WHEEL STRAIGHTENING MECHANISM

FIELD OF INVENTION

The present invention relates to the self- steer axle and self- steer lift axle for medium and heavy duty vehicle, and more particularly to a retrofit wheel straightening mechanism, which limits the self steer-ability of the axle during reversing the vehicle and lifting the axle. The retrofit wheel straightening mechanism acts as steering stabilizer when the vehicle is operated in normal forwarded direction.

BACKGROUND OF INVENTION

Self-steer axle is commonly used in medium and heavy duty trucks, trailers and multi axle bus to extend the tire life by reducing the tire scrub and wear. If a lift axle mechanism is attached with the self-steer axle, the axle can be lifted-off the road surface when the vehicle is operated unladed and partially loaded conditions, therefore it is called self steered lift axle suspension. The self steer axle is made self steering by adjusting caster angle of the wheels so that the drag of the wheels as the vehicle moves in the forward direction.

The suspension system including wheel assembly steers automatically in response to the steering of the front axle of the vehicle. When the vehicle is operated in reverse condition, the self-steer response the axle making difficult to operate the vehicle due to the tires tend to track improperly. In fact, the tires tend to steer completely to one side or the other, in quite abruptly manner. It leads to affect the maneuverability of the vehicle and to damage the suspension system.

The self steer axle is generally lifted off the road surface in multi-axle vehicle, having more than 3 axles, especially during reversing the vehicle. In this period, the load which carries the lift axle is transferred to the other axles which are engaged to the road surface.

FIG. 1 shows the schematic of a multi axle truck having a self steer axle (1) in reverse operation. The self steer axle is attached to the chassis frame (2) of the vehicle to increase the load carrying capacity of the vehicle. The self steer-able axle is lifted-off from the road surface during reversing the vehicle. However, in tractor vehicle, the self steer axle can't be lifted during reversing the vehicle, because especially, the other axles will be overloaded. Therefore, the suspension system of the axle, engaged to the road surface, experiences heavy stresses. This problem has been solved using a mechanical device which locks or limits the steer-ability of the wheels when the vehicle is especially operated in reverse condition.

FIG.2 shows the schematic of a tractor vehicle having a self steer-able axle in reverse operation. The self steer-able axle is attached to the chassis frame (2) of the vehicle to increase the load carrying capacity of the vehicle. In the tractor vehicle, the wheel assembly is restricted to self-steer instead of lifting the axle when reversing the vehicle. That is, the wheel assembly is maintained to a straight ahead position. In order to control the steer-ability of the axle, bar lock and pin lock systems are commonly used. These systems are operated pneumatically or electrically. Hydraulic systems using one or more hydraulic actuators are also used to control the steer-ability of the axle. The hydraulic mechanism is activated to hold the wheel assembly in the straight ahead position by applying a force to steering linkages especially to the track rod lever of the axle. In addition, a reverse caster method also used in few self steer lift axles.

The pneumatic pin locking system suffers due to its operational difficulties, whereas the straightening mechanism using hydraulic actuators and reverse caster technology are costly and it suffers due to high maintenance and high self weight. In addition, the reliability of the systems is also less; because theses device have many moving parts. Some time, the pneumatic locking system may not work properly; particularly, the axle may not be locked.

Therefore, vehicle operator has to give more attention during vehicle reversing, (i.e., especially the vehicle should be operated very slowly in reverse condition). When operator uses the pneumatic pin locking system, operator should ensure the wheels are the axle in straight ahead position before operate the lock pin. Therefore, it is difficult to operate the vehicle and it consumes more time to operate in reverse condition. In addition, periodic maintenance and lubrication are required. As the pin lock is a positive lock, the locking mechanism and the axle components of the assembly experience a heavy impact load during abrupt/rapid reverse operation of the axle. Some time, it leads to damage of the components of the axle.

Moreover, a frequent failure is observed in the coil over steering stabilizer, which is commonly used in the self steer axle. It is also observed in many times that the wheel assembly is in turned position after lifting the axle.

In view of the above, the present invention is essentially required to address the above mentioned drawbacks which are found in the commercially available self steer lift axle and self steer axle. The mechanism which is used to solve these problems could also be applied to other types of the self steer axle suspension system and self steer lift axle.

OBJECT OF THE INVENTION

The main object of the present invention is to provide a retrofit wheel straightening mechanism for the self steer-able lift axle for holding the wheel assembly in straight ahead position during reversing the vehicle.

