FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION {See Section 10; rule 13)
TITLE OF THE INVENTION A cabin Twist Arrester mechanism for Vehicles
APPLICANTS
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/S
Rajiv Pant & Mahesh Pardeshi
All Indian nationals
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.

A Cabin Twist Arrester mechanism for Vehicles
Field of invention:
The present invention is related to cabin tilting system of automobiles and more particularly it relates to a cabin twist arrester mechanism for vehicles which prevents cabin twist during tilt operation.
Background of invention:assis for light, medium and heavy commercial vehicles. The said cabin is
Generally the cabin is mounted on the ch mounted on chassis with a suitable isolation system in order to reduce the vibrations caused due to road roughness and drive train excited from transferring the said vibrations to said cabin. Typically the said cabin is mounted on three or four points on the said chassis. The said cabin is mounted on two points at front end and one or two points at rear end of said cabin.
The said cabins employs rubber bushes as front and shock absorbers at rear mounting points with latching arrangement. Typically during normal running of vehicle on any type of road, maximum resultant force experienced by the cabin mounts is ±3 to ±4G, where 1G = Reaction load at each cabin mounts in static condition.
Engine ancf drive train are mounted on chassis below the cabin, hence cabin tifting system is provided to access engine and drive train for serviceability.
The said cabin is tilted about the axis connecting front mounting points to facilitate accessibility of said engine and power train. The hydraulic assistance is employed in heavy vehicles for tilting the vehicle cabin. The said hydraulic system comprises one or two cylinders with a suitable pumping system. The lower end of said hydraulic cylinder is mounted on side face of chassis frame and upper end is mounted on cabin structure. The heavy cabins require two cylinders mounted on each side of said chassis frame.

The upper end of said hydraulic cylinder is mounted on cabin structure closer to the front cabin mountings. Thus during tilting operation the weight of cabin is supported on front cabin mounts and upper end mounting of said cylinder.
Eventually, the said front mounts of cabin experience much higher load during tilting thereby higher stiffness of rubber bushes becomes inevitable due to limited packaging space. The small deflection of said front mounts results in transfer of all pitch and rolls motion of chassis to cabin, leading to excessive vibration of cabin which reduces the ride and comfort to occupants in addition to the premature failure of cabin structure, electrical parts and creating noise inside the said cabin. The softer bushes are used to improve ride and comfort, but the use of softer bushes experiences the higher deformation during tilting of cabin due to high reaction force which leads to premature failure of rubber bush.
In the cabin mounted using single tilting cylinder, the top mounting point of cylininder being very close only to one of the front mounts which results in rotation of cabin around z axis during tilting of said cabin creating a mismatch between the striker and the latch. The improper latching may lead to a fatal accident. Also high force is experienced by mounting point close to said cylinder top point compared to the farthest point. Due to high force experienced by said mounting point close to cylinder top point causes different deflection in both the bushes and due to hysterics in said pivot bushes the cabin doesn't appear to realign after tilting back and appears inclined with respect to chassis.
Object of invention:
The main object of the present invention is to provide to a cabin twist arrester mechanism for vehicle for preventing cabin twist during tilt operation.
Another object of the present invention is to provide a cabin twist arrester mechanism for vehicle for preventing cabin twist during tilt operation which improves ride quality and Noise Vibration and Harshness (NVH) by making softer front cabin mounts.

Yet another object of the present invention is to provide a cabin twist arrester mechanism for vehicle for preventing cabin twist during tilt operation which shares the load coming on the front cabin mounts during tilting operation to prevent deflection of bushes thereby enabling to provide softer front mounts for improving the ride quality and NVH performance.
Statement of invention
A cabin twist arrester mechanism for vehicles comprises; at least two cab mounting bracket having pivot bush for mounting a tiltable cabin, a cam plate configured with an appropriate profile mounted on the front cabin structure , a follower member provided on said cab mounting bracket, the profile of said cam plate is configured in such a that the said cam plate is in contact with the said follower member only during tilting operation of cabin thereby load coming on said pivot bush during tilting operation is shared by said cam plate and follower member to prevent deflection of said pivot bush and misalignment of cabin tilting backward and avoiding the twisting of said cabin.
A cabin twist arrester mechanism for vehicles, in accordance with this invention, wherein said cam plate is detachably mounted on the vehicle front structure with the help of fastening means such as nut and bolts.
A cabin twist arrester mechanism for vehicles, in accordance with this invention, wherein said cam plate and follower arrangement is mounted on the side where single hydraulic cylinder for cab tilting is mounted on chassis member.
A cabin twist arrester mechanism for vehicles , in accordance with this invention, wherein said cam plate and follower arrangement is mounted on both side when said hydraulic cylinder for cab tilting is mounted on both side.
A cabin twist arrester mechanism for vehicles, in accordance with this invention, wherein said pivot bush having an extended member for mounting said follower member.
A cabin twist arrester mechanism for vehicles, in accordance with this invention, wherein said extended member is an integral part of said pivot bush.

