Suspension system with wishbone stabilization assembly

A hanger depending downwardly from a side of the chassis supports a torque beam and a lift spring which is mounted between a plate and the torque beam. A cross channel assembly is connected between the hangers of opposite sides of the vehicle. The forward central portion of a wishbone stabilizer assembly is connected to the center of the channel assembly by a special resilient spring and bushing assembly. The wishbone stabilizer assembly has diverging arms. The rearward end of each arm is journalled on a bushing assembly that is mounted in an axle seat assembly. Similarly, the rearward end of the torque beam is journalled on a bushing assembly that is also mounted in the axle seat assembly, and in a longitudinal direction, the stabilizer arm and the torque beam act as a parallelogram to stabilize the axle seat and maintain the pitch of the axle. An air spring is mounted between the axle seat and the chassis and is located directly above the axle. The wishbone stabilizer assembly provides a component of parallelogram stabilization and eliminates the need for a sway bar. The resulting suspension system is highly compact and free from interference with a vehicle drive shaft.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates to a vehicle suspension system and particularly to a 
vehicle suspension system that incorporates a special wishbone 
stabilization assembly that cooperates with a torque beam to define 
parallelogram stabilization on both sides of the axle and incorporates a 
lift spring, all in a highly compact air spring suspension. 
This suspension system is particularly suited for a pusher or trailing axle 
application. The suspension system is extremely compact with various 
components serving a plurality of functions. In brief, the suspension 
system includes a hanger assembly that depends downwardly from a side rail 
of the vehicle chassis. The hanger assembly provides a connection for a 
bushing assembly on which the end of a torque beam is mounted. The hanger 
assembly also provides a seat for supporting the bottom end of a lift 
spring with the top end being connected to the torque beam. The lift 
spring has a built-in bumper that limits downward travel of the axle. 
Also, a shockabsorber becomes fully extended to assist the lift spring in 
this limiting function. 
A cross channel member is connected between the hanger assembly and a like 
hanger assembly on the opposite side of the vehicle. The cross channel 
assembly serves as a stabilizing connection between the hanger assemblies. 
The cross channel assembly also provides a point of installation for the 
forward central portion of a wishbone stabilizer assembly. The wishbone 
stabilizer assembly comprises a pair of diverging arms that are joined 
together at their forward ends where the assembly is connected to the 
cross channel assembly by a unique bushing and marsh spring assembly. 
An axle seat assembly provides connections to the axle. It also provides 
connection points for the rearward ends of the torque beam and one of the 
diverging arms of the wishbone stabilizer assembly. The axle seat assembly 
further provides a connecting point for a shock absorber and through its 
connection to the axle, provides a connection for a bracket to which an 
end of a hydraulic cylinder is connected, the other end being connected to 
the tie rod. 
The wishbone stabilizer assembly provides a lower component of a 
parallelogram, the upper component of which is defined by the torque beam 
and both components are pivotally connected between the hanger and cross 
channel assembly and the axle seat assembly. The wishbone stabilizer 
assembly also provides lateral stabilization and eliminates the need for a 
sway bar. Thus the wishbone stabilizer assembly provides a common link 
between the left and right side suspension systems and provides the lower 
parallelogram component for both sides in cooperating with their 
respective torque beams. 
The special resilient bushing and marsh spring assembly that connects the 
wishbone stabilizer assembly to the cross channel assembly allows for 
conical movement of the wishbone stabilizer assembly. This complex 
connection accommodates the complex movements of the wishbone stabilizer 
assembly, such as occur when one side only of the vehicle moves vertically 
relative to the axle. 
The diverging arms of the wishbone stabilizer assembly cooperate with the 
torque beams to provide lateral stabilization and eliminate the need for a 
sway bar or lateral guide. Because the two torque beams on opposite sides 
of the vehicle prevent the axle from moving longitudinally, and because 
the angular convergence of the arms of the wishbone stabilizer assembly 
would require longitudinal movement of the axle in the event of sway, the 
resulting combination eliminates sway of the axle. 
