FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules  2005

COMPLETE SPECIFICATION
(SEE MEMBER 10 AND RULE 13)

TITLE OF THE INVENTION

“TRANSMISSION SYSTEM FOR WORK VEHICLES”

APPLICANT:

Name : Mahindra & Mahindra Ltd.

Nationality : Indian

Address : Mahindra Research Valley  Mahindra World
City Plot No. 41/1  Anjur P.O. Chengalpattu
Kancheepuram Dist  Tamilnadu.- 603204

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed:-

FIELD OF THE INVENTION

[001] The present invention relates to a transmission system for work vehicles such as tractors and alike.

BACKGROUND OF THE INVENTION

[002] A typical transmission system for work vehicle such as tractor has plurality of gear pairs in speed gear arrangement section for selectively choosing forward movement of the vehicle and a gear pair associated with an intermediate gear for reverse movement of the vehicle. And  two or more gear pairs are provided in the range gear arrangement section for selectively choosing the forward and reverse movement of the vehicle according to the requirement and applications. In this case  the number of forward speed of the vehicle becomes multiplication of number of gear pairs in the speed gear arrangement section and number of gear pairs in the range gear arrangement section and the number of reverse speed of the vehicle becomes multiplication of number of reverse gear pairs in the speed gear arrangement section and number of gear pairs in the range gear arrangement section.

[003] Further development of the aforesaid transmission system has a feature which is commonly known as forward-reverse change over assembly. This type of transmission system will have plurality of gear pairs in the speed gear arrangement section only for forward movement unlike the earlier transmission system  and has a range gear arrangement section. Hence  the vehicle adapted with forward-reverse change over assembly feature has number of speeds equal to number of gear pairs in the speed gear arrangement section and number of gear pairs in the rage gear arrangement section in both forward and reverse movement of the vehicle.

[004] Usually  the forward-reverse change over assembly is disposed in the clutch housing and operated with the help of a lever through manual interpretation. The lever for this operation is in addition to the levers provided for speed gear shifting and range gear shifting.

[005] The typical transmission system of above kind is also provided with a power take-off transmission system. Where a single clutch plate assembly is used with the transmission system  the power take-off transmission system is coupled with the clutch drive shaft with the help of a coupling device which is disposed at the rearward of the transmission system and operated manually with another lever.

[006] In all the above types of transmission system  disposition of aforesaid features such as forward-reverse change over assembly and power take-off coupling device within the given space of the housing and operating of these features through levers is a cumbersome task. Routing of all these levers in addition to other levers such as gear shifting levers at the proximity of the driver seat is again a difficult task  and operation of all these features of the transmission system through manual interpretation shall cause fatigue and tiredness to operator.

[007] To obviate aforesaid difficulties and disadvantages  the transmission system of new generation is incorporated with the forward-reverse change over assembly and power take-off coupling device which are designed to operate hydraulically and the desired pressure is controlled by control valves. Thereby  the operator does not become fatigue due to these features as these are operated hydraulically with less effort. These features are made with plurality of wet clutch plates and associated with a piston arrangement. Another aspect of this transmission system is disposition of said features in the given space available in the housing. This transmission system is generally adapted with vehicle which is used in the construction field as the construction work highly demands frequent forward and reverse movement of the vehicle.

[008] According to the present invention  a forward-reverse clutch pack is incorporated with the clutch drive shaft for functioning forward-reverse movement of the vehicle  which in fact replace conventional clutch plate assembly with a damper plate. Here the damper does the function as same as the clutch assembly and hence  the clutch pedal used otherwise is eliminated while shifting the speed gears. Rather  an inching valve connected to the clutch pedal is pressed to stop the flow of pressurized oil to the forward-reverse clutch pack  thereby not allowing the power flow from engine to speed change section and results in jerk free gear transition. This forward-reverse clutch pack ensures smooth engagement without declutching. All these factors reduce operator fatigue and hence improve productivity.

[009] According to another aspect of the present invention  power take-off clutch pack is also incorporated in the clutch housing just to engage/disengage power take-off transmission system and is actuated similarly as that of forward-reverse clutch pack through another control valve. As such  the damper plate  the forward-reverse clutch pack and power take-off clutch pack are in line with input drive shaft or main drive shaft and housed in the clutch housing.

