LIFT AXLE AIR SUSPENSION SYSTEM

Field of invention

The present invention relates to a suspension system and, more particularly to a tag lift axle air suspension system which lifts the tag axle from the road surface and held in a desired height from the road surface. This system is used in the heavy duty trucks and tractors as a tandem axle air suspension.

Background of invention

Suspension is term which is given to a system of spring, shock absorber and linkages that connects a vehicle to its wheels. It helps in contributing of the vehicle handling, vehicle ride and comport and braking for good active safety and driving pleasure. The suspension system protects the vehicle and cargo from damage and wear. In addition the suspension system suspends the vehicle chassis over the axle of the vehicle and absorbs axle movement caused by the tire experiencing pot holes, and uneven road surfaces. Axle movement occurs not only when tire experiences undulated road but also during acceleration, braking and during cornering. In these conditions, it is required that the suspension system provides stability to the vehicle by controlling movement. In order to increase the load carrying capacity of a heavy duty vehicle, tag axle (18) is added to the chassis frame (20).

FIG. 1 shows schematic of the multi-axle vehicle having tandem axles (24A) (i.e., two rear axle's configuration) with tag axle (18). Such tandem axles (24A) have one rear drive axle (23) and another is a dummy axle. The dummy axle is usually called as a tag axle (18). The tag axle (18) is added to the chassis frame (15) for increasing load carrying capacity of the vehicle. The tag axle (18) leads to reduce fuel efficiency and increase tire wear. Therefore, the tag axle (18) is lifted when the vehicle is unladen condition and/or partially loaded condition.

Numerous tag lift axle suspension systems have been designed and developed for lifting the tag axle (18) when the vehicle is operated in unladen and/or partial laden condition.

FIG.2 shows schematic of the multi-axle vehicle having tandem axles (24B) (i.e., two rear drive axles configuration). Such tandem axles (24B) have two rear drive axle (23). Such vehicles are especially operated in off-road application. Heavy duty commercial vehicles such as tippers and tractors should have more traction and load carrying capacity. Therefore, two rear drive axles (23) (tandem axles, 24B) are used at the rear side of the vehicle. Usually, in such configuration, the rear drive axle (23) is not being lifted.

Two types of lift axles are commercially available. They are self-steer axle and non-steer axle. In self-steer lift axle, single tire is used in each side of the axle; therefore, the load carrying capacity of the lift axle is limited, which is approximately equal to the front axle suspension of the vehicle. In the non-steer axle, single tire or twin tires are used in each side, of the axle. If twin tires are used, the axle load carrying capacity is approximately equal to the rear axle suspension of the vehicle. The auxiliary axle is fitted either front or rear side of the rear drive axle. Mostly, the non-steer axle is fitted in the chassis frame near to the rear axle; thereby tire wear can be minimized. If the auxiliary axle is fitted rear side of the drive axle, the axle is called as a tag axle suspention. If the auxiliary axle (i.e., lift axle) is fitted in the front side of the rear drive axle, it is called as pusher lift axle suspension.

The self steer lift axle is a parallelogram type air suspension, whereas, the non-steer lift axle is a trailing arm type suspension. The trailing arm system is literally that-a suspension arm is joined at the front to the chassis, allowing the rear to swing up and down. More clearly, the trailing arm air suspension comprises a trailing arm having one end is pivotally connected to the chassis frame through a frame bracket and another end is connected to the vehicle frame by an air spring. The trailing arm supports an axle which includes wheel. Road induced reaction forces acting on the wheels are controlled by the pivoting of the trailing arm in response to these forces being resisted by the air spring.

The conventional non-steer twin tire lift axle is usually used in the vehicles operated in haulage trucks and tipper. In these vehicles, many failures are observed in the conventional non-steer twin tire lift axle. The bush and wear washers used in the lever arm of the lift axle are experience a sever articulation load. Because, the conventional non-steer twin tire lift axle suspension does not have any link (or rod) to withstand the cornering load and articulation load. Therefore, entire load of the axle is acted on the wear washer. Therefore, the wear washers used in the lever arms are failed. Similarly, rubber bushes used in the shock absorbers pivot joints are also failed due to above said reason.

