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 mechanism for transfer - case mode selection
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 Swichalappa Damami, Mr. Ashok Rudragoud Biradar, Mr. Deepak Kundlik Nale, Mr. Sangram Kesari Jena and Mr. Trimurthulu Tentu
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 describes the invention and the manner in which it is
performed.

Field of invention:
An All wheel drive vehicle can have a part time Pr full time transfer-case ( or Auxiliary Gear-box). In a part time transfer-case the driver has to select the mode in which the vehicle is to be driven. Mode selection has to bP effected by electrical means or mechanically by means of a linkage, depending on the type of transfer-case . This invention relates to the linkages used for mode selection of a Part time Mechanical Shift Transfer-case.
Background of Invention:
In a part-time mechanical shift transfer-case thei'e are 4 modes of operation wwasty 2H,4U.,"N sad 4L.ta> 2R vcsMe N^W&VS. befesN^& V&4 a- standard, near-whsd. drive, In 4H mode power is transferred from engine to all the four wheels of the vehicle. However there is no speed reduction occurring in the transfer-case. In N mode (spelled as neutral mode) there is no power transmission to any of the wheels. In 4L mode there is power transmission to ail the 4 wheels and there is speed reduction occurring in the transfer-case. Depending on the terrain which has to be traversed by the vehicle the driver makes selection of the appropriate mode. For rfiode selection a mechanical linkage is required. This is the topic of our invention.
A Mechanical shift transfer-case can operate in 4 Ixodes namely 2H, 4H, N and 4L mode. For mode selection a shaft (henceforth referred to as transfer-case shaft) which protrudes out of the transfer-case needs to be rotated-
Conventionally the motion of mode selection lev^r is in more than one plane. This is used to prevent direct shifting from high modes to low mode or neutral mode when the vehicle is in motion. Examples of this type of motion of mode selection lever are shown in Figure 12 (a) and (b).
For cost effectiveness the same transfer-case is used on a variety of vehicle platforms with a variety of engine-gearbox combinations. The relative position of the

mechanical shift transfer-case and ths driver seat mil be different for each combination. The vehicle may also be a Right hand drive or a Left hand drive depending on the country in which it is being sold.
As seen above there are variety of combinations in which the same transfer-case is used. This requires an unique linkage for each combination. This adds to complexity and cost. The requirement is for such a linkage which can be used on all the combinations possible. At the same time there is a constraint that there should be no modifications in the gearbox or transfer-case.
Objectives of the invention:
The main objective of the invention is to provide an in-line mode selection shifting mechanism.
Another objective of this invention is to provide a compact and safe linkage for transfer-case mode selection.
Yet another objective of the invention is to provide simplicity in design, adaptability to various engine-gearbox-vehicle combinations, low cost of manufacture and ease of assembly.
Summary of the invention:
Mechanical shift transfer-case mode selection linkage generally comprises of two shift levers. The lever actuated by the driver (henceforth referred to as mode selection lever) is mounted on a bracket (henceforth referred to as upper bracket) for pivotal movement between the four positions f 2H,4H,N and 4.L modes), and the other (henceforth referred to as lower link) is rigidly fastened to the transfer-case shaft. As a consequence of being rigidly mounted on the shaft the lower link will always move in a plane. The travel of mode selection lever can be in one plane (referred to as inline motion) or in more than one plane. This invention uses inline motion for the mode selection lever. This is shown in Figure 11.

Inline arrangement is preferred as it consumes least space among all the arrangements possible. However it introduces complexity from safety point of view which is not the case in the arrangements shown in Figure 12 (a) and (b). This safety concern has been addressed in the proposed invention and the same is explained later on.
The upper bracket is mounted on the BIW of the vehicle. The upper bracket serves the dual purpose of providing a pivot for the lever as well as providing a cable anchoring surface.
Motion and force is transmitted from the mode selection lever to the lower-link by means of a push-pull cable. The cable needs to be anchored at the transfer-case end as well. For this purpose a bracket is provided. This bracket (henceforth referred to as lower bracket) is rigidly mounted on to the power train.
From safety point of view direct shifting from high modes (2H, 4H) to low mode (4L) or Neutral mode (N) is not desirable when the vehicle is in motion. To prevent this, a sleeve (henceforth referred to as blocker sleeve) is provided on the lever. This blocker sleeve has a projection which gets guided in a slot provided in a block (henceforth referred to as guide-plate) mounted on the upper bracket. The shape of the slot is such that it prevents direct shifting from high modes (2H,4H) to low mode (4L) or Neutral mode (N).
Any push pull cable will have some dead-play (amount by which it can move at near zero loads). This introduces free play at the knob of mode selection lever. The feeling of free play is not appreciated by the customer and is one of the reasons for customer dissatisfaction. To address this a detent is added which does not allow the slackness of the cable to be felt by the driver. In addition to this the detent ensures that the lever stops at each mode giving precision in shifting,
According to present invention a mechanism for transfer mode selection comprising; a lever for transfer mode selection, said lever is connected to a transfer case shaft through a connecting means, a sleeve with a lateral protrusion is slidably attached to said lever, a guide plate with a stepped slot, said protrusion is extended to said stepped slot and