SUMMARY OF THE INVENTION

[010] According to the present invention  the main objective is to provide a transmission system in which all the three clutches are arranged longitudinally in line with input drive shaft to have reduced vertical dimension of the clutch housing. This also facilitate easy accessibility for service and further repairing after heavy use of wet clutches are become easier without disassembly of the transmission system.

[011] Another object is to eliminate the need of multiple shaft design complexity. Need of more shaft design requires additional bearing system along with another axis parallel to that of the main drive shaft which increases cost. Convenient location of the hydraulic control valves for the forward-reverse clutch pack and power take-off clutch pack ensure easy accessibility for service.

[012] Another object is to the forward-reverse clutch pack and power take-off clutch pack in line with main drive shaft thereby to eliminate any drag which would otherwise be present in any other arrangement of the forward-reverse clutch pack and power take-off clutch pack. Also reduces the number of rotational parts in the system  which will further result in reduction of inertia unlike the effect caused due to the placing of power take-off clutch pack at the rear end of the transmission system.

[013] According to the present invention  a transmission system used with work vehicles such as tractors and alike includes a clutch section at forward end of a housing that encloses the transmission system  subsequent to the clutch section is a speed change section for incorporating a speed gear arrangement and a range gear arrangement for selectively choosing a speed among plurality of speeds available therein  a differential gear section for transferring power from an engine to wheels of the work vehicle and a power take-off transmission section to receive power from the engine to a power take-off output shaft exposed outside of the housing.

[014] In accordance with one aspect of the present invention  the clutch section of the transmission system comprises a damper plate that is secured with a flywheel of the engine and has a through hole along the central axis thereof adapted to operably receive a forward end of an input drive shaft. Subsequent to the damper plate  a forward-reverse clutch pack is disposed longitudinally inside a clutch housing and rotatably supported onto the input drive shaft to change direction of rotation received through the input drive shaft between clockwise and anticlockwise at a transmission drive shaft that is rotatably supported with the clutch housing to transfer engine power to the speed change section; and further  a power take-off clutch pack is disposed inside the clutch housing and rotatably supported at a rear end of the input drive shaft to transfer power received through the input drive shaft to the power take-off transmission section.

[015] In another aspect of the present invention  input drive shaft is rotatably supported inside the clutch housing by its forward end rotatably inserted through a first bearing device disposed at a first wall and rear end rotatably inserted through a second bearing device disposed at a second wall  said first wall is secured with the clutch housing via bolts. The forward-reverse clutch pack is disposed between the first wall and the second wall. The second wall includes a first oil entry path to fluidly communicate with a first oil flow path of the input drive shaft  a second oil entry path to fluidly communicate with a second oil flow path of the input drive shaft to actuate the forward-reverse clutch pack by operating a control lever associated with a control valve through a pressurized oil  and further includes a lubrication oil path adapted to lubricate the forward-reverse clutch pack.

[016] In yet another aspect of the present invention  the power take-off clutch pack is disposed inside the clutch housing and rotatably supported at rear end of the input drive shaft with the help of a mounting plate  wherein said mounting plate is rigidly mounted onto a wall of the clutch housing via bolts and includes a first oil entry path fluidly communicated with a first oil flow path provided in a power take-off clutch drive shaft to actuate the power take-off clutch pack by operating the control lever associated with the control valve through the pressurized oil  and further a lubrication oil path to provide lubrication to the power take-off clutch pack. The power take-off clutch pack includes an input coupling plate operably coupled with the rear end of the input drive shaft and an output coupling plate splined with a first end of the power take-off clutch drive shaft  wherein second end of the power take-off clutch drive shaft is operably coupled with a power take-off coupling shaft via a coupling device.

[017] In yet another aspect of the present invention  the rear end of the input drive shaft is provided with a bore adapted to rotatably receive the first end of the power take-off clutch drive shaft via a bearing device to align the power take-off clutch drive shaft coaxial with the input drive shaft.

[018] In another embodiment of the invention  the forward-reverse clutch pack is integrated with the input drive shaft  wherein the input drive shaft has an outer annular-radial projection adapted to secure with the inner annular-radial projection of the housing of the forward-reverse clutch pack.