Moreover, the lever arm is subjected to a severe load in braking, acceleration and articulation conditions. During braking and acceleration the lever arm is subjected to an enormous compression load; therefore, the bushes are failed by creep (permanent set) very often.

Furthermore, a cylindrical tubular torque rod is used in the tandem rear axle air suspension. It is mainly to provide roll stability to the vehicles. However, it gives a lower ground clearance to the vehicle. The lower ground clearance leads to a major failure in the rear drive axle air suspension (i.e., rear air suspension) if the vehicle is operated in undulated road. Therefore, such vehicle having low ground clearance can't be operated in highly undulated road.

In addition, the commercial available lift axle can't be used as a rear drive axle air suspension. Therefore, a special attention is focused to design a lift axle air suspension such that it can be used as a rear drive air suspension in tandem axle (i.e., two rear axles).

Object of the invention

The main object of the present invention is to provide a tag lift axle air suspension system which lifts the tag axle from the road surface whenever required.

Another object of the present invention is to provide a tag lift axle air suspension system which can be used as a rear drive axle air suspension.

Another object of the present invention is to provide a tag lift axle air suspension system, which should increase fuel efficiency of the vehicle.

Another object of the present invention is to provide a tag lift axle air suspension system, which should extend the life of tire by reducing wear.

Another object of the present invention is to provide a tag lift axle air suspension system, which should withstand dynamic loads and shocks.

Another object of the present invention is to provide a tag lift axle air suspension system, which should be manufactured easily and inexpensive.

Yet another object of the present invention is to provide a tag lift axle air suspension system, having non-lubricated pivot joints.

Yet another object of the present invention is to provide a tag lift axle air suspension system, which is highly reliable and retrofittably mountable in the vehicle.

Yet another object of the present invention is to provide a tag lift axle air suspension system, which should improve ride and handling of the vehicle.

Summary of the invention

The present invention which achieves the objectives relates to a tag lift axle air suspension system having a pair of lever arms, a pair of hanger brackets, a pair of axle seat assemblies, a pair of shock absorbers, a V rod assembly, a axle holding assembly, a pair of ride air springs a lift air spring, a bottom lift air spring bracket, a torque plate, two rubber bushes, a pair of top air spring brackets, a axle lift bracket, and a pneumatic control system. The hanger bracket is securely attached with the chassis frame by bolts and nuts. The rubber bush is inserted in the pivotal hole provided in the lever arm.

One end of the lever arm is pivotally connected to the hanger bracket and other end of the lever arm is connected with the ride air spring, attached with the top air spring bracket.

The top air spring bracket is securely attached with the chassis frame. The axle seat assembly is pivotally connected to the lever arm through a non-lubricated bush. The tag axle is clamped with the axle holding assembly which consists of axle housing bracket and axle clamping bracket using the U bolts.

The V rod assembly is pivotally connected in between the cross member which is attached in between the side of the chassis frame and the axle holding assembly. The V rod assembly, lever arms and axle holding assembly together ensures a vertical movement of the axle with limited rolling angle when the vehicle is operated in undulated roads; so that angle between propeller shaft of the vehicle and the rear drive axle is maintained with in a required angle. It minimizes the pinion gear failure of differential gear box if the system is used in the rear drive axle. A torque plate is connected in between the lever arms which increases roll stability of the vehicle. A shock absorber is pivotally connected in between the axle seat assembly and the chassis frame.