configured to slide therein such that the protrusion restrict the movement of the lever by butting against the stepped portion in normal position of the sleeve.
Brief description of the Drawings:
FIG (1) is a perspective view showing the Mechanical Shift transfer-case linkage (the topic of current invention) as it is fitted with respect to the BIW and power-train.
FIG (2) is a view from front of the vehicle showing the bracket used for anchoring the cable at the transfer-case end.
FIG (3) shows the mounting of the transfer-case with respect to the gear-box.
FIG (4) is a perspective view of the upper shifter unit.
FIG (5) shows an exploded view of the components which make up the upper shifter unit.
FIG (6) is a view introduced to give more clarity to the construction of upper shifter unit.
FIG (7) is a view showing the link which is mounted on to the transfer-case shaft. It shows the relative position of this link with respect to the bracket used for anchoring the cable at the transfer-case end.
FIG (8) is a section view showing the mounting of Lower bracket (used for anchoring the cable at the transfer-case end) on to the power-train.
FIG (9) is a section view showing the mounting of Lower link on to the transfer-case shaft.
FIG (10) is a view showing how the orientation of lower link is accomplished with respect to the other power-train components.
FIG (11) shows the in -line motion of mode selection gear
FIG (12) shows the motion of mode selection gear in different plane
Detailed description of the Preferred Embodiment:

While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a preferred embodiment of the invention. This is with the understanding that the present disclosure is to be considered as setting forth an exemplification of the invention which is not intended to limit the invention to the specific embodiment illustrated.
Referring now to the drawings, wherein like reference numerals indicate like parts throughout several views, the present invention is arranged in combination with and after being installed, forms an integral part of a part-time 4x4 vehicle. FIG (1) shows the mounting of the linkage on one such vehicle. The linkage consists of an upper shifter unit 2, push-pull control cable 4, assembly lower bracket 9 (shown in FIG (7)) and assembly lower link 11 (shown in FIG (7)). As shown in FIG (1) the tunnel 1 is a part of the BIW of the vehicle. The gear-shift lever 3 of the power-train projects out of the cut-out provided in the tunnel. The upper shifteT unit 1 is mounted on to the tuunti by means of fastening means 45. This upper shifter unit 2 has the lever 46 (shown in FIG (4)) which the driver uses for transfer-case mode selection. Motion and force are transferred from the lever 46 to the transfer-case shaft 12 (shown in FIG (9)) by means of a push-pull control cable 4. One end of the cable (4) is anchored on to the upper bracket 18 (shown in FIG (4)) and the other end of the cable is anchored on to the assembly lower-bracket 9 (shown in FIG (7)). At one end the cable 4 is connected to a ball pin provided on assembly lower-link 11 (which is fastened to the transfer-case shaft 12 (shown in FIG (9))) and at the other end it is connected to a ball pin 35 (shown in FIG (5)) provided on the lever 46.
FIG (2) shows a view from the front of the vehicle-
FIG (3) shows the positioning of the various components of the power-train with respect to each other. The gear-box 5 and the transfer-case 7 are separated by an adaptor housing 6 to place them at appropriate positions with respect to other components of the vehicle. The plane 8 shows the location of the section whose view is shown in FIG (8).
FIG (4) shows a perspective view of the upper shifter unit 2 and the FIG (5) shows an exploded view of the upper shifter unit 2. The upper shifter unit 2 basically