[019] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However  it should be understood that the detailed description and specific examples  while indicating preferred embodiments of the invention  are given by way of illustration only  since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[020] The objectives and advantages of the present invention over and above what is explained earlier will become more fully understood from the detailed description given herein below with reference to the accompanying drawings; and the drawings which are shown herein are just for the illustration purpose of principle objective of the present invention  and not to limit the scope of the present invention:

[021] FIG. 1 is a schematic layout of a transmission system used in work vehicles such as tractors incorporated with our present invention.

[022] FIG. 2 is a longitudinal sectional view of the transmission system of FIG.1 in accordance with the present invention and explains the detailed construction and arrangement thereof.

[023] FIG. 3 is an enlarged longitudinal sectional view of an arrangement of power take-off clutch pack disposed in the transmission system of FIG. 2

[024] FIG. 4 is a longitudinal sectional view of another embodiment of the transmission system of FIG.1 in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[025] As the present invention is disposed of embodiments in many different forms  the detailed description of the preferred embodiments and the corresponding drawings shown herein below are to be understood that the present disclosure is an example of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the description below  like reference numerals are used to describe the same  similar or corresponding parts in the several views of FIG 1-3
[026] Referring to FIG. 1  a schematic representation of a transmission system adapted in off road vehicles such as tractors and alike is designated with a reference numeral (100). The transmission system (100) is enclosed in a housing (101) in fore and aft direction  wherein the housing (101) acts as a body frame of the vehicles. Said transmission system (100) is broadly defined as a clutch section (A) at forward end of the housing (101)  subsequent to the clutch section (A) is a speed change section (B) and subsequent to the speed change section (B) is a differential gear section (C) and a power take-off transmission section (D) is disposed at rear end of the housing (101). The clutch section (A) encloses a flywheel (102) that is mounted onto an internal combustion engine (not shown)  and secured with the flywheel (102) is a damper plate (103) which has a through hole (104) along the central axis thereof and provided with splines adapted to receive forward end (105) of an input drive shaft (106). Further  the clutch section (A) encloses a forward-reverse clutch pack (107) that is rotatably supported onto the input drive shaft (106) to change direction of rotation received through the input drive shaft (106) between clockwise and anticlockwise and to transfer the power to the speed change section (B)  and a power take-off clutch pack (109) rotatably supported at a rear end (108) of the input drive shaft (106) to transfer power received through the input drive shaft (106) to power take-off transmission section (D).

[027] The speed change section (B) comprises a speed gear arrangement (110) and a range gear arrangement (111)  wherein the speed gear arrangement (110) includes a first main shaft (112) and a first counter shaft (113). A plurality of drive gears (114) disposed at the first main shaft (112) are being constantly engaged with a corresponding plurality of driven gears (115) disposed at the first counter shaft (113) to transfer required rotational power at wheels. The range gear arrangement (111) is disposed at rearward of the speed gear arrangement (110) to complement the speeds available at the speed gear arrangement (110). The range gear arrangement (111) includes a second main shaft (116) and a second counter shaft (117)  wherein a plurality of drive gears (118) disposed at the second main shaft (116) are being constantly engaged with a corresponding plurality of driven gears (119) disposed at the second counter shaft (117) to transfer required rotational power at wheels. As such the speed gear arrangement (110) and the range gear arrangement (111) are adapted for selectively choosing a speed for the work vehicle among plurality of speeds available therein. The first main shaft (112) of the speed change section (B) receives the engine power through a transmission drive shaft (120) which is rotatably supported at the clutch section (A).

[028] The differential gear section comprises a pinion gear (121) and a ring gear (122) engaged with each other in association with a differential unit (not shown) to transfer the engine power to the wheels. The power take-off transmission section (D) comprises a power take-off input shaft (123) associated with a plurality of drive gears (124) adapted to engage with a corresponding plurality of driven gears (125) associated with a power take-off output shaft (126) which is exposed outside of the housing (101) to transfer power to earthmoving implements and devices which require rotational power.

[029] Referring to FIG.2  the clutch section (A) is isolated from the speed change section (B) by a wall (127) transversely and enclosed by a clutch housing (128). The input drive shaft (106) is rotatably supported inside the clutch housing (128) by its forward end (105) rotatably inserted through a first bearing device (129) disposed at a first wall (130) and rear end (108) rotatably inserted through a second bearing device (131) disposed at a second wall (132). The first wall (130) is secured with the clutch housing (128) via bolts. The forward-reverse clutch pack (107) is disposed between the first wall (130) and the second wall (132)  and includes a housing (133) that is splined with the input drive shaft (106) to receive the engine power.