Another object of the present invention is to provide a mechanism for the self steer-able lift axle which is especially for holding the wheel assembly in straight ahead position after lifting the axle.

Another objective of the present invention is to provide a mechanism for the self-steer-able axle which should be fitted to the wheel assembly without any modification.

Another objective of the present invention is to provide a mechanism for the self steer-able axle which should assist the wheel assembly to align straight position slowly along to the rolling of the tire when the vehicle is operated in reverse direction.

Another objective of the present invention is to provide a mechanism for the self steer-able axle which should work properly even in rapid reverse operation.

Yet another objective of the present invention is to provide a retrofit wheel straightening mechanism for the self steer-able axle which prevents the damage of the axle components during reversing the vehicle.

Yet another objective of the present invention is to provide a retrofit mechanism for the self steer-able axle which should absorb road shock and reduce oscillation.

Another objective of the present invention is to provide a retrofit mechanism which should reduce the shimmy which is generally observed in the self steering parallelogram type lift axle.

Another objective of the present invention is to provide a mechanism which should be manufactured easily and inexpensive.

Another objective of the present invention is to provide a simple mechanism which should also work as a steering stabilizer when the vehicle is operated in normal forward direction.

Another objective of the present invention is to provide a simple mechanism which should give better life than the coil over spring steering damper.

SUMMARY OF THE INVENTION

The present invention which achieves the objectives, relates to a wheel straightening mechanism for a self-steerable axle and a self-steerable lift axle. This is a simple retrofit pneumatic type actuator mechanism for straightening the wheel assembly of the vehicle during reversing the vehicle and lifting the axle. The mechanism consists of a pair of pneumatic actuators, a pair of brackets, a pair of push rod ends, and a pair of lock nuts with lock washers, solenoid pressure control or reduction valve, and a pair of straightening levers. The pneumatic actuator is mounted to the bracket which is simply connected to bottom air bellow mounting bracket connected to the axle through mechanical means. The push rod end is screwed and locked with the push rod of the pneumatic actuator.

A pneumatic control system, having a pressure reduction valve which supplies compressed air to the actuators is provided with an appropriate pressure whenever need. The pressure reduction valve is mounted to the chassis frame of the vehicle through suitable brackets. The wheels assembly is maintained in straight ahead position by inflating the pneumatic actuators. The axle is changed to self-steer mode by reducing air pressure in the pneumatic actuators. Thereby, the retrofit wheel straightening mechanism is worked as a steering stabilizer when the vehicle is operated in normal forward motion.

The straightening lever, having appropriate length and round shape in its forefront side, is connected to the female threaded portion, which is in the wheel assembly, where the steering arm is commonly connected in the axle. Similar one more arrangement is connected to the other side of the wheel assembly. When the vehicle is operated in reverse direction, the pneumatic actuators are activated. Therefore, the push rods of the actuators extend and push the straightening lever attached to the wheel assembly of the axle, so that the wheels tend to align straight ahead position due to a moment generated in the kingpins of the axle.

Once, the wheels have been straightened, both the pneumatic actuators together maintain the wheels assembly in a straight ahead position until they release the compressed air from the pneumatic actuators. The pneumatic actuators are also actuated during the axle is lifted. Thereby, the wheels are kept straight ahead position to the vehicle during reversing the vehicle and lifting the axle. In addition, the retrofit wheel straightening system acts as steering stabilizer to reduce the wheel oscillation, which is due to road shock and wheel shimmy in normal operation of the vehicle.

The solenoid operated pressure reduction valve is provided for allowing the compressed air to the actuators at an appropriate pressure in normal mode of operation. During the process of disengaging, the reverse gear, the axle automatically reverts back to normal self-steering mode to move forward direction. The self steer-able lift axle suspension is used in the heavy duty multi axle vehicle for lifting the axle when it is not required. The wheel assembly of self steer-able lift axle is^ forcefully straightened during reversing the vehicle and lifting the axle.

The wheel straightening mechanism according to the present invention enables the wheel assembly to align to a straight position slowly along to the rolling of the tire when the vehicle is operated in reverse direction, thus preventing the damage of the axle and wheel components, during reversing the vehicle.