The parallelogram maintains constant pitch or caster of the axle. Also, by 
preventing the axle seat from rotating about a transverse axis, the 
parallelogram maintains the attitude of the air spring, utilizing its full 
stroke.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
This suspension system 10 is shown installed on a vehicle of the kind 
having an axle 12 located below a chassis that has a left side rail 14, 
and it will be understood that there is a similar right side rail on the 
right side of the vehicle. A wheel hub 16 is supported by the axle 12, and 
a tie rod 18 is connected between the wheel hub 16 and another wheel hub 
on the opposite side of the axle 12 in the manner known in the art. It 
will further be understood that the components illustrated and described 
as being located on the left side of the vehicle have counterpart 
components on the right side of the vehicle. 
The components of the suspension system 10 that are on the left side of the 
vehicle (and that are duplicated, but now shown, on the right side of the 
vehicle) include a hanger assembly 19 that has a reinforced mounting 
bracket 20 connected to the side rail 14 by a plurality of bolts 22. The 
bracket 20 includes a horizontal plate 24 to which a vertical U-channel 26 
is welded. The U-channel 26 has side walls 28 and 30 joined to a front 
wall 32. The side walls 28 and 30 have cutaway sections 34 that provide a 
bottom seat 36 to which a lift air spring 38 can be connected by bolts 40. 
A bottom plate 42 is welded to the vertical channel member 26 and extends 
inboard, which allows a vertical connecting plate 44 to be welded both to 
the bottom plate 42 and to the side wall 30. A cross channel assembly 46 
includes two channel members 48 and 50 that are fastened to opposite sides 
of the connecting plate 44 by a plurality of bolts 52. Over their length, 
separation between the channel members 48 and 50 is maintained by a 
centrally located spacer plate 54. This spacer plate provides an overall 
composite thickness between the channel members and the spacer plate of 
about 3/4 inch. The cross channel assembly 46 is connected to a similar 
hanger assembly on the opposite side of the vehicle. 
A fabricated spring seat 58 has a lower plate 60 by which it is connected 
to the axle 12 by a plurality of bolts 62. The spring seat 58 also has an 
upper plate 64 to which an air spring 66 is connected. The upper side of 
the air spring 66 is connected to a bracket 68 that is fastened by bolts 
70 to the side rail 14. 
The plate 68 has a section 72 that extends forwardly and inwardly of the 
spring 66. A pair of parallel spaced dogs 74 and 76 are welded to the 
section 72. In addition, two channel members 78 and 80 are welded to and 
project upwardly from the axle seat assembly 58, and the angle members 78 
and 80 have spaced parallel sides 82 and 84. 
A torque beam 86 has an end journalled on a bushing assembly 88 that is 
mounted between the side walls 28 and 30 of the hanger 18. The other end 
92 of the torque beam 86 is journalled on a bushing assembly 94 that is 
mounted between the legs 82 and 84 of the angle members 78 and 80. A plate 
96 is welded to the torque beam 86, and the upper side of the lift spring 
38 is connected to the plate 96 by bolts 98. 
A shock absorber 100 has an upper end 102 pivotally connected to a bracket 
104 that extends from the hanger assembly 19. The lower end 106 of the 
shock absorber 100 is pivotally connected to the axle seat assembly 58. 
It will be understood that similar suspension components are installed on 
the other side of the vehicle These include components corresponding to 
the hanger assembly 18, the lift air spring 38, the axle seat assembly 58, 
the air spring 66, the bracket 68, the torque beam 86 and the shock 
absorber 100. It will be noted that there is no sway bar or lateral guide. 
A wishbone stabilizer assembly 110 extends between the suspension assembly 
10 and the suspension assembly that is on the opposite side of the 
vehicle. The wishbone stabilizer assembly 110 has a pair of diverging arms 
112 and 114 having ends 116 and 118, respectively, that merge together and 
are welded to an end plate 120 as well as top and bottom plates 122 and 
124. Also welded to this assembly is a metal sleeve 126. 
A hole 128 is cut through the assembly consisting of the channel members 48 
and 50 and the spacer plate 54. A resilient bushing 130 is positioned 
within the hole 128, and an elongated one-inch bolt 132 extends through 
the metal sleeve 126 and the resilient bushing 130 with the head of the 
bolt bearing against the end of the sleeve 126. A nut 134 threads against 
a plate 136. 