A lift air spring is interposed in between the bottom lift air spring bracket attached with cross member of the chassis frame and the axle lift bracket attached with the axle holding assembly attached with the tag axle. During normal operation of the vehicle, the ride air springs are inflated and maintained a constant ride height using the pneumatic control system. During unladen condition, the ride air springs are deflated and the lift air spring is inflated using the pneumatic control system. Therefore, the lift air spring is expanded and the tag axle is lifted from the road surface at a required height.

Brief description of drawings

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.

FIG.l shows schematic of the multi-axle vehicle having tandem rear axles (24A), in which a drive axle (23) and a tag lift (18) axle, in accordance to prior art.

FIG.2 shows schematic of the multi-axle vehicle having tandem rear axles (24B), in which both the rear axles are drive axle, in accordance to prior art.

FIG.3 shows an assembled model of a lift axle air suspension system (1) fitted in a chassis frame (15) of a multi axle vehicle, in accordance to the present invention.

FIG.4 shows the details of the lift axle air suspension system (1), in accordance with an exemplary embodiment of the present invention.

FIG.5 illustrates the hanger bracket (3), in accordance with the embodiment of the present invention.

FIG.6 illustrates the lever arm (2), in accordance with an exemplary embodiment of the present invention.

FIG.7 illustrates the rubber bush (12), in accordance with an exemplary embodiment of the present invention.

FIG.8 illustrates the steel sleeve bush (13), in accordance with an exemplary embodiment of the present invention.

FIG.9 illustrates the axle seat assembly (4), in accordance with the embodiment of the present invention.

FIG. 10 illustrates the axle holding assembly (7), in accordance with the embodiment of the present invention.

FIG. 11 illustrates V rod assembly (6), in accordance with the embodiment of the present invention.

FIG. 12 illustrates the bottom lift air spring bracket (10), in accordance with the embodiment of the present invention.

FIG. 13 illustrates the axle lift bracket (14), in accordance with the embodiment of the present invention.

FIG. 14 illustrates torque plate (11) of the air suspension system, in accordance with an exemplary embodiment of the present invention.

FIG. 15 illustrates the tag lift axle air suspension system in a multi- axle vehicle having tandem axles (24A), in accordance to the present invention.

FIG. 16 shows the details of the tag axle air suspension system (1) used as tandem axles (24B) with two rear drive axles (23), in accordance to the present invention.

Detailed description of the invention

The present invention relates to tag lift axle air suspension system which lifts the tag axle from the road surface and held in a desired height from the road surface. The present utilizes a pair of ride air springs and a lift air spring to lift and held the tag axle from the road surface.

FIG. 3 shows an assembled model of the tag lift axle air suspension system (1) fitted in a chassis frame (15) of a multi axle vehicle, in accordance with an exemplary embodiment of the present invention. The tag lift air axle suspension system (1) is designed especially for the heavy duty vehicle having tandem axles (24A) (i.e., one rear drive axle (23) and a tag axle (18); such that the load which acts on the rear side of the vehicle is equally distributed to both the rear drive axle (23) and tag axle (18).

FIG. 4 illustrates the details of the tag lift axle air suspension system (1). The lift axle mechanism (1) comprises mechanical linkages lever arms (2) and V rod assembly (6) and air springs (8, 9) which are attached to the vehicle's chassis frame (15) and vehicle's tag axle (18). The tag lift axle air suspension system (1) consists of a pair of lever arms (2), a pair of hanger brackets (3), a pair of ride air springs (8), a pair of spring seat assembly (4), a bottom lift spring mounting bracket (10), a V rod assembly (6), a lift air spring (9), a axle lift bracket(14), a axle housing assembly (7) two rubber bushes (12), a torque plate (11), a pair of shock absorbers (5), a pair of top air spring mounting brackets (-13) and a pneumatic control system.

