FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Suspension Locking Mechanism
APPLICANT
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTOR
ASHISH PUROHIT, Indian national of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in
which it is to be performed

FIELD OF INVENTION:
The present invention generally relates to a suspension system for heavy commercial vehicles and more specifically to a suspension locking mechanism to provide a rigid connection between axle and the vehicle body.
BACKGROUND OF THE INVENTION
Heavy vehicles are commonly equipped with leaf spring type suspension for absorbing road shock and other vibration while providing a smooth ride to the vehicle. A suspension system is a flexible member placed between an axle and a frame of the vehicle and normally, always being in the action weather vehicle is moving or stationary. A locking of suspension system is desirable in such situation where the vehicle should behave as a single rigid body and to avoid the vibration of the device mounted above the load body due to flexibility of suspension system in the vehicle. Therefore, it is desirable to remove the flexibility effect from the suspension system. In order to achieve above requirement, a suspension system can be removed from the system and a rigid connection can be provided between the axle and a frame, but this kind of arrangement will spoil the vehicle basic nature of comfort ride and rolling, pitching etc. behavior during motion of the vehicle. Hence there is a need to provide a system to avoid the suspension effect when desired and to bring back the system when the vehicle is in moving condition. There is also a need to provide a system which is easy to operate and to lock the suspension during uneven road condition with respect to the vehicle frame.
OBJECT OF THE INVENTION
The main objective of the present invention is to obviate above mentioned drawbacks.
Another object of the present invention is to provide a mechanism for locking suspension system to provide a rigid connection between the axle and the vehicle body and to avoid suspension effect from the system.
Yet another object is to provide a suspension locking mechanism for heavy commercial vehicles to offer resistance against fluctuating force and to provide stability to the vehicle.
Yet another object of the present invention is to provide a mechanism to lock the suspension system when desired by the driver by using an ON and OFF switch provided in

the driver cabin and to unlock the suspension system when the vehicle is in moving condition.
Yet another object of the present invention is to lock the suspension for different position of axle or uneven road condition, with respect to the vehicle frame.
SUMMARY OF THE INVENTION
The present invention provides a mechanism for locking suspension system between axle and frame in heavy vehicles. The locking mechanism comprising a rack fixed to said axle at lower end and a slidable telescopic tube provided at upper end of said rack, said slidable telescopic tube is fixed to said frame at one end. The telescope tube reciprocates upon said rack in unlocked condition to avoid engagement with said pinion when said vehicle moves. A pinion with a slider link is slidably fixed with respect to said frame and actuated by an actuation means to engage or disengage said pinion with said rack. A positive locking mechanism with a cam based actuation means and spring loaded link is provided to engage or disengage said rack from said pinion.
According to another embodiment, the present invention provides a mechanism for locking suspension system between axle and frame in heavy vehicles. The locking mechanism comprising a rack with a curved teeth profile coupled to said frame at one end, other end of said rack being suspended freely. An actuation means is coupled to said rack by a hinge in between free end and fixed end to restrict movement. A pinion with curved teeth profiles is fixed to said axle. The actuation means is provided to engage or disengage said rack with said pinion, said actuation means coupled to said rack by coupling means. According to present invention, the suspension system is locked and unlocked by driver using an ON OFF switch provided in driver cabin.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side view of a typical heavy commercial vehicle with a suspension system.
FIG. 2 shows a perspective view of a typical suspension system of the heavy commercial
vehicle.
FIG. 3 shows a plane view of the locking mechanism when the rack and the pinion are in
engaged position according to present invention.