consists of an upper bracket 18, a lever 46 with a sleeve 31 connected to the upper bracket. A knob 34 for holding and shifting attached to the lever 46 with an anti-rotation nut 33. A guide plate 16 is connected to the upper bracket with a stepped slot 16'. The sleeve has a lateral protrusion extended to the stepped slot 16'. In the embodiment shown in figure the sleeve 31 has a pin 24 projecting out of its surface on which a roller 25 is assembled (it is free to roll on the pin). The washer and nut 26 are used to prevent the roller 25 from falling off. The roller 25 rolls about its axis in the annular stepped slot 16' provided in the guide-plate 16. The stepped portion in the slot 16' obstructs the free movement of the roller and hence the roller 25 needs to raise by the help of sleeve 31 to move across the slot 16'.
The upper bracket 18 consists of a frame 38, a pivot pin 36 attached to the frame with a spacer 37, support pieces RH 39 and LH 40 for supporting guide plate 16 and a pin 43 for securing a flat form spring 22. The frame 38 serves for mounting the upper shifter unit 2 on to the tunnel 1. The spacer 37 and pivot pin 36 are welded on to the frame 38. The pivot pin 36 serves as a pivot for the lever 46 to rotate about. Support piece RH 39 and support piece LH 40 are also welded on to the frame 38. The Support piece RH 39 and support piece LH 40 are required to hold the guide plate 16 at the required position. The pin 43 is also welded on to the frame 38. The pin 43 serves as a pivot for the flat form spring 22 as it deflects due to the rotation of the lever 46 about the pivot pin 36.
The lever 46 used by the driver for changing the transfer-case modes consists of the lever upper part 41, stopper 42, a detent 30 and a ball-pin 35 welded together. The bushes 23 and 29 as assembled in to the bore of the detent 30 of the lever 46. This assembly ( of lever 46 and the bushes 23 and 29) is then mounted on to the pivot pin 36. The lever 46 is free to rotate about the pivot pin 36. The spacer 28 and the flange nut 27 are used to ensure that the assembly lever does not come out.
As mentioned earlier direct shifting from high modes to Neutral or low mode is to be avoided. This is accomplished by using a sleeve 31 and guide-plate 16 with stepped slot 16'. The guide-plate 16 is fastened on to the upper bracket 18 by means of fastenings 15 and 17. The guide plate rests on the support piece RH 39 and the support

piece LH 40. The centre of annular slot 16' of guide plate 16 coincides with the centre line of pivot pin 36. Further the sleeve 31 has a square recess so that it can slide on the square portion of the lever upper part 41. The helical spring 32 and the nut 33 ensure that the sleeve is constantly touching and exerting pressure on a stopper 42. Here the nut 33 serves dual purpose, one is to exert pressure on the helical spring 32 and the other is to ensure proper orientation and prevent, rotation of the knob 34. When the driver wishes to change the transfer-case operating mode he applies force at the knob 34. This causes the lever 46 to rotate about the pivot pin 36. As the lever 46 rotates about the pivot pin 36 the roller 25 rolls about its axis in the annular stepped slot 16' provided in the guide-plate 16. The shape of the annular slot is such that if the driver tries to shift from 4H mode to Neutral or 4L mode he will experience a blockage due to the roller 25 encountering the stepped portion in its path. As the roller 25 bangs against the stepped portion the sleeve will have a tendency to rotate about its axis. This rotation is prevented by the square nature of the slot in the sleeve 31 and the corresponding square profile in the lever upper part 41. To avoid rotation, the slot in the sleeve for accessing the lever can be rectangular or any other shapes which restrict the axial rotation of the sleeve about the lever located in the slot. This blockage of motion of the lever 46 helps us to prevent accidents which can occur due to inadvertent gear shifting by the driver. To shift in to neutral or 4L mode from 4H mode the driver has to consciously lift the sleeve 31 which helps the roller to clear the step portion and then shift. The sleeve is provided with a collar to lift it comfortably. The collar can be easily held with the finger during shifting. This restricted movement is only in the direction from 4H mode to the neutral or 4L mode. The lever can be easily shift from neutral or 4L mode to the 4H mode. The shape of the sleeve in the upper portion of the sleeve is such that lifting of the sleeve 31 is comfortable.
Force and motion is transferred from the driver to the lower link 11 via the push-pull control cable 4. This causes rotation of the transfer-case shaft 12 leading to appropriate transfer-case mode selection. The push-pull control cable 4 inherently has some free play due to the nature of its construction. This causes free play at the transfer-case lever and is a potential irritant to the driver. To address this a flat-form spring 22 is