The lever arms (2) pivotally connected with the hanger brackets (3) attached to the chassis frame (15), and the torque plate (11) is rigidly connected in between both the lever arms (2). The center of lever arm (2) is pivotally connected with an axle seat assembly (7) in which the tag axle (18) is placed. The V rod assembly (6) is connected in between the cross member (22A) connected with the chassis frame (15) and axle holding assembly (7) attached with the tag axle (18). The ride air springs (8) are interposed in between the tail ends of the lever arms (2) and top air spring mounting brackets (13) connected to the chassis frame (15). The lift air spring (9) is attached in between the bottom lift air spring bracket attached with cross member (22A) of chassis frame (15) and the axle lift bracket attached with the axle holding bracket. The ride air springs (8) are deflated and lift air spring (9) is inflated using a pneumatic control system, such that the tag axle (18) is lifted from the road surface and held in a desired height from the road surface.

FIG.5 illustrates the details of the hanger bracket (3), in accordance to the present invention. The hanger brackets (3) are fitted to the chassis frame (15) of the vehicle by fastening means such as bolts and nuts and extended downwardly therefrom. A pivot hole (16) is provided in the hanger bracket (3) which is provided for connecting the lever arm (2) by the pivot bolts (25) and nuts. The hanger bracket (3) is designed such that it withstands all the loads experience in the tag axle (18).

FIG.6 illustrates the details of the lever arm (2), in accordance to the present invention.

The lever arm (2) is made of casting process. One end of the lever arm has an eye pivot hole (16) in which a rubber bush (12) is inserted tightly. After inserting the rubber bush (12), this end is pivotally connected to the hanger bracket (3) using a pivot bolt (25) and nut. Other end of the lever arm has a flat portion where a pair of holes (26) is provided which is used to attach the ride air springs (8) and the torque plates (11).

In order to connect the axle to the lever arm (2) pivotally, an eye (27) (pivot hole) is provided near to the middle of the lever arm (2) where a sleeve bush (28) is inserted tightly.

FIG.7 shows the rubber bush (12) of the tag lift axle air suspension system (1), in accordance to the present invention. The rubber bush (12) consists of rubber (29) and a visconite tube (30). The rubber (29) is embedded on the visconite tube (30). A special attention is provided to the design of the rubber bush (12). The rubber bush (12) is designed with side chamfers (31) (which are beveled edges). In addition, a groove (32) is also provided at the center of the outer surface of the rubber bush (12). The side chamfers (31) and grooves (32) are used to allow the rubber bush (12) to compress radically and expand side ward when the rubber bush (12) experiences load.

FIG.8 shows the schematic view of the sleeve bush (28), in accordance to the present invention. As it carries all the loads acting on the tag axle (18), a special attention is given in the design of the sleeve bush (28). Especially, a non-lubricate pivot joint is designed. It is preferably made of a wear and abrasive resistance materials and high bearing capacity. In the present invention, it is made of visconite or nylon embedded steel tube. The visconite or nylon (33) is embedded in side of the steel tube (34).

Referring to FIG. 9, the axle seat assembly (4) is made of casting process or austenite ductile irons (ADI) process. It is used to hold the tag axle (18). It is pivotally connected with the lever arm (2). The axle seat assembly (4) consists of an axle seat bracket (35), a C bracket (43), a pair of U bolts (36), a pivot bolt (37), a lock nut (38), a lock washer (39) and a pair of lock bolts (40). The axle seat bracket (35) has a rectangular slot (41) with four U bolt holes (42), where the tag axle (18) is placed and clamped with the C bracket (43), using the U bolts (36). It has a pair of legs (44) where a pivot hole (45), is provided which is used to pivot the axle seat bracket (35) with the lever arm (2) by the pivot bolt (37).

The pivot bolt (37) acts in the lift axle air suspension as a fulcrum about which the tag axle (18) is freely rotated when the lift axle suspension system (1) experiences undulated road. A pair of lock bolts and nuts (40) are used to prevents the rotation of the pivot bolt (37) and maintain a clearance in between the wear washers and axle seat bracket (35). In addition, a pivot hole (46) is provided in the axle seat bracket (35) adjoining to the U bolt hole (42). It is used to connect the shock absorber (5) pivotally. In order to lock the pivot bolt (37), a lock washer (39) and lock nut (38) is used.