This improved mechanism allows absorbing road shock and reducing oscillation of vehicle. Also, this wheel straightening mechanism can be manufactured easily and it is inexpensive. The present invention provides a simple mechanism which gives better life than the coil over spring steering damper. Further, this wheel straightening mechanism can be fitted to the wheel assembly without any modification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic view of a multi axle truck having a self steer axle in a reverse operation.

FIG. 2 shows a schematic view of a tractor vehicle having a self steer axle in a reverse operation.

FIG. 3 shows the schematic view of the self steer axle with the wheel straightening mechanism, in accordance to the present invention.

FIG.4 shows the illustration of the self steer lift axle with the wheel straightening mechanism, in accordance to the present invention.

FIG.5 is an assembly view of the wheel straightening mechanism, in accordance to the preferred embodiment of the present invention.

FIG.6 is a view of actuator mounting bracket, in accordance to the preferred embodiment of the present invention.

FIG. 7 is an assembly view of actuator and push rod ends, in accordance to the preferred embodiment of the present invention.

FIG.8 is a view of straightening lever, in accordance to the preferred embodiment of the present invention.

FIG.9 is a schematic view of the bearing bush, in accordance to the preferred embodiment of the present invention.

DETAILED DESCRIPTION

The present invention relates to a retrofit wheel straightening mechanism, which limits the self steer-ability of the axle during reversing the vehicle and lifting the axle. The retrofit wheel straightening mechanism acts as steering stabilizer when the vehicle is operated in normal forwarded direction.

FIG.3 shows the schematic of the self steer axle with the wheel straightening mechanism, in accordance to the present invention. The self steer-able axle assembly (1) is connected to a chassis frame (2). The self-steer-able front axle assembly consists of tire (3), axle beam, track rod lever (5) and track rod (4). The retrofit wheel straightening mechanism, described herein is a pneumatic actuation type mechanism, consists of a pair of pneumatic actuators (6), a pair of pneumatic actuators mounting brackets (12), a pair of push rod ends (7), a pair of lock nuts (20); a pair of lock washers (15), a pair of straightening levers (8), a pair of bearing bushes.

A pneumatic control system, having a solenoid operated pressure reduction valve (not shown in the figure) is provided for supplying compressed air to the pneumatic actuators with an appropriate pressure whenever need. The pressure reduction valve is mounted to the chassis frame (2) of the vehicle through suitable brackets. The wheels assembly is maintained in straight ahead position by inflating the pneumatic actuators. The axle is changed to self-steer mode by reducing air pressure in the pneumatic actuators. Thereby, the retrofit wheel straightening mechanism is worked as a steering stabilizer when the vehicle is operated in normal forward motion.

When the vehicle is operated to reverse direction, compressed air of the vehicle is directed to the pneumatic actuators (6). Therefore, the push rod of the pneumatic actuator (6) is extended and applies a force on the straightening lever (8). Due to the large force exerted in the straightening lever (8), a tortional moment is created in the wheel or tire assembly (3) with respect to the kingpin of the self steer axle (1). Therefore, the wheel assembly tends to align to straight ahead position slowly with reverse rolling of the tire (3) on the road.

FIG.4 shows the view of the self-steer-able lift axle suspension system having retrofit wheel straightening mechanism according to present invention. The self steer-able lift axle assembly (23) is connected to a chassis frame (1). The self steer-able lift axle assembly (23) consists of tire (3), self steer axle (2), track rod lever (5) and track rod (4), kingpin (32), a pair of parallelogram linkage mechanism (24), a pair of ride air bellows (25), a pair of hanger brackets (27), a cross member (28) and a pair of lift axle air bellows (26). The retrofit wheel straightening system is used to straighten the wheel and tire (3) assembly after lifting the axle (1). The pneumatic actuators (6) are activated when the axle is lifted-off from the road surfaces. During activating of the pneumatic actuators (6), the wheel assembly tends to align the straight ahead position slowly. Further, the actuators (6) hold the wheel assembly in straight ahead position. In order to reduce the operation cycle of the retrofit wheel straightening mechanism, the pneumatic actuators are deactivated during switch-off the vehicle.

FIG.5 shows the view of the assembly of the retrofit wheel straightening mechanism. The pneumatic actuator (6) is connected to the pneumatic actuators mounting bracket (12) which is secured rigidly to each side of the bottom air bellow mounting brackets (10) by mechanical means such as fasteners (14) and lock washers (15) through the boss (13). A solenoid operated pressure reduction valve (not shown in the figure) provides compressed air to the pneumatic actuators with an appropriate pressure.

