MXPA01011132A - Vocational air ride tandem axle suspensions - Google Patents

Abstract

A vocational vehicle (i.e. truck or trailer intended for off-road operation) comprising a chassis (21) mounted on a tandem axle suspension (5, 6) and having lateral stability in addition to roll and fore-and-aft stability. Roll and fore-and-aft stability are provided by a suspension sub-assembly comprising the stabilizer or cross tube (8) of the suspension and a crank arm (14) fixedly mounted on each end of the stabilizer tube (8) with its distal end pivotally attached to the adjacent sides of the chassis (21). Lateral stability is provided by a transverse torque rod (25) interconnected between the rear axle (6) and the chassis (21).

Description

AXIS SUSPENSIONS IN TANDEM OF DISPLACEMENT OF AIRÉ PROFESSIONALS Background of the Invention This invention relates to so-called "professional" heavy duty trucks and trailers adapted for various cross-country work such as concrete mixer trucks, log haul trucks and other trucks that transport heavy loads and which are required to operate on uneven terrain and uneven terrain under cross-country conditions. These trucks must also be able to travel on roads. Suspensions of the type to which the present invention refers use tandem axes operatively interconnected by rockers on opposite sides of the vehicle. At their opposite ends, the rocker arms are pivotally connected to the ends of the axes with the rockers interconnected by a transverse cross tube connected pivotally to the midpoints of the rockers. A plurality of airbags are mounted in a novel arrangement on the upper portions of the rockers directly behind the chassis members extending longitudinally in supporting relationship therewith. A torsion bar is connected between the rear axle and the structure to withstand the lateral suspension forces as the vehicle rotates. The stabilizer characteristics are incorporated in the suspensions according to the present invention in order to provide stability for cornering, lateral stability and steering stability (longitudinal) for the associated vehicles with which those suspensions are employed. In view of the foregoing, it will be noted that the object of the invention, established in a general manner, is the provision of improved and novel tandem axle suspensions for trucks destined for cross-country operation on rugged terrain conditions using rocker arms interconnecting axles tandem and that incorporate structures that provide stability for inclination in curves, lateral stability and longitudinal stability. A further object of the present invention is the provision of air displacement suspensions using airbags or spring-loaded air shocks operating at or below a pressure of about 100 pounds per square inch (7.03 kg / cm2) and that provides on-site charging capabilities. Other objects of the invention will be obvious to those skilled in the art and will be apparent thereafter. For a more complete understanding of the nature and scope of the invention, reference may be made to the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings in which: Brief Description of the Drawings Figure 1 is a side elevational view of a tandem axle suspension for a professional truck or trailer that uses airbags to provide load support by air displacement and incorporates a sub-assembly stabilizer structure which provides stability for tipping curves and longitudinal stability and, a transverse torsion bar placed to provide lateral stability. Figure 2 is a top plan view of the suspension shown in Figure 3 omitting portions on one side that are duplicated on both sides; Figure 3 is a side elevational view of a crank arm that forms an element of the stabilizer structure of the suspension subassembly; Figure 4 is a longitudinal sectional view taken on line 4-4 of Figure -3; Figure 5 is a longitudinal view taken on line 5-5 of Figure 6 of a stabilizer tube forming another element of the sub-assembly stabilizer structure; and Figure 6 is an end elevational view taken on line 6-6 of Figure 5.