A cabin twist arrester mechanism for vehicles, in accordance with this invention, wherein said follower member is a ball bearing or a steel sleeve arrangement with antifriction lining.
A cabin twist arrester mechanism for vehicles, in accordance with this invention, wherein said follower member is mounted on said extended member of said pivot bush of said cab mounting bracket provided on chassis member.
Brief description of invention:
In accordance with the present invention, a cabin twist arrestor mechanism for vehcile for preventing cabin twist during tilt operation comprises; at least two cab mounting bracket 3a having a pivot bush 3b for mounting a tiltable cabin 1, a cam plate 17 is configured with an appropriate profile mounted on the front cabin structure 1a , a follower member 16 provided on said cab mounting bracket 3a, the profile of said cam plate 17 is configured in such a that the cam plate 17 is in contact with the said follower member 16 only during tilting operation of cabin 1 thereby load coming on said pivot bush 3b during tilting operation is shared by said cam plate 17 and follower member 16 preventing the misalignment of said cabin 1 which is tilting backward to prevent the twisting of said cabin 1. Said cam plate 17 and said follower member 16 are free from each other in normal running of vehicle.
Brief description of drawings:
Figure -01 shows side view of the cabin mounted on chassis.
Figure -02 shows the side view of tilted cabin.
Figure -03 show the front isometric view of cabin.
Figure -04 shows the rear isometric view of cabin.
Figure -05 shows the rear view of cabin tilting initiated.
Figure -06 shows the top view of cabin tilting initiated.
Figure-07 shows the cam and follower arrangement in accordance with the
present invention.
Figure-08 shows cam mounting arrangement provided on cabin front structure.
Figure-09 shows a sectional veiw cam mounting arrangement at section E-E.

Ftgure-10 shows isometric view of follower arrangement provided on front
mounting bracket.
Figure-11 shows an Assembly of cabin twist arrester mechanism.
Figure-12 shows a sectional view of cabin twist arrester mechanism at EE.
Figure-13 shows the isometric view of cabin twist arrester mechanism.
Detailed description of invention:
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.
In accordance with the present invention, a cabin twist arrester mechanism for •vehicle for preventing cabin twist during tilt operation comprises; at least two cab mounting bracket 3a having a pivot bush 3b for mounting a tiltable cabin 1, a cam plate 17 is configured with an appropriate profile mounted on the front cabin structure 1a, a follower member 16 is provided on said cab mounting bracket 3a, the profile of said cam plate 17 is configured in such a that the cam plate 17 is in contact with the said follower member 16 only during tilting operation of cabin 1 thereby load coming on said pivot bush 3b during tilting operation is shared by said cam plate 17 and follower member 16 preventing the misalignment of cabin 1 which is tilting backward to prevent the twisting of said cabin.
Refering to figure-01 which shows side view of the cabin mounted on chassis frame. The said cabin 1 is mounted on said chassis frame 2 with the help of said front mounting bracket 3a provided at the front end of said chassis frame 2. The rear end of said cabin 1 is provided with shock absorber 5 to absorb the shock. Engine and drive train 6 are mounted on chassis below the cabin 1. The said cabin 1 is tilted about the axis connecting said front mounting brackets 3a on each side to facilitate accessibility of said engine and power train 6. The hydraulic cylinder 4 is employed for tilting the vehicle cabin 1. At normal cabin position, the centre of gravity 15 of said cabin is at the middle.
Refering to figure-02 which shows the side view of the tilted cabin. The said cabin is tilted with the help of said hydraulic cylinder 4. The said cabin 1 is tilted about

the axis connecting said front mounting brackets 3a. The said front mounting bracket 3a is provided on each side of chassis frame 2.
Refering to figure-03 and 06, which shows different views of tiltable cabin. The lower end of said hydraulic cylinder 4 is mounted on chassis frame 2 with the help of lower hydraulic cylinder mounting bracket 7 and upper end of said said hydraulic cylinder 4 is mounted to bottom of vehicle cabin 1 with the help of upper hydraulic cylinder mounting bracket 8. The cabin reaction forces 11, 12 are experienced at front mounting brackets 3a. The torque rod is disposed through said front cabin structure 1a and said pivot bush 3b at the front end for mounting tiltable cabin. The rear end of cabin is provided with rear mounting latch 9 and rear mounting striker 10. The cabin reaction forces 13, 14 are experienced at the said rear mounting latch 9 and rear mounting striker 10.
The lower end of said hydraulic cylinder is mounted on side face of chassis frame and upper end is mounted on cabin structure. The heavy cabins require two cylinders mounted on each side of said chassis frame.
The upper end of said hydraulic cylinder is mounted on cabin structure closer to the front cabin mounting bracket 3a. Thus during tilting operation the weight of cabin is supported on front cabin mounting bracket 3a and upper end mounting bracket 8 of said cylinder.
Refering to figure -07 to 13, the said cab mounting bracket 3a is provided with a pivot bush 3b for mounting a tiltable cabin 1. A cam plate 17 is configured with an appropriate profile and mounted on the front cabin structure 1a. A follower member 16 is provided on said cab mounting bracket 3a. The profile of said cam plate 17 is configured in such a that the said cam plate 17 is in contact with the said follower member 16 only during tilting operation of cabin 1 thereby load coming on said pivot bush 3b during tilting operation is shared by said cam plate 17 and follower member 16 to prevent the deflection of said pivot bush and the misalignment of cabin 1 tilting backward and avoiding the twisting of said cabin and prevents the accident.
The said cam plate 17 is detachably mounted on the front cabin structure 1a with the help of fastening means such as nut and bolts.