FIG. 10 shows the axle holding assembly (7), in accordance with an exemplary embodiment of the present invention. It comprises an axle holding bracket (47), an axle clamping bracket (48) a pair of U bolts and nuts (49). The axle holding bracket (47) and axle clamping bracket (48) are used to hold the tag axle (18) rigidly. The axle clamping bracket (48) is a simple U shaped plate. These brackets are connected to the tag axle (18) and using the U bolts and nuts (49). The axle holding bracket (47) has multiples of holes (50) at the top side in which the axle lift bracket (14) is securely attached with the V rod assembly (6).

FIG. 11 illustrates the V rod assembly (6). The V rod assembly (6) consists of a V rod (51); a pair of upper V rod mounting brackets (52), a lower V rod mounting bracket (53), and three bar pins rubber bushings (54). The V rod has two upper eyes (55) and one lower eye (56). In all the eyes (55, 56), the bar pin rubber bushings (54) are tightly inserted. Upper eyes (55) of the V rod (51) are pivotally connected with the upper V rod mounting brackets (52) using bolts and nuts. The lower eye (56) of the V rod (51) is pivotally connected with the lower V rod mounting bracket (53) using bolts and nuts. The lower V rod mounting bracket (53) is securely connected with the axle holding bracket (47) attached to the tag axle (18), by bolts and nuts. The upper V rod mounting brackets (52) are securely attached with the cross member (22A) of the chassis frame (15) by bolts and nuts.

The V rod assembly (6) provides a lateral stability to the suspension system. In addition, the V rod assembly (6) is also used to form a parallelogram linkage mechanism in the lift axle air suspension system (1). In the modular lift axle air suspension system (1), the parallelogram linkage mechanism is formed by the combination of the hanger bracket (3), lever arm (2), V rod assembly (6), and axle seats assembly (4). The parallelogram linkage mechanism controls the upward and downward movement of the tag axle (18) with respective the chassis frame (15). More clearly, the parallelogram action of the suspension permits the tag axle (18) to freely pivot in the fore and apt direction as it deflects (moves) vertically with respective the chassis frame (15). It also ensures the tag axle (18) or rear drive axle (23) in vertical motion with limited turning angle (i.e., rolling angle) when the suspension system experiences undulated road.

FIG. 12 illustrates the bottom lift air spring bracket (10), in accordance to the present invention. The bottom lift air spring bracket is an L shape bent plate bracket (60). The bottom lift air spring bracket (10) have multiples of holes (57) which are used to connect the bottom lift air spring bracket (10)with the cross member (22B) of the chassis frame (15) by fastening means. In addition, a pair of holes (58) in the bottom side of the bracket is provided in which the lift air spring (9) is attached. In order to strengthen the bottom lift air spring bracket (10), three square section stiffener tubes (59) are welded with the L shaped plate (60). Furthermore, to avoid . bending of the L shaped plate (60), two additional stiffeners plates (67) are welded with both sides of the bottom lift air spring bracket (10).

FIG. 13 illustrates the axle lift bracket (14), in accordance to the present invention. It is attached with the axle holding bracket (7) attached with the tag axle (1) by U bolts and nuts (49). It consists of Z shaped sheet metal plate (61) and stiffener plates (62). The stiffener plates (62) are welded on the Z shaped plate (61). It has a pair of holes (64) in which the top end of the lift air spring (9) is attached.

FIG. 14 illustrates the torque plate (11), in accordance to the present invention. It consists of a flat plate (63) and hat section plate (64). They are welded together to make a rectangular box section as illustrated in FIG. 14. The rectangular box section is designed to maintain a large ground clearance of the suspension system. In addition, it is specially designed to prevent roll over and achieve roll stability (i.e., ability to resist roll over during use) and high level of safety. The torque plate (11) is connected in between the trail end of lever arms (2).

