FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION Adjustable gear shift link mechanism for Manual transmissions
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
INVENTORS
Mr .Anand Damami, Mr. Sandeep Soni & Mr. Deepak Nale
All 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 describes the invention and the manner in which it is
performed.

Field of Invention: -
This invention relates to the adjustment of the gear lever of an automotive transmission. More particularly it relates to adjusting the gear shift lever in "X" direction for centralizing the gear lever with respect to the console cut out and adjusting the shift link mechanism in "Z" direction to ensure the gear lever in vertical position
Background of Invention:-
During the assembly build of the gearbox on vehicle for one of the new projects, following concerns were observed that the gear shift lever is not centralized within the console cutout on most of the vehicles getting built and the gear shift lever is not perpendicular to the console cutout and seen tilted towards front or rear. These problems are due to limitations on achieving the tighter tolerances on Chassis, BIW, rubber mountings thus leading to the variations in "X" & "Z" directions and results into inadequate clearances. Dynamic movement of the power train during various drive modes further worsens the situation. This results into poor ergonomic hand reach hence discomfort to the driver while shifting gears from Neutral to any position
A detailed study showed that there were many such incidences per thousand vehicles that would result into de - centralization of the gear shift lever from economically defined location causing discomfort to the passenger permanently, as it cannot be fixed afterwards also.
Objects of the invention :-
The main object of this invention is to obviate above drawbacks.
Another object is to provide flexibility for adjusting the gear shift lever to ensure the equalized
clearances in shifted condition with console cut out without compromising the gear shift quality

Summary of Invention :-
The adjustable shift link mechanism provides flexibility to adjust the gear shift lever in forward (-X) or backward (+X) direction by approx. 7 mm, however can be increased further, if required to minimize the impact of the tolerance variation resulting from manufacturing constraints
The system can also be adjusted in upward (+Z) or downward (-Z) directions by approx. 7 mm, however can be increased further, if required to ensure that the gear shift lever is held in vertical position
Brief description of the drawing :-
Fig 1. shows the isometric view of the adjustable shift link mechanism Fig. 2 shows the plan view of the adjustable shift link mechanism Fig. 3 shows the top view of the adjustable shift link mechanism
Summary of Invention :-
Accordingly the present invention discloses an adjustable gear shift link mechanism for manual
transmissions comprising
at least one extension arm or remote shift arm (1) securely connected to the gearbox;
at least one selector shifter shaft (2) of the gear shifting unit connected to the shifting yokes (4)
and (7);
at least one turnbuckle arrangement comprises of u-clamp arrangements (8) and (14)_connected
to the gear shifter unit on one end and gear shift lever (17) on the other end;
at least one Left Hand thread housing (9)_and at least one Right Hand thread housing (13) are
provided on said turnbuckle arrangement to facilitate the change in the length of said gear shift
link and securing the changed length by fastening means;
at least one shift block (15) securely tightened to said extension arm (1) by fastening means is
configured for adjusting the length of said turnbuckle assembly;

at least one support bush (21) securely fixed to the extension arm support bracket (23) by fastening means is configured for securely guiding the rear support of the extension arm (1) to facilitate the change in the vertical direction or height of said gear shift link and securing the changed height by fastening means; and
at least one gear shift knob (19) securely fixed on the gear shift lever (17) by fastrening means with lock nut 18. there is a provision for movement of the gear shift knob 19 in "Z" direction by approx. 10 mm, the lock nut 18 shall be re-tightened to the designed torque after adjustment of the height.
Detailed description of the invention :-
According to the latest trends in automotive industries, the aesthetic appearance of the vehicle interiors is of prime importance. To fulfill this requirement the console cutout size is kept to bare minimum to accommodate the various positions of the gear shift lever
It is observed in most of the cases that due to manufacturing constraints / limitations on chassis, BIW, rubber mountings and other related parts, the combined tolerances leads to decentralisation of the gear shift lever with respect to center of console cutout.
So, adjustments are required to be done on vehicle to take care of excessive power train tolerance stack variation in "X" & "Z" directions with reference to BIW ensure the design intent gear shift knob position for ergonomic hand reach without compromising the gear shift quality
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. 2 shows the adjustable shift link mechanism in its operating direction. 1 is extension arm or remote shift arm which is securely connected to the gearbox. 2 is the selector shifter shaft of the gear shifting unit which is connected to the shifting yokes 4 & 7. The turnbuckle arrangement comprises of u-clamp units 8 and 14 connected to the gear shifter unit on one end and gear shift