A marsh spring 138 is compressed between the plate 120 and the channel 
member 50. Another marsh spring 140 is compressed between the plate 136 
and the channel member 48. Each marsh spring 138 and 140 is initially 
about 3 1/4 inch outside diameter and 11/4 inch long. After tightening the 
bolt 132 and nut 134, these marsh springs should be reduced to lengths of 
about 3/4 inch each. Suitable provisions, such as a cotter key (not shown) 
are provided for locking the nut 134 in its tightened position. 
At their opposite ends, each of the diverging arms 112 and 114 is formed 
with an outer bushing sleeve 144. The sleeve end 144 of the arm 112 is 
journalled on a bushing assembly 146 that is supported between the ears 74 
and 76 of the axle seat assembly 58. The sleeve 144 of the arm 114 is 
similarly journalled on a bushing assembly (not shown) on the right side 
of the vehicle. A reinforcing bar 148 extends between the two arms 112 and 
114 and is welded to them to strengthen the wishbone stabilizer assembly. 
A support bracket 150 is connected to the axle 12 by the bolts 60. A double 
acting hydraulic cylinder 152 is installed between the bracket 150 and the 
tie rod 18 by way of a clamp 154. The double acting hydraulic cylinder 152 
stabilizes the wheels in the manner known in the art. 
Installation and Operation 
This suspension system 10 can be readily installed quickly with 
conventional wrenches. The hanger assembly 19 is installed by connecting 
the bolts 22 to the side rail 14. The bracket 68 is also installed by 
connecting the bolts 70 in place. The cross channel assembly 46 is 
connected by the bolts 52 to the hanger assembly 19 (and to the 
corresponding hanger assembly on the opposite side of the vehicle). The 
axle seat assembly 58 is bolted to the axle 12 and the air spring 66 is 
installed. Likewise, the torque beam 86 is installed on the bushing 
assemblies 88 and 94, and the lift spring 38 is installed. The wishbone 
stabilizer assembly is readily installed by mounting the bushing 130 in 
place and extending the bolt 132 through the sleeve 126, the marsh spring 
138, the bushing 130, the marsh spring 140, and the plate 136 and 
tightening the nut 134 to compress the marsh springs. 
The bushing assembly 146 is installed to connect the end 144 to the ears 74 
and 76 of the axle seat assembly 58. There is a similar connection of the 
end of the other arm 114 to an axle seat assembly on the other side of the 
vehicle. 
It should be noted that the wishbone stabilizer assembly 110 is below a 
drive shaft of the vehicle. Therefore, even though the arms 112 and 114 
merge to the center of the vehicle, they do not interfere with the drive 
shaft. The torque beam 86 is wholly outboard of the drive shaft, so 
interference is thereby avoided. Even when the axle 12 moves upwardly 
relative to the vehicle chassis, interference is avoided because the outer 
ends of the arms 112 and 114 are outboard of the drive shaft. The cross 
member 148 is located far enough forward to avoid interference with the 
drive shaft. 
The wishbone stabilizer assembly 110 cooperates with the torque beam 86 (on 
each side of the vehicle) to provide parallelogram stabilization of the 
pitch of the axle 12. In other words, in a longitudinal direction, as 
viewed in FIG. 1, the torque beam 86 and the stabilizer assembly arm 112 
form a parallelogram. In addition, the wishbone stabilizer assembly 110 
provides lateral control and provides a common link between the left and 
right sides of the suspension assembly so that no sway bar is required. 
The suspension system is very compact with the lift spring 38 between the 
seat 36 and the torque beam 86 allowing for raising of the axle 12 when 
the vehicle is not loaded. The cross channel assembly 46 provides 
stability between the hanger assemblies. It also integrates the two hanger 
assemblies into a single interconnected component. At the same time, it 
provides a connection point for the forward central portion of the 
wishbone stabilizer assembly 110. 
Both the air spring 66 and the lift spring 38 have internal bumpers, which 
are of conventional design and construction. The internal bumper in the 
air spring 66 acts as a stop to limit upward movement of the axle 12. The 
internal bumper in the lift spring 38 works in conjunction with full 
extension of the shock absorber 100 to limit downward movement of the axle 
12. 
There are various changes and modifications which may be made to the 
invention as would be apparent to those skilled in the art. However, these 
changes or modifications are included in the teaching of the disclosure, 
and it is intended that the invention be limited only by the scope of the 
claims appended hereto.