FIG. 4 shows a plane view of the locking mechanism when the rack and pinion is in
disengaged position, and lever link rotates in clockwise direction, according to present
invention.
FIG. 5 shows a plane view of the locking mechanism when the rack and the pinion are in
completely disengaged position, according to present invention.
FIG. 6 shows a plane view of the locking mechanism when the rack and the pinion are in
engaged position, according to another embodiment of the present invention.
FIG. 7 shows a plane view of the locking mechanism of FIG. 6, when the rack and the
pinion are in disengaged position, according to another embodiment of the present
invention.
FIG. 8a and 8b shows a side view and front view of the rack and pinion of FIG. 6, to
illustrate a curved teeth profile of rack and pinion, according to present invention.
FIG. 9, 10 and 10 illustrates an engagement of rack and pinion shown in FIG. 6, in three
different position of the axle, according to present invention.
DETAILED DESCRIPTION OF THE INVENTION
The embodiments herein provide a locking mechanism for suspension system in vehicles.
The locking mechanism includes a teethed links which provides a positive locking and stop the function of the suspension system in vehicles. The locking mechanism provides a rigid connection between the axle and frame of the vehicle. One end of each link is connected to the axle and frame of the vehicle and other end engage through the teeth, when teeth's are engaged the axle rigidly linked with the body act as a single entity and the force is transfer from body to ground or visa versa. When the links are disengaged the suspension comes in the force transfer path and offers flexibility in the system. The vehicle with the locked suspension system behaves as a rigid mass and offer resistance against the fluctuating force and provides stability to the vehicle. The actuation of the locking mechanism is controlled from the driver's cabin by using ON and OFF switch.
FIG. 1 and 2 shows a side view and perspective of a typical suspension system for heavy commercial vehicle. The commercial vehicle includes a suspension 1, tires 3, axle 2a and 2b, frame 4 along with a load body 4a and cab 4b. The suspension 1 is mounted on the frame 4 by using brackets la, lb, lc and Id. The brackets are mounted on the frame by using fasteners. The axle 2a and 2b is connected on the lower side of the leaf spring of the

suspension. The main function of the suspension system is to provide flexibility between the axle and the load body 4a.
FIG. 3 shows a plane view of the locking mechanism when the rack 5 and the pinion 7 are in engaged position according to present invention. The suspension locking mechanism is connected between the frame 4 and axle 2a or 2b. The locking mechanism comprising a rack 5 fixed to said axle 2a at lower end and a siidable telescopic tube 6 provided at upper end of said rack, said siidable telescopic tube 6 is fixed to said frame at one end. A pinion with a slider link is slidably fixed with respect to said frame and actuated by an actuation means to engage or disengage said pinion with said rack. A positive locking mechanism with a cam based actuation means and spring loaded link 9 is provided to engage or disengage said rack from said pinion.
According to present invention, the bracket profile 7a is provided on said pinion 7,.said bracket profile 7a projects out through a cut portion provided on said fixed bracket 7b. The telescope tube 6 reciprocates in vertical direction upon said rack 5 in unlocked condition to avoid engagement with said pinion 7 when said vehicle moves. The pinion 7 with slider link 11 reciprocates in horizontal direction in a slot provided in a fixed bracket 7b, said fixed bracket 7b is mounted on said frame by fasteners. The positive locking mechanism includes a lever link 8 pivoted on said frame 4 and above said fixed bracket 7b, one end of said lever link 8 reciprocates above said fixed bracket and in front of said projected bracket profile 7a. The other end of said lever link 8 is coupled to the cam based actuation means. The spring loaded link 9 pivoted above said fixed bracket 7b on said frame 4, one end of said spring loaded link 9 includes a flat inclined profile and arrives in contact with plane surface of said lever link 8 and other end comes in contact with end of said bracket profile 7a.
The actuation means includes a pneumatic actuator. The pneumatic actuator 11a is connected to said slider link 11, said pneumatic actuator 1 la is mounted on said frame 4 by fastening means. The pneumatic actuator 11 a is actuated during locking condition to push the slider link 11 which inturn pushes the pinion 7 in forward direction to engage the pinion 7 with the rack 5. Due to locking of said teeth, the relative movement between rack 5 and tube 6 stops. As the teeth's are locked the rack 5, pinion 7, bracket 7a, axle 2a and