[030] Referring to FIG.4  according to another embodiment of the invention  the forward-reverse clutch pack (107) is integrated with the input drive shaft (106). Wherein  the input drive shaft (106) has an outer annular-radial projection (106a) adapted to secure with the inner annular-radial projection (133) of the housing (133) of the forward-reverse clutch pack (107).

[031] A first drive gear (134) and a second drive gear (135) are operably configured with the housing (133) of forward-reverse clutch pack via plurality of friction plate and clutch plate and constantly engaged with a first driven gear (136) and a second driven gear (137)  respectively  wherein the first driven gear (136) and the second driven gear (137) are splined with the transmission drive shaft (120). An intermediate gear (not shown) is disposed between the first drive gear (134) and the first driven gear (136) and constantly engaged with each other to have a direction of rotation opposite of the rotation of the second driven gear (137).

[032] The second wall (132) is substantially thick enough to incorporate a first oil entry path (138) to fluidly communicate with a first oil flow path (139) and a second oil entry path (140) to fluidly communicate with a second oil flow path (141) of the input drive shaft (106). Also a lubrication oil path (142) is provided through the thick wall (132) to provide sufficient lubrication to the forward-reverse clutch pack (107). When a control lever (not shown) associated with a control valve (143) is actuated for forward movement of the vehicle  pressurized oil flows through the first oil entry path (138) and then to the first oil flow path (139) to push a first piston (144) associated with the forward-reverse clutch pack (107) and thereby to transfer the power from the housing (133) to the second drive gear (135) via the plurality of frication plate and clutch plate  which in turn transfer the power to the second driven gear (137). When the control lever is actuated for reverse movement of the vehicle  pressurized oil flows through the second oil entry path (140) and then to the second oil flow path (141) to push a second piston (145) associated with the forward-reverse clutch pack (107) and thereby to transfer the power from the housing (133) to the first drive gear (134) via the plurality of frication plate and clutch plate  which in turn transfer the power to the first driven gear (136).

[033] Referring to FIG. 3  the power take-off clutch pack (109) is rotatably disposed rearward of the clutch housing (128) with the help of a mounting plate (146)  wherein said mounting plate (146) is rigidly mounted onto a wall (147) which is transverse to the axis of the clutch housing (128) via fastening means such as bolts. The power take-off clutch pack (109) includes an input coupling plate (148) engaged with rear end (108) of the input drive shaft (106) via splines provided at outer circumference therein and an output coupling plate (149) splined with a first end (150) of a power take-off clutch drive shaft (151)  wherein second end of the power take-off clutch drive shaft (151) is coupled with a power take-off coupling shaft (152) via a coupling device (153). The rear end (108) of the input drive shaft (106) has a bore (154) adapted to rotatably receive the first end (150) of the power take-off clutch drive shaft (151) via a bearing device (155) to align the power take-off clutch drive shaft (151) coaxial with the input drive shaft (106). The power take-off clutch drive shaft (151) is rotatably supported in the mounting plate (146) through bearing means (156). The input coupling plate (148) and the output coupling plate (149) is configured with each other via plurality of clutch plate and friction plates (157) and operably associated with a piston (158) in such a way to transfer power from the input coupling plate (148) to the output coupling plate (149). The mounting plate (146) is incorporated with a first oil entry path (159) and further fluidly communicated with a first oil flow path (160) provided in the power take-off clutch drive shaft (151). When a control lever (not shown) associated with the control valve (143) is actuated for engaging the power take-off clutch drive shaft (151) with the input drive shaft (106)  pressurized oil flows through the first oil entry path (159) and then to the first oil flow path (160) to push the piston (158) associated with the power take-off clutch pack (109) and thereby to transfer the power from the input coupling plate (148) to the output coupling plate (149) via plurality of frication plate and clutch plate  which in turn transfer the power to the power take-off output shaft (126) via power take-off coupling shaft (152). Also a lubrication oil path (161) is provided through the mounting plate (146) to provide sufficient lubrication to the power take-off clutch pack (109).