In case of single hydraulic cylinder cab tilting mechanism where the said cylinder is mounted on only one side of chassis member 2, the said cam plate 17 and follower member 16 arrangement is mounted on the same side of chassis member where single hydraulic cylinder for cab tilting is mounted.
In case of two hydraulic cylinder cab tilting mechanism where the said cylinders are mounted on both side of chassis member, the said cam plate 17 and follower member 16 arrangement is mounted on both the side of chassis member 2.
The said front cab mounting bracket 3a which is having a pivot bush 3b is mounted on front end of chasis member 2. The torsion rod is disposed through the said pivot bush 03b. The said torsion rod also passes through the front cabin mounting structure 1a for mounting the said tillable cabin 1 of vehicle.
The said follower member 16 is mounted on an extended member of said pivot bush 3b. The said extended member is an integral part of the said pivot bush 3b. The follower member 16 is mounted on extended member with the help of nut and bolts.
The said follower 16 is a ball bearing or a steel sleeve arrangement with antifriction lining provided therein and the said follower member 16 is mounted on said extended member of the said pivot bush 3b of the cab mounting bracket 3a which is provided on chassis member 02.
The said cam plate 17 comes in contact with said follower member 16 only during tilting operation of the said cabin 1.
The said cam plate 17 is in contact with the said fllower member 16 only during the tilting operation of said cabin 1 and said cam plate 17 and said follower member 16 are free from each other during normal running operation of vehicle, thus the load coming on said pivot bush 3b during tilting operation is shared by said cam plate 17 and follower member 16 and reduces the deflection of the said pivot bush 3b thereby enabling to prevent the misalignment of backward tilting if said cabin 1.
The load coming on said pivot bush 3b during tilting operation is shared by said cam plate 17 and follower member 16 which allows using the softer bushes for the

front mounting and thereby improving the ride, comfort and NVH performance of the vehicle.
The present invention enables to provide softer bushes for font mounting and improves the ride, comfort and NVH performance. The present invention enables to reduce 50 % forces experienced by the front mounting during cabin tilting operation. The reaction force on the front mount gets an alternate load path thereby reducing the force acting on the front mounts. The arrangement of present invention is provided closer to the upper end of said hydraulic tilting cylinder.
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 as they come within the scope of the invention as claimed or the equivalents thereof.

We claim
1. A cabin twist arrester mechanism for vehicles comprises; at least two cab mounting bracket having pivot bush for mounting a tiltable cabin, a cam plate configured with an appropriate profile mounted on the front cabin structure , a follower member provided on said cab mounting bracket, the profile of said cam plate is configured in such a that the said cam plate is in contact with the said follower member only during tilting operation of cabin thereby load coming on said pivot bush during tilting operation is shared by said cam plate and follower member to prevent deflection of said pivot bush and misalignment of cabin tilting backward and avoiding the twisting of said cabin.
2. A cabin twist arrester mechanism for vehicles as claimed in claim 1, wherein said cam plate is detachably mounted on the vehicle front structure with the help of fastening means such as nut and bolts.
3. A cabin twist arrester mechanism for vehicles as claimed in claim 1, wherein said cam plate and follower arrangement is mounted on the side where single hydraulic cylinder for cab tilting is mounted on chassis member.
4. A cabin twist arrester mechanism for vehicles as claimed in claim 1, wherein said cam plate and follower arrangement is mounted on both side when said hydraulic cylinder for cab tilting is mounted on both side.
5. A cabin twist arrester mechanism for vehicles as claimed in claim 1, wherein said pivot bush having an extended member for mounting said follower member.
6. A cabin twist arrester mechanism for vehicles as claimed in claim 1, wherein said extended member is an integral part of said pivot bush.
7. A cabin twist arrester mechanism for vehicles as claimed in claim 1, wherein said follower member is a ball bearing or a steel sleeve arrangement with antifriction lining.

8. A cabin twist arrester mechanism for vehicles as claimed in claim 1, wherein said follower member is mounted on said extended member of said pivot bush of said cab mounting bracket provided on chassis member.
9. A cabin twist arrester mechanism for vehicles as herein described with reference to accompanying drawings.