frame 4 behave as a rigidly connected assembly. The suspension system is locked and unlocked by driver using an ON OFF switch provided in the driver cabin.
The lower end of rack 5 is connected to the axle 2a by using a bracket 5a. A ball joint Bl is provided to join the lower end of long teethed link with the axle 2a. The top end of the telescopic tube 6 is connected to the vehicle body 4a or frame 4. The ball joint B2 is provided to join the tube 6 and frame 4. Due to telescopic tube 6, the rack 5 has guided motion during the unlocking condition. When the vehicle moves, the telescopic tube 6 avoids the interference of rack 5 with adjacent components on the vehicle.
The pinion 7 exhibits a horizontal sliding motion within the fixed bracket 7b. The fixed bracket 7b is mounted on the frame 4 by fasteners. A slider link 11 is provided behind the pinion 7 to push the slider link 7 in forward direction during locking of the suspension system. The slider link 11 slides in the slot provided in the bracket 7b. The slider link 11 is actuated by the pneumatic actuator 1 la which is fixed on the frame 4 by fasteners or the like. The slider link 11 and pinion 7 have a planner contact with each other. The nature of joint between slider link 11 and the pneumatic actuator 11a is a pin type. During suspension locking mechanism the teeth's in the pinion 7 is engaged with the teeth's on the rack 5 to provide a rigid connection between the frame 4 and axle 2a.
According to present invention, a lever link 8 is pivoted on the frame 4 at pin joint PI, Said lever link 8 reciprocates in the same plane as that of the slider link 7. During disengagement of the rack 5 and the pinion 7, the lever link 8 comes in line contact with the extended portion 7a in the pinion 7. In order to actuation of lever link 8 a slot is cut on the upper portion of the said lever link 8 and a roller 8a rolls in the slot and rotate the link. The roller 8a is connected to said cam based actuation means. The cam based actuation means is a pneumatic actuator 8b. The pneumatic actuator 8b is inturn fixed to the frame 4.
FIG. 4 shows a plan view of the locking mechanism when the rack 5 and pinion 7 is in disengaged position, and lever link rotates in clockwise direction, according to present invention. FIG. 5 shows a plan view of the locking mechanism when the rack 5 and the pinion 7 are in completely disengaged position, according to present invention. During the disengagement operation the actuator 8b is actuated which in turn pushes the roller 8a. The

roller 8a rotates the lever link 8 in clockwise direction. The lower end of the lever link 8 pushes the extended portion 7a of the pinion 7 and disengages the link 5 and pinion 7. According to present invention, in addition to the above locking and unlocking mechanism of the suspension system, the spring loaded link 9 is provided. The prime function of the spring loaded link 9 is to ensure secondary locking of the pinion 7 and to avoid undesirable unlocking during failure of function of pneumatic actuator lib.
During suspension locking mechanism the pinion 7 is under a constant pressure of the actuator 11b, hence the pinion 7 will not come back to disengage the locking system. But in some cases because of the failure of the pneumatic actuator 11a the resisting force will be vanished and the pinion 7 may move back to unlock the suspension system, as a results the suspension system and hence whole firing operation will be spoiled or results in a dangerous situation. In order to prevent such as situation an additional spring loaded pivoted link 9 is provided which act as a stopper for the pinion 7, even if the pneumatic actuator 11a fails. During locking condition, the pinion 7 will be on its extreme left position as well as the lever link 8 will be on its left most position. In said position, the inclined flat surface of spring loaded link 9 will be in planner contact with the lever link 8 and its lower end will be touching back side of the extended portion 7a, in this situation pinion 7 can move back only after turning the spring loaded link 9, which will not turn due to contact with lever link 8 and secondary locking function. As a result, in adverse condition even if the actuator fails the slider will not move back and the suspension will be in locked state. Similarly, during unlocking operation, the link 8 rotates clockwise which pushes the extended portion 7a and give room for the spring loaded link 9 to rotate in clockwise direction. As the spring loaded link 9 can rotates it allows the pinion 7 to move back and unlocks the suspension system.
FIG. 6 shows a plan view of the locking mechanism when the rack and the pinion are in engaged position, according to another embodiment of the present invention. As shown in FIG. 6, the locking between the axle 2a and the frame 4 is provided through the engagement of rack 13 and pinion 20. The rack 13 and pinion 20 includes a straight teeth profile, wherein the teeth's are fabricated in a curve shape. The mechanism comprises a rack 13 with a curved teeth profile coupled to said frame at one end, other end of said rack being suspended freely. An actuation means is coupled to said rack by a hinge in between