The ride air springs (8) are securely interposed in between the top air springs bracket (13) attached with the chassis frame (15) and the tail end of lever arm (2). After assembled the lift axle air suspension (1) with the chassis frame (15), compressed air is supplied to the ride air springs (8) using the pneumatic control system. The pneumatic control system is not the part of present invention. It maintains a required constant height in the ride air springs (8). In order to lift the tag axle (18), the ride air springs (8) are deflated and lift air spring (9) is inflated. When compressed air is entered in to the lift air spring (9), the lift air spring (9) expands; therefore, the tag axle (18) is lifted from the road surface. The lift air spring (9) holds the tag axle (18) at a desired height from the road surface.

In the lift axle suspension having twin tires, two lift air springs are usually used to lift the axle. In addition, the lift air springs are mounted along with the lever arms and interposed (i.e., packaged) within the hanger brackets. Whereas, in the present invention, only one lift air spring (9) is used to lift the tag axle (18) having twin tire (65). In addition, in the present lift axle system, the lift air spring (9) is located at the center of the chassis frame (i.e., in between the side member of the chassis frame) and it is interposed in between the bottom lift air spring bracket (10) and axle lift bracket (14) which is directly connected with the tag axle (18). It assists to easy accessibility of the lift air spring (9) and reduces the lift force required to lift the axle. The tag lift axle air suspension, according to the present invention, can be used as a rear drive axle air suspension for the bus and heavy duty trucks and tractors.

FIG. 15 illustrates the tag lift axle air suspension system (1) used as a rear air suspension in a multi-axles vehicle having tandem axles (24A) (i.e., first one is drive axle and another is tag lift axle) suspension. In which, first one is a rear drive axle (23) and another is a tag axle (18) which configuration of tandem rear axles suspension (24A) is used in the heavy duty vehicle. In order to build such rear air suspension systems (24A), all the components, except the axle lifting system (which includes lift air spring (9), axle lift bracket (14), and bottom air spring bracket (10)) are attached with the drive axle (23).

The lever arm (2), hanger bracket (3), axle seat assembly (4), shack absorber (5), V rod assembly (6), ride air spring (8), torque plate (11), top air spring bracket (13), used in the lift axle air suspension system (1) are assembled with the rear drive axle (23). Thereby, manufacturing cost and service cost are reduced. Similarly, validation time and cost of the axle is also reduced. Such a way, the production cost of the vehicle is reduced considerably.

Another unique of the present invention is the parallelogram mechanism used in the suspension. In the present lift axle air suspension system (1), twin tires (65) are used in each side of the tag axle (18). Usually, the parallelogram mechanism is used in a self-steer lift axle suspension, having single tire in each side of the axle. It is mainly to achieve a constant self steer-ability by keeping a constant caster angle in the steerable axle. The parallelogram mechanism is used in the rear axle air suspension for maintaining a constant pinion angle or limiting pinion angle in the differential gear box. It minimizes the vibration in the driveline of the vehicle; thereby, the driveline failure (i.e., pinion failure in the diffential gear box) is minimized. .

FIG. 16 illustrates the details of the tag lift axle air suspension (1) used as a tandem axles (22B) air suspension (two rear drive axles), in accordance to the present invention. In which, the two rear .drive axles (23) are interconnected by a pneumatics control system.

The pneumatics control system maintains an equal load distribution in between both the rear drive axles (23). The pneumatics control system maintains a constant ride height of the vehicle (i.e., a constant chassis height from the road surface).

Another advantage of the suspension is the design of the pivot joint which is used to pivot the axle seat assembly (4). In the conventional rear air suspension, a conventional rubber bush (i.e., rubber is bonded or embedded with a nylon tube or steel tube) is used. As the entire normal vertical load of the axle is acted on the single rubber bush, it fails frequently by permanent set (i.e., creep failure). The present invention provides a new design of the pivot bush, instead of the rubber bush, a heavy duty non-lubricated nylon or vasconite bonded steel bush is used.