The tandem axle suspension shown in Figs. 1 and 2 is conventional in that it comprises a front axle generally indicated in FIG., a rear axle indicated generally in 6, front and rear wheels indicated generally in 7-7 mounted on the opposite ends of axes 5 and 6, a stabilizer or cross tube indicated generally in 8 and a pair of rockers indicated generally 10-10. The opposite ends of the rocker arms 10 are pivotally supported behind the ends of the axes 5 and 6 by pivot joint structures of the known type indicated generally at 11-11. The details of said pivot assemblies and structures are shown and described, for example, in Patent No. 4,699,399, dated August 13, 1987, the description of which is incorporated herein by reference. The ends of the stabilizer tube 8 extend in pivoted relationship through bearings at the intermediate points of the tandem axes 10. The opposite ends 12-12 of the stabilizer tube 8 project from the outer sides of the rocker arms 10. The stabilizer tube 8 it is generally triangular in its cross section so that the projecting ends 12 provide a fixed coupling connection with a crank arm 14 on each side of the suspension. The interior 15 of the proximal end 16 (figures 3 and 4) of each crank arm 14 is generally triangular in shape to fit in coupling relationship with a triangular end 12 of the stabilizer or cross tube 8 thus avoiding any play between the crank arms 14 and the ends 12 of the stabilizer tube on which the crank arms are operatively mounted. Each installed crank arm 14 is tilted up and forward as shown in Figure 1 with its distal end 17 pivotally connected to a pin 18 projecting laterally from a suspended support 20 mounted on the side of each of the arms of lateral steering structure 21 forming components of the chassis that is mounted on the suspension. The side frame members 21 are supported on respective rockers 10 by a spring air cushion or air bag 19 and a pair of rear spring air cushions 22. The upper ends of the air bags 19 and 22 are connected to fittings 23-23 on the lower sides of the respective structure members 21. It will be seen from FIGS. 1 and 2 that while the spring-loaded air cushions or airbags 19 and 22 are mounted equidistantly one with respect to the other in the upper parts of the rocker arms 10, they are not located symmetrically with respect to the stabilizing tube 8 or the intermediate points of the rockers 10. Instead, the center or half of the spring-loaded air cushion 22 is placed appreciably towards the rear of the intermediate point of the rocker 10 and backwards with respect to the stabilizer tube 8. This non-symmetrical mounting arrangement provides Free space for suspended supports of structure 20 and is compensated for by use of an air damper with front spring 19 which is larger than smaller rear spring air shocks 22. With the distal ends of the crank arms 14 which are pivotally connected on pins 18 to supports 20 and with their proximal ends rigidly mounted on opposite ends of cross tubes 8 it will be seen that stability is provided for cornering for the vehicle. Likewise, this stabilizing subassembly also provides steering stability (ie, longitudinal) for the vehicle that includes resistance to braking and acceleration forces. In order to also provide lateral stability, a torsion bar 25 (FIG. 2) is pivotally mounted at one end 26 on an attachment 27 at the top of the rear axle 6 and pivotally connected at the opposite end 28 to a bearing 30 mounted in a chassis swinging arm 21. Lateral forces applied to the rearmost wheels in the tandem suspension are transmitted from the rear axle 6 directly to the structure of the vehicle by the torsion bar 25. Since the rear part of the frame member 21 is attached to the shaft 6 the rear part of the rocker 21 is fixed relative to the structure of the vehicle in the lateral direction. The front axle 5 does not have a torsion bar. Since the lateral forces are transmitted from the shaft to a rocker 10 the front of which is allowed to move or translate a discrete amount in the direction of the applied lateral force until the center of the rocker arm is sufficiently misaligned with its inner bearing and bending occurs. Therefore the translation stops and the lateral forces are transmitted from the frontal axis to the rocker, towards the stabilizing tube, finally resisted by the structure of the vehicle. The advantages of this lateral fixation system are twofold: First, if a torsion bar is mounted to the front axle during the high rocker joint, the translation caused by the front and rear transverse torsion bars would cause a rocker 10 to flex around its central bearing prematurely because the lateral fixation would be "overdefined" that is there would be three lateral fixation points instead of 2. However, only with a posterior transverse torsion bar a balancer 10 can articulate a greater displacement and accommodate larger In the second place, because the front of a rocker moves laterally in the direction of the interior of the vehicle that turns in a circle, the rim direction angles resulting from the tandem axes would be towards the inside of the circle that rotates, increasing proportionally with increasing lateral strong and imposing a moment ro on the chassis opposite to that of the steering input, and therefore tending to autocorrect the deviations to a straight vehicle path. This subdirection of lateral force deformation is a desirable condition, promotes the stable and predictable handling and control of the vehicle.

Those skilled in the art will understand that certain changes in the suspension can be made without departing from the scope of the invention as defined in the claims. For example, instead of the stabilizing tube 8 having a generally triangular shape and the crank arms having connectors of attachable shape, other shapes such as square or hexagonal can be used. Likewise, the projecting ends 12 of the stabilizing tube 8 could be axially grooved and the connectors of the proximal ends 16 of the crank arms grooved in a dockable manner.

Claims (7)

1. In a tandem axle suspension for a vehicle chassis that includes longitudinally extending chassis side frame members, said suspension having longitudinally spaced axles with wheels mounted on opposite sides of the axles, a rocker extending longitudinally between the ends of the axles on each side of the suspension and supported at their opposite ends by adjacent ends of the axes and a stabilizing tube extending between the intermediate points of said rocker in pivoted relation thereto, the improvement providing stabilization for inclination in curves and longitudinal of combined vehicle comprising, a plurality of spring-loaded air springs on each of the rockers in chassis support relationship with one of the longitudinally extending chassis side frame members, a crank arm on each side of said suspension fixedly fixed at its end p next to the adjacent end of said stabilizer tube and pivotally connected at its distal end to a fixed support on a chassis side frame member at a front location of said stabilizing tube and on the front axle whereby each crank arm is inclined towards up and forward. The crank arms in constraint with the stabilizer tube that provide stability for bending in curves and longitudinal to a vehicle comprising the vehicle's chassis and suspension.

2. In the improvement in the tandem axle suspension according to claim 1, the ends of the stabilizing tube projecting on the outer sides of the rockers and the proximal ends of the crank arms are fixedly secured to said projection ends for rotational movement with them.

3. In the improvement according to claim 2, the projecting stabilizing tube ends are formed externally to engage in a fixed relationship with the proximal ends of said crank arms.

4. In the improvement according to claim 3, projecting ends of said stabilizing tube having a generally triangular outer shape.

5. In the improvement of the tandem axle suspension according to claim 2, the plurality of spring-loaded air springs that provide the complete support of said vehicle frame on said suspension and the spring-loaded air springs which are placed in non-symmetrical shape on the rockers with respect to the stabilizer tube.

6. In the improvement according to claim 5, three equidistanced spring air shocks constitute the plurality with the spring air damper which is placed on the cross tube with its center located rearwardly of the center of said cross tube. The improvement according to claim 1, comprising a transverse torsion bar pivotally connected at one end to said longitudinal axis and pivotally connected at its opposite end to said chassis to provide lateral stability to said vehicle.