free end and fixed end to restrict movement. A pinion 20 with curved teeth profiles is fixed to said axle 2a. The actuation means is provided to engage or disengage said rack with said pinion, said actuation means coupled to said rack by coupling means.
The rack 13 is connected to a bracket 14 by pivot joint P5 and other end is suspended freely. An intermediate link 15 is provided between said rack 13 and said bracket 16. The actuation means includes a pneumatic actuator. The pneumatic actuator 18 is bolted to a bracket 19 and mounted on said frame 4.The coupling means includes an intermediate link 15 provided between said rack 13 and said bracket 16 and a cylindrical bar type slider 17 is connected between said bracket 16 and said actuating means.
The pneumatic actuator 18 is actuated to reciprocate said rack 13 in forward and reverse direction to lock and unlock the suspension system of vehicle. The curved teeth profiles on said rack 13 and pinion 20 is provided to ensure engagement of rack 13 with pinion when the position or angle of said axle varies with respect to the ground during locking of suspension. The cylindrical bar type slider 17 and said intermediate link 15 is provided to transmit the actuation of said pneumatic actuator 18 to said rack 13. The actuation from the pneumatic actuator 18 to the link 13 is communicated through a cylindrical bar type slider 17 and an intermediate link 15 pneumatic actuator 18. One end of said intermediated link 15 is connected to plane surface of said rack 13 at pivot point P6 and other end is connected to said bracket 16 at pivot point P7. The intermediate link 15 converts the straight motion of said cylindrical slider 17 in to curved motion of link 13. During locking of suspension system the pneumatic actuator 18 pushes said cylindrical slider 17 and which ultimately pushes rack 13 with curved teeth profiles about said pivot point P5 and get engaged with the curved teeth profiles on pinion.
FIG. 7 shows a plan view of the locking mechanism of FIG. 6, when the rack 13 and the Dinion 20 are in disengaged position, according to another embodiment of the present invention. During unlocking condition the air supply to said pneumatic actuator 28 is stopped which ultimately pulls cylindrical slider 17 and hence rack 13 and disengages said ■ack 13 from said pinion 20.
FIG. 8a and 8b shows a side view and front view of the rack and pinion of FIG. 6. to llustrate a curved teeth profile of rack and pinion, according to present invention. The

reason for providing curve line teeth in both the mating parts is to ensure the engagement for ant articulated position of axle 2a with respect to frame 4. Preferably, locking operation will be performed on stationary vehicle but position of the axle is depend on the ground condition, it can be horizontal or in angled position from the ground. FIG. 9, 10 and 10 illustrates an engagement of rack and pinion shown in FIG. 6, in three different position of the axle, according to present invention.
ADVANTAGES
• The locking mechanism for suspension system according to present invention provides a rigid connection between the axle and the vehicle body and hence eliminates the suspension effect from the system.
• The locking mechanism offers resistance against the fluctuating force and provides stability to the vehicle.
• The locking mechanism can be easily locked and unlocked by the driver by using an ON and OFF switch provided in the driver's cabin.
• The locking mechanism for suspension system is provided such that to lock the lock the suspension in different position of the axle with respect to the vehicle frame.
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 mechanism for locking suspension system between axle and frame in heavy vehicles.
comprising;
a rack fixed to said axle at lower end and a slidable telescopic tube provided at upper end
of said rack;
said slidable telescopic tube is fixed to said frame at one end,
a pinion with a slider link slidably fixed with respect to said frame and actuated by an
actuation means to engage or disengage said pinion with said rack;
a positive locking mechanism with a cam based actuation means and spring loaded link 9
provided to engage or disengage said rack from said pinion.
2. The locking mechanism according to claim 1, wherein said telescope tube 6 reciprocates in vertical direction upon said rack 5 in unlocked condition when said vehicle moves.
3. The locking mechanism according to claim 1. wherein a bracket profile 7a is provided on said pinion 7, said bracket profile 7a projects out through an opening on said fixed bracket.
4. The locking mechanism according to claim 1, wherein said pinion 7 with slider link 11 reciprocates in horizontal direction in a slot provided in a fixed bracket 7b, said fixed bracket being mounted on said frame by fasteners.
5. The locking mechanism according to claim 1, wherein said positive locking mechanism includes a lever link 8 pivoted on said frame 4 and above said fixed bracket 7b, one end of said lever link 8 reciprocates above said fixed bracket and in front of said projected bracket profile 7a. other end of said lever link 8 is coupled to said cam based actuation means.
6. The locking mechanism according to claim 1, wherein said spring loaded link 9 pivoted above said fixed bracket 7b on said frame 4, one end of said spring loaded link 9 includes a flat inclined profile and arrives in contact with plane surface of said lever link and other end comes in contact with end of said bracket profile 7a.
7. The locking mechanism according to claim 1, wherein said actuation means is a pneumatic actuator or a hydraulic actuator or a mechanical actuator 1 la.