lever 17 on the other end. The turnbuckle arrangement is having Left Hand thread housing 9 and Right Hand thread housing 13 to facilitate the change in the length of the shift link in either "+X" or "-X" directions and securing the changed length by tightening the lock nuts 10 and 12 respectively.
The shift block 15 is securely tightened to extension arm 1 with the help of nylock nuts 16 and 20 respectively, the shift block 15 is having oblong slots and can be moved back and forth in the extension arm 1 within the guided slot by the desired amount. The process of change in the length of the turnbuckle assembly 8 to 14 and movement of shift block 15 has to be performed simultaneously, subsequently the nylock nuts 16 and 20 needs to be tightened.
The rear support of the extension arm 1 is securely guided in the support bush 21 and the support bush 21 is securely fixed to the extension arm support bracket 23 by 2 lock nuts above and below the support bracket 23. The support bush 21 having full depth thread to allow for movement in "+Z" or "-Z" direction. After the desired movement is achieved the lock nuts shall be tightened to the designed torque for securing the further movement
The gear shift knob 19 is securely fixed on the gear shift lever 17 by with lock nut 18. there is a provision for movement of the gear shift knob 19 in "Z" direction by approx. 10 mm, the lock nut 18 shall be re-tightened to the designed torque after adjustment of the height
The whole shift link mechanism has been designed and analysed for ensuring 2nd order engine frequency of 150 Hz for minimized vibrations and carrying 20 kg of shift force at the gear shift knob.
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. An adjustable gear shift link mechanism for manual transmissions comprising
at least one extension arm or remote shift arm (1) securely connected to the gearbox;
at least one selector shifter shaft (2) of the gear shifting unit connected to the shifting yokes (4) and (7);
at least one turnbuckle arrangement comprises of u-clamp arrangements (8) and (14)_connected to the gear shifter unit on one end and gear shift lever (17) on the other end;
at least one Left Hand thread housing (9)_and at least one Right Hand thread housing (13) are provided on said turnbuckle arrangement to facilitate the change in the length of said gear shift link and securing the changed length by fastening means;
at least one shift block (15) securely tightened to said extension arm (1) by fastening means is configured for adjusting the length of said turnbuckle assembly;
at least one support bush (21) securely fixed to the extension arm support bracket (23) by fastening means is configured for securely guiding the rear support of the extension arm (1) to facilitate the change in the vertical direction or height of said gear shift link and securing the changed height by fastening means; and
at least one gear shift knob (19) securely fixed on the gear shift lever (17) by fastrening means with lock nut 18. there is a provision for movement of the gear shift knob 19 in "Z" direction by approx. 10 mm, the lock nut 18 shall be re-tightened to the designed torque after adjustment of the height.
2. The gear shift mechanism as claimed in claim 1 wherein said Left Hand thread housing (9)_and Right Hand thread housing (13) are provided on said turnbuckle arrangement to facilitate the change in the length of the gear shift link in either "+X" or "-X" directions and securing the changed length by said fastening means by tightening lock nuts (10) and (12) respectively.
3. The gear shift mechanism as claimed in claim 1 wherein said shift block (15) having oblong slots and can be moved back and forth in the extension arm (1) within said guided slot, is

configured for securely tightening to said extension arm (1) by fastening means like nylock nuts (16) and (20) respectively.
4. The gear shift mechanism as claimed in claim 1 wherein the process of change in the length of said turnbuckle assembly comprising of parts (8) to (14) and movement of shift block (15) has to be performed simultaneously upon subsequently tightening the nylock nuts 16 and 20.
5. The gear shift mechanism as claimed in claim 1 wherein said support bush (21) having full depth thread to allow for movement in "+Z" or "-Z" direction is securely fixed to the extension arm support bracket (23) by fastening with 2 lock nuts above and below said support bracket (23) on adjustment of the desired movement in said "+Z" or "-Z" direction.
6. The gear shift mechanism as claimed in claim 1 wherein said gear shift knob {19) capable of adjusting in "Z" direction by approx. 10 mm is securely fixed on the gear shift lever (17) by lock nut (18).
7. The gear shift mechanism as claimed in claim 1 wherein said shift link mechanism is constituted for ensuring 2nd order engine frequency of 150 Hz for minimized vibrations and carrying 20 kg of shift force at the gear shift knob.
8. The adjustable gear shift link mechanism for manual transmissions substantially as herein described with reference to accompanying drawings.