The wheels assembly is maintained in straight ahead position by inflating the pneumatic actuators (6). The axle is changed to self-steer mode by reducing air pressure in the pneumatic actuators (6). Thereby, the retrofit wheel straightening mechanism is worked as a steering stabilizer when the vehicle is operated in normal forward motion. The push rod of the pneumatic actuator (6) is extended and applies a force on the straightening lever.

FIG.6 shows a view of the pneumatic actuator mounting brackets (12) made of steel plates. It has a boss (13). In which a bearing bush (21), made of a wear resistant material preferably aluminum bronze or nylon or oilon coated steel, is forcibly inserted. The pneumatic actuator mounting bracket (12) is secured to the side of bottom air bellow mounting bracket which is connected to the axle assembly (1) of the vehicle by mechanical connectors. The pneumatic actuators (6) are connected to the pneumatic actuator mounting bracket (12) using fasteners.

FIG. 7 shows a view of the assembly view of pneumatic actuators (6) and push rod ends (7). It has a round concave shape head (18) with female threaded nut (29) (or called blind nut). The female thread nut (29) is used to connect the push rod end (7) with the pneumatic actuator (6) which has a male threaded portion (30) at the end of the push rod (31). A round concave shape (18) in push rod is given to the head of the push rod end (7). It limits the slip which occurs in the push rod ends when the push rod (7) pushes the straightening lever (8).

The push rod end (7) is screwed to the push rod of the pneumatic actuators (6). The lock nut (20) is provided to lock the push rod ends (7) with the pneumatic actuators (6). In order to prevent the loosening of push rod end (7) from the pneumatic actuator (6), a lock washer (15) is also placed in it. The lock washer (15) has two rips. After assembly of the push rod end (7) with the pneumatic actuator (6), one rib (not shown) is bent onto lock nut (20) and another rip is bent onto the female thread nut (29) of the push rod ends (7).

FIG. 8 shows a view of straightening lever (8). It is attached to the wheel assembly in the location where the steering arm is usually mounted in the front axle. Therefore, no modification is required in the wheel assembly to mount the straightening lever (8). A special attention is given to fabricate the straightening lever (8). Especially, at the end of the straightening lever (8), a simple round shape head (19) is provided which is mainly to maintain a line contact in between the straightening lever (8) and push rod an end (7) which is mainly to reduce the rubbing action (i.e., friction).

FIG.9 shows the schematic of the bearing bush (21). It is preferably made of a wear and abrasive resistance materials. In the present invention, it may be made of aluminum bronze or nylon or oilon coated steel tube. The nylon or oilon (33) is coated in side of the steel tube (34).

The retrofit wheel straightening mechanism is used as steering stabilizer when the vehicle is operated in forward direction. For that, the compressed air is supplied with an appropriate pressure to the pneumatic actuator (6). In order to supply the compressed air with an appropriate pressure, a solenoid pressure control valve (not shown) is used. The valve controls the steer-ability of the suspension.

In addition, the pneumatic actuators (6), dampen the road shock and the oscillation generated from the road undulates (i.e., debris). As the pneumatic actuators (6) are mounted in opposite orientations, it controls the steer-ability wheel assembly of the axle in both directions (LH and RH) for the vehicle. The appropriate stiffness will be maintained in the pneumatic actuators (6) by selection of the pressure of the compressed air.

The mechanism according to the present invention allows maintaining desired cornering performance criteria such as cornering stiffness and loading of the self-steer-able lift axle (1). The pneumatic actuators (6) reduce down the oscillations caused by wheel shimmy and road shock due to road irregularities experienced in the wheel assembly during vehicle operation; thereby, tracking is stabilized.

The control system provided for the self steer-able lift axle suspension enables sufficient air to pneumatic actuators in the different operations of the vehicle. The control system consists of few direction control valves, a pressure gauge, a control box and a few electrical rocker switches. The control system is not a part of the present invention; therefore, the description of control system is not given in the document.

The wheel straightening mechanism according to the present invention enables the wheel assembly to align to a straight position slowly along the rolling of the tire when the vehicle is operated in reverse direction, thus preventing the damage of the axle and wheel components, during reversing the vehicle. The present invention of wheel straightening mechanism can ve adapted in any vehicle without any modification in the wheel assembly to fit the straightening lever. In this invention, the straightening lever is just connected to the threaded hole provided in the wheel assembly for connecting the steering arm.