8. The locking mechanism according to claim 7. wherein said pneumatic actuator 1 la is connected to said slider link 11 and mounted on said frame 4 by fastening means.
9. The locking mechanism according to claim 7, wherein said pneumatic actuator 11a is actuated during locking condition to drive said slider link 11 which inturn drives said pinion 7 in forward direction to engage said rack 5 with said pinion 7. to stop the relative movement between said rack 5 and tube 6.

10. The locking mechanism according to claim 1. wherein said cam based actuation means is a pneumatic actuator or a hydraulic actuator or a mechanical actuator 8b.
11. The locking mechanism according to claim 10, wherein said pneumatic actuator 8b is actuated during unlocking condition which inturn rotates said lever link 8b in clockwise direction, lower end of said lever link 8 pushes said extended bracket 7a of said slider link 7 and disengages rack 5 and pinion 7.
12. The locking mechanism according to claim 5. wherein said lever link 8 reciprocates in same plane as that of the pinion 7 during unlocking of rack 5 and pinion 7.
13. The locking mechanism according to claim 5, wherein said lever link 8 forces said extended bracket 7a on said pinion 7 during unlocking operation to release said pinion 7 respectively.
14. The locking mechanism according to claim 6, wherein inclined flat surface of said spring loaded link 9 is in planner contact with said lever link 8 and its lower end touches back side of extended bracket 7a to ensure positive locking in locked condition.
15. The locking mechanism according to claim 1, wherein in unlocking condition said lever link 8 rotates in clockwise direction and drives said extended bracket 7a and give room for spring loaded link 9 to rotate in clockwise direction and allows pinion 7 to move back and unlock the suspension system.
16. The locking mechanism according to claim 1, wherein said suspension system is ■locked and unlocked by driver using an ON OFF switch provided in driver cabin.

17. A mechanism for locking suspension system between axle and frame in heavy
vehicles, comprising;
a rack 13 with a curved teeth profiles coupled to said frame at one end, other end of said
rack being suspended freely; and an actuation means is coupled to said rack by a hinge in
between free end and fixed end to restrict movement;
a pinion 20 with a curved teeth profiles fixed to said axle 2a;
said actuation means provided to engage or disengage said rack with said pinion, said
actuation means coupled to said rack by coupling means;
18. The locking mechanism according to claim 17, wherein said curved teeth profiles on said rack 13 and pinion 20 is provided to Jock said rack 13 with pinion 20 when the position or angle of said axle varies with respect to the ground.
19. The locking mechanism according to claim 17, wherein said rack is coupled to said frame by a bracket 14, said bracket 14 mounted on said frame 4 by fastening.
20. The locking mechanism according to claim 11, wherein said coupling means includes an intermediate link 15 provided between said rack 13 and said bracket 16 and a cylindrical bar type slider 17 is connected between said bracket 16 and said actuating means.
21. The locking mechanism according to claim 17, wherein said actuation means is a pneumatic actuator or a hydraulic actuator or a mechanical actuator which is bolted to said frame to lock and unlock the suspension system of vehicle.
22. The locking mechanism according to claim 20, wherein said cylindrical bar type slider 17 and said intermediate link 15 transmits the actuation of said pneumatic actuator 18 to said rack 13.
23. The locking mechanism according to claim 20, wherein said intermediate link 15 converts linear motion of said cylindrical slider 17 in to curved motion of rack 13.
24. The locking mechanism according to claim 17, wherein in locked condition said pneumatic actuator 18 pushes said cylindrical slider 17 and which ultimately pushes rack

13 with curved teeth profiles about said pivot point p5 and get engaged with the curved teeth profiles on pinion.
25. The locking mechanism according to claim 17, wherein during unlocking condition said pneumatic air supply to said pneumatic actuator 28 is stopped which draws cylindrical slider 17 and rack 13 to disengages said rack 13 from said pinion 20.