introduced. It is fastened on to the support piece LH 40 by a bolt 21 and a flange nut 20 along with an angle plate 19 (which acts as a support for the flat form spring 22). This flat form spring 22 exerts a constant force on the detent 30. Hence although the cable has a free-play none of it is felt by the driver as the lever 46 is rigidly held in position by the flat form spring 22. The flat form spring 22 and the detent 30 combination also ensures that the lever 46 stops in each mode (i.e. does not skip any mode or it does mot directly go from 4H mode to 4L mode without the driver knowing it).
There is a weld nut 45 provided on the support piece RH 40 as shown in FIG (6). This allows the upper bracket 18 to be used as a mounting location for the floor console of the vehicle.
FIG (7) shows the mounting of the assembly lower link 11 on to the transfer-case shaft 12 (shown in FIG (9)). The mounting arrangement is shown in more detail in FIG (9), which is a section view, referred to by the plane 44 in FIG (7). FIG (10) is a view which is shown by the arrow 14 in FIG (9). This shows by providing a male and female slot the assembly lower link 11 is oriented with respect to the transfer-case 7. The assembly lower link 11 is fastened to the transfer-case shaft 12 by means of the flange nut 13.
FIG (8) shows the lower bracket 9 is mounted on to the adaptor housing 6 by means of two flange nuts lO.This completes the description of the preferred embodiment.
The above described invention has the following advantages vis-a-vis other competing designs:
1. It occupies least packaging space and hence compact.
2. It addresses safety concerns with inline shifting arrangements.
3. It uses cable shifting and hence can be used on a variety of vehicle platforms.
4. It is a cable shifting arrangement in which driver does not experience any free play (which is a customer irritant) at the lever.
5. It is cost effective and makes use of minimum number of parts required.

6. The sleeve and knob used for lift and shift feature has ergonomic design to give comfort to the driver.
7. As the linkage is floor mounted it does not experience vibration problems related to power-train mounted linkages.
8. There is precision in mode selection due to provision of detent.
9. Due to its unique construction it offers flexibility in positioning of the knob with respect to the bracket mounting, cable orientation and routing. This feature again helps it to be used on a variety of vehicle platforms and at the same time causing no inconvenience to the driver.
10. Due to inline construction it is possible to position the linkage at same position for LHD and RHD vehicles without compromising on hand reach of the driver.
Different materials can be used for making the components which make up the invention. The construction of the components can also be different but follow the same general theme presented in the preferred embodiment. This should be understood by all concerned.

We Claim
1. A mechanism for transfer case mode selection comprising; a lever for transfer
case mode selection, said lever is connected to a transfer case shaft through a
connecting means, a sleeve with a lateral protrusion is slidably attached to said
lever, a guide plate with a stepped slot, said protrusion is extended to said
■ stepped slot and configured to slide therein such that the protrusion restrict the movement of the lever by butting against the stepped portion in normal position of the sleeve.
2. The mechanism for transfer mode selection as claimed in claim 1 wherein said protrusion is a pin extended from said sleeve and having a roller attached to it for smooth sliding in the slit.
3. The mechanism for transfer mode selection as claimed in claim 1 wherein said lever is connected to a hinged detent held by a spring in its position for stopping in each mode during shifting.
4. The mechanism for transfer mode selection as claimed in any one of the preceding claims wherein the center line of said stepped annular slot coincides with the centre line of said hinge.
5. The mechanism for transfer mode selection as claimed in claim 1 wherein said sleeve is having a recess for accessing the lever and said recess having a cross sectional shape for restricting the rotation of the sleeve about the lever.
6. The mechanism for transfer mode selection as claimed in claim J wherein said sleeve is located against a stopper on said lever at one end and a compression spring mounted on said lever at other end thereby pushing the sleeve against the stopper.
7. The mechanism for transfer mode selection as claimed in any one of the preceding claims wherein said pin is rolling in the slot freely in a first direction to shift the lever and butt against the stepped portion to restrict the shift of said lever in a second direction opposite to said first direction.

8. The mechanism for transfer mode selection as claimed in claim 7 wherein said sleeve is lifted to raise the pin above the stepped portion to continue the shift in said second direction.
9. The mechanism for transfer mode selection as claimed in any one of the claims wherein said sleeve having a collar to hold the sleeve during lifting.
10. The mechanism for transfer mode selection as claimed in claim 1 wherein said lever is connected to a transfer case shaft through a push pull cable.
11. The mechanism for transfer mode selection as claimed in any one of the claims wherein the detent hinge, the spring and the guide plate are attached to a bracket mounted on the BIW of the vehicle.