspension is substantially identical to the third embodiment except for the brake assembly mounting bracket 470. Therefore, like parts in the fourth embodiment will be identified by like numerals and only the third embodiment brake assembly mounting bracket 470 will be described in detail.

The brake assembly mounting bracket 470 comprises a laterally extending actuator platform 474 comprising spaced arms 471, 473, which connect at an apex 475. Mounting bolt openings 478 along with a pushrod opening 476 are formed in the arm 473. Similarly, a pushrod opening 477 is formed in the arm 471. The actuator 80 is mounted to the arm 473 by inserting the actuator mounting bolts 375 and actuator rod 82 through the mounting bolt openings 478, and pushrod openings 476, 477, respectively. Nuts 377 are then threaded onto the brake actuator mounting bolts to compressively retain the actuator to the arm 473. The brake assembly mounting bracket 470 further comprises mounting flanges

479, 481 that, respectively, extend away from the arms 471, 473. Each of the mounting flanges 479, 481 include openings through which the bushed connector mounting bolts 342 are received and threaded with nuts 346 to compressively retain the bracket assembly mounting bracket 470 to the axle mounting plates 132. The brake assembly mounting bracket 470 additionally includes a bearing mount 483 having a generally L-shaped cross section and which extends outwardly and upwardly from the mounting flange 479. The bearing mount 483 receives and mounts the S-cam bearing 206.

The fourth embodiment of the underslung trailing arm suspension having a rigid beam with a resilient axle-to-beam connection with a brake assembly mounting bracket 470 rigidly connected to the axle mounting plates 132 provides the same advantages as the second embodiment. Namely, the axle 12 is compressively retained by the axle mounting assembly 130, the axle mounting assembly 130 is resiliently mounted to the rigid beam and enables relative movement between the beam and the axle, and the S-cam bearing and brake actuator are rigidly connected to the axle bracket.

The foregoing description of a trailing arm suspension is for purposes of illustration and is not intended to be a limitation on the types of suspensions on which the axle mounting assembly according to the invention can be used. For example, the axle mounting assembly according to the invention can be used on all different types of trailing arm suspensions, on leaf spring suspensions, and on combinations of the two. Further, the suspensions utilizing the axle mounting assembly according to the inventions can be used on trucks, trailers, buses and other types of heavy-duty vehicles, including off-road vehicles as well as on-road vehicles. Reasonable variation and modification are possible within the scope of the foregoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims.

Claims

CLAIMSWhat is claimed is:

1. In a vehicle suspension for mounting ground-engaging wheels to a vehicle frame, the suspension system comprising a pair of trailing arm assemblies, each trailing arm assembly is adapted to be mounted to a different side of the vehicle frame and comprising an arm, and at least one wheel carrying axle mounted to each of said arms through an axle mounting assembly, the improvement comprising: a brake assembly bracket mounted to each of the axle mounting assemblies; a brake actuator mounted to each of the brake assembly bracket; and an S-cam bearing mounted to each of the brake assembly brackets.

2. The vehicle suspension according to claim 1 wherein the axle mounting assembly comprises at least one hollow wrapper band rigidly connected to the axle and at least one axle mounting plate resiliently connected to one of the arms and rigidly mounted to the at least one wrapper band.

3. The vehicle suspension according to claim 2 wherein the hollow wrapper band has a width greater than a thickness and circumscribes the axle with inner surface portions shaped to conform to at least a portion of at least two sets of diametrically opposed and circumferentially spaced external surfaces of the axle.

4. The vehicle suspension according to claim 3 wherein the hollow wrapper band is under a tension sufficient to compress the axle at each of the inner surface portions of the wrapper band and evenly distribute a compressive load on the axle across the at least two sets of diametrically opposed external surfaces of the axle sufficient to prevent relative movement of the axle with respect to the wrapper band under ordinary service conditions.

5. The vehicle suspension according to claims 2-4 wherein the brake assembly bracket is mounted to the at least one wrapper band.

6. The vehicle suspension according to claims 2-5 wherein the brake assembly bracket is removably mounted to the at least one wrapper band.

7. The vehicle suspension according to claims 1-6 wherein the S-cam bearing is bolted to the brake assembly bracket.

8. The vehicle suspension according to any of claims 1 -7 wherein the brake assembly bracket comprises a coupling portion mounting the brake assembly bracket to the axle mounting assembly, a brake actuator mounting portion to which the brake actuator is mounted, and an S-cam bearing mounting portion to which the S- cam bearing is mounted.

9. The vehicle suspension according to claim 8 wherein the coupling portion comprises a side plate, generally perpendicular to the axle and having an inner edge partially circumscribing the axle.

10. The vehicle suspension according to claim 9 wherein the at least one wrapper band has multiple ears, each ear having an opening, and the arcuate plate has corresponding openings formed along the inner edge, and fasteners pass through the ear openings and inner edge openings to mount the brake assembly bracket to the wrapper band.

11. The vehicle suspension according to claim 10 wherein the brake actuator mounting portion includes a front plate extending transversely from one of the side plate and an S-cam bearing mount is mounted on the side plate near another end of the side plate.

12. The vehicle suspension according to claim 8, and further comprising at least one bushed connector resiliently connecting the axle mounting assembly to one of the arms, and the brake assembly bracket is connected to the bushed connector.

13. The vehicle suspension according to claim 12 wherein the bushed connector comprises an inner sleeve, an outer sleeve, and an elastomeric annulus disposed between the inner and outer sleeves, the outer sleeve is rigidly connected to the arm, the inner sleeve is rigidly connected to the axle mounting bracket and to the brake assembly bracket.

14. The vehicle suspension according to claim 12 or 13 wherein the brake actuator mounting portion extends laterally from an end of coupling portion and the S-cam bearing portion is substantially coplanar with the coupling portion.

15. The vehicle suspension according to and of claims 12-14 and further comprising two bushed connectors resiliently mounting the brake assembly bracket to the arm.

16. The vehicle suspension according to claims 2-12 wherein there are two relatively narrow wrapper bands connected to each of the arms.

17. The vehicle suspension according to claim 16 wherein each of the brake assembly brackets is rigidly connected to two wrapper bands.

18. The vehicle suspension according to any of claims 1-17 wherein the arms are mounted generally above the axle and the brake assembly brackets are mounted generally below the axle.

19. The vehicle suspension according to any of claims 1-17 wherein the arms are mounted generally below the axle and the brake assembly brackets are mounted generally below the axle.

20. The vehicle suspension according to claims 1-19 wherein the brake assembly bracket comprises first and second ends, the brake actuator is mounted near the first end, and the S-cam bearing is mounted near the second end.