The positive lock is replaced by this simple mechanism which just holds the wheel assembly in a straight ahead position by applying a force to a straightening lever. This makes the wheel assembly to align straight line position along with reverse rolling of the tire, thus reducing the tire scrub. This invention allows rapid reverse turning without any difficulties, as the pneumatic actuator uses the compressible fluid, and withstand the road shock and oscillations caused by road undulate.

This mechanism is also operated after lifting the axle to maintain the wheels in straight ahead position. The pneumatic actuators act as steering stabilizer during normal operation like forward movement of the vehicle, by maintaining an appropriate air pressure for the pneumatic actuators.

The present invention provides a simple mechanism which gives better life than the coil over spring steering damper. Further, this wheel straightening mechanism can be fitted to the wheel assembly without any modification. This improved mechanism allows absorbing road shock and reducing oscillation of vehicle. Also, this wheel straightening mechanism can be manufactured easily and it is inexpensive.

Many modifications and other embodiments of the invention may come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. In addition, some changes may be made to these specific embodiments, and such modifications are contemplated by the principle of the present invention. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.

WE CLAIM:

1. A wheel straightening mechanism for a self steer axle, comprises:

a self steer axle assembly (1) attached to the chassis frame (2) of a vehicle, and a pair of straightening levers (8) secured to the wheel assembly (3) of said self steer axle (1);

a pair of pneumatic actuators (6) mounted to the pneumatic actuators mounting brackets (12), wherein the mounting brackets (12) are connected at the both sides of the self steer-able axle assembly (1);

a pair of push rods (7) extending from the pneumatic actuators (6), such that the contact portion of push rods contact with the straightening lever (8),

wherein said push rods (7) apply a force on the straightening lever (8), when actuated by the pneumatic actuators (6), and the wheel assembly (3) of the vehicle align to a straight position.

2. The wheel straightening mechanism as claimed in claim 1, wherein the actuation of pneumatic actuator exerts large force on the straightening lever (8), and a tortional moment is created in the wheel assembly (3) with respect to the kingpin of the self steer axle (1) of the vehicle.

3. The wheel straightening mechanism as claimed in claim 1, wherein the pneumatic actuators (6) are actuated to straighten the wheel assembly (3), when the vehicle experiences reverse rolling of the tire (3) on the road.

4. The wheel straightening mechanism as claimed in claim 1, wherein the pneumatic actuator mounting bracket (12) is secured to the side of bottom air bellow mounting bracket which is connected to the axle assembly (1) of the vehicle by mechanical connectors.

5. The wheel straightening mechanism as claimed in claim 1, wherein the pneumatic actuators (6) is connected to pneumatic actuator mounting bracket (12) using fasteners.

6. The wheel straightening mechanism as claimed in claim 1, wherein the push rod end (7) is screwed to the push rod of the pneumatic actuators (6).

7. The wheel straightening mechanism as claimed in claim 1, wherein a suitable lock nut (20) is provided to lock the push rod ends (7) with the pneumatic actuators (6).

8. The wheel straightening mechanism as claimed in claim 1, wherein lock washers (15) are placed in between the lock nut (20) and the push rod ends (7) to prevent the loosening of the push rod ends (7) from the pneumatic actuator (6).

9. The wheel straightening mechanism as claimed in claim 1, wherein a pair of bearing bushes (21), made of a wear resistant material such as aluminium bronze or nylon or oilon coated steel tube, is inserted to the boss provided in the pneumatic actuators mounting brackets (12).

10. The wheel straightening mechanism as claimed in claim 1, wherein the push rod ends (7) has round shape at its forefront side and threaded portion in other side, wherein the threaded portion secures the push rod ends (7) with the pneumatic actuators (6).

11. The wheel straightening mechanism as claimed in claim 1, wherein, the straightening lever (8) is mounted with the wheel assembly (3) in a location where the vehicle steering arm is fitted.

12. The wheel straightening mechanism as claimed in claim 1, wherein the straightening mechanism is capable of being used as a steering stabilizer by providing an appropriate compressed air pressure to the pneumatic actuators (6) uses the pressure control valve.

13. The wheel straightening mechanism as claimed in claim 1, wherein said mechanism is operated during lifting the axle.