Yet another advantage of the present invention is the use of less packaging area to mount the lift axle air suspension system (1) in the chassis frame (15). As the lift air spring (9) is packaged with the chassis frame (15), the suspension system can be fit in the tractor vehicle which has limited package area at the rear end of the vehicle.

The present invention can be used in the vehicle having single rear drive axle as well as tandem rear axles (i.e., two rear axles 24A) in which the tag axle can be lifted if the present lift system is fitted in the tag axle.

According to the present invention, the torque plate (11) is connected between the both lever arms (2) at tail end. The torque plate (11) is used to increase the roll stability of the air suspension. Therefore, anti-roll bar is not required in the air suspension. Minimum ground clearance is major concern in the design of tag lift axle (1) as well as rear drive axle (23) air suspension. In the present design, the roll rate of the torque plate (11) is varied by changing the width of the torque plate (11) without affecting the minimum ground clearance required for the vehicle.

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We Claim:

1. A lift axle air suspension system (1), comprising:

a chassis frame (15), a pair of hanger brackets (3) attached with the side members of the chassis frame (15), a pair of lever arms (2) pivotally attached with the hanger bracket (3) and a torque plate (11) clamped in between the lever arms (2) at the tail ends of the lever arms (2);

a tag axle (18) clamped with the an axle holding assembly (7) which connects the tail end of the lever arms (2) with the chassis frame (15) through a pair of shock absorbers (5); and a V rod assembly (6) pivotally connected in between the connecting ends of the cross member (22A) of the chassis frame (15) and the axle holding assembly (7);
wherein a pair of ride air spring (8) are interposed in between the chassis frame (15) and the tail end of the lever arms (2); and a lift air spring (9) is interposed in between the cross member (22B) connecting the chassis frame (15) and the axle holding assembly (7), said ride air springs and the lift air spring are actuated to lift and held the tag axle (18) from the road surface.

2. The lift axle air suspension system as claimed 1, wherein said lift air spring (9) is connected through a bottom lift air spring bracket (10) attached with the side members of the chassis frame (15).

3. The lift axle air suspension system as claimed 1, wherein said a pair of lever arms (2) are pivotally attached with the hanger brackets (3) and the tail ends are connected with the ride air springs (8).

4. The lift axle air suspension system as claimed 1, wherein said a tag axle (18) is clamped with the axle seat assemblies (4) which are pivotally attached with the lever arms (2) using a pair of pivot bolts (37) and a non-lubricated bushes made of nylon or visconite embedded steel tube (30).

5. The lift axle air suspension system as claimed 1, wherein said a torque plate (11) is a hat section shaped plate or a rectangular hollow section and is made of welding the hat shaped plate with a flat plate and is clamped in between both the lever arms (2) at the tail ends.

6. The lift axle air suspension system as claimed 1, wherein said ride air spring (8) are attached in between the top air bellows mounting bracket (13) attached to the chassis frame (15) and the tail ends of the lever arms (2).

7. The lift axle air suspension system as claimed 1, wherein said the lift air springs (9) are interposed in between the bottom lift air spring (10) attached with the side chassis member of the chassis frame (15) and the axle lift bracket (14) attached with the axle holding bracket (47).

8. The lift axle air suspension system as claimed 1, wherein said the V rod assembly (7) is pivotally connected in between the cross member (22A) of the vehicle and the axle holding assembly (7).

9. The lift axle air suspension system as claimed in claim 1, a bottom lift air spring bracket (10) attached with the side member of the chassis frame (15) and cross member (22B) of the chassis frame (15).

10. A tandem axle suspension and a rear drive suspension having a lift axle air suspension system as claimed in the preceding claims.

11. An automotive vehicle having a lift axle air suspension system as claimed in the preceding claims.