CLAIMS
We claim 
1) A transmission system (100) for work vehicles includes a clutch section (A) at forward end of a housing (101) that encloses the transmission system (100)  subsequent to the clutch section (A) is a speed change section (B) for incorporating a speed gear arrangement (110) and a range gear arrangement (111) for selectively choosing a speed among plurality of speeds available therein  a differential gear section (C) for transferring power from engine to wheels and a power take-off transmission section (D) to receive power from engine to a power take-off output shaft (126) exposed outside of the housing (101)  said clutch section (A) comprises:

a damper plate (103) that is secured with a flywheel (102) of an internal combustion engine (not shown) and has a through hole (104) along the central axis thereof adapted to operably receive a forward end (105) of an input drive shaft (106);

a forward-reverse clutch pack (107) that is disposed inside a clutch housing (128) and rotatably supported onto the input drive shaft (106) to change direction of rotation received through the input drive shaft (106) between clockwise and anticlockwise at a transmission drive shaft (120) that is rotatably supported with the clutch housing (128) to transfer engine power to the speed change section (B); and

a power take-off clutch pack (109) which is disposed inside the clutch housing (128) and rotatably supported at a rear end (108) of the input drive shaft (106) to transfer power received through the input drive shaft (106) to the power take-off transmission section (D).

2) The transmission system (100) claimed in claim 1  wherein the input drive shaft (106) is rotatably supported inside the clutch housing (128) by its forward end (105) rotatably inserted through a first bearing device (129) disposed at a first wall (130) and rear end (108) rotatably inserted through a second bearing device (131) disposed at a second wall (132)  said first wall (130) is secured with the clutch housing (128) via bolts.

3) The transmission system (100) claimed in claim 1  wherein the forward-reverse clutch pack (107) is disposed between the first wall (130) and the second wall (132).

4) The transmission system (100) claimed in claim 3  wherein the second wall (132) includes a first oil entry path (138) to fluidly communicate with a first oil flow path (139) of the input drive shaft (106)  a second oil entry path (140) to fluidly communicate with a second oil flow path (141) of the input drive shaft (106) to actuate the forward-reverse clutch pack (107) by operating a control lever associated with a control valve (143) through a pressurized oil  and a lubrication oil path (142) adapted to lubricate the forward-reverse clutch pack (107).

5) The transmission system (100) claimed in claim 1  wherein the power take-off clutch pack (109) is disposed inside the clutch housing (128) and rotatably supported at rear end (108) of the input drive shaft (106) with the help of a mounting plate (146)  said mounting plate (146) is rigidly mounted onto a wall (147) of the clutch housing (128) via bolts.

6) The transmission system (100) claimed in claim 1  wherein the power take-off clutch pack (109) includes an input coupling plate (148) operably coupled the rear end (108) of the input drive shaft (106) and an output coupling plate (149) splined with a first end (150) of a power take-off clutch drive shaft (151)  wherein second end of the power take-off clutch drive shaft (151) is operably coupled with a power take-off coupling shaft (152) via a coupling device (153).

7) The transmission system (100) claimed in claim 6  wherein the rear end (108) of the input drive shaft (106) has a bore (154) adapted to rotatably receive the first end (150) of the power take-off clutch drive shaft (151) via a bearing device (155) to align the power take-off clutch drive shaft (151) coaxial with the input drive shaft (106).

8) The transmission system (100) claimed in claim 5  wherein the mounting plate (146) includes a first oil entry path (159) fluidly communicated with a first oil flow path (160) provided in the power take-off clutch drive shaft (151) to actuate the power take-off clutch pack (109) by operating the control lever associated with the control valve (143) through the pressurized oil  and a lubrication oil path (161) to provide lubrication to the power take-off clutch pack (109).

Date: 28 September  2012 Signature

Dr. Kalyan Chakravarthy

ABSTRACT

A transmission system for work vehicles includes a clutch section at forward
end of housing. The clutch section comprises a damper plate that is secured
with a flywheel of an engine and has a through hole along the central axis
thereof to engage a forward end of an input drive shaft. A forward-reverse
clutch pack is disposed inside a clutch housing and supported onto the input
drive shaft to change direction of rotation received through the input drive
shaft between clockwise and anticlockwise at a transmission drive shaft that
is rotatably supported with the clutch housing to transfer engine power to a
speed change section. A power take-off clutch pack is disposed inside the
clutch housing and rotatably supported at a rear end of the input drive
shaft to transfer power received through the input drive shaft to a power
take-off transmission section. Reference fig: 2