F0RM2
THE PATENTS ACT 1970
(39 of 1970)
AND
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rulel3)
1. TITLE OF THE INVENTION:
"POWER TAKE-OFF SHIFTING SYSTEM FOR WORK VEHICLES"
2. APPLICANT:
(a) NAME: MAHINDRA & MAHINDRA LTD.
(b)NATIONALITY: Indian Company incorporated under the Companies Act, 1956
(c) ADDRESS: Gateway Building, Apollo Bunder, Mumbai - 400001, Maharashtra, India.
3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which it is to be formed.

FIELD OF THE INVENTION:
The present invention relates to a Power Take-Off (PTO) system used with agricultural and construction vehicles such as tractors and alike, and more particularly concerned with a power take off shifting system for completely availing power available at a combustion engine to the power take-off system especially when the work vehicle is motionless.
BACKGROUND OF THE INVENTION:
It is very common in the field of agricultural and industrial applications to endow with an additional power source what is referred as a Power Take-Off (PTO) transmission system to work with or operate machineries, farm equipments or devices which require rotational input speed to perform its operation. In general, unlike on-road vehicle applications, off-road vehicles are used for various operations with diverse implements or equipments in field. The power take-off system associated with work vehicles such as tractors, trucks and construction vehicles, is generally operated at two situations either during travel of the work vehicles or when the work vehicle is motionless. For example, implements such as rotavators and mowers are operated with work vehicles when they are running; in this case, the power generated from the combustion engine is shared by wheel of the vehicle and the power take-off transmission system. But, equipments such as hydraulic pump, electric generator and cement mixer are operated by receiving power from the power take-off system when the wok vehicle stationary. During this operation, the power generated by the engine is transferred only to power take-off shaft.
There are work vehicles which provide power take-off transmission system to work with aforesaid diverse implements during the running time of the vehicles as well as at stationary position. In work vehicles, different arrangements have been proposed to derive power from the engine to the power take-off transmission system. One method is deriving power available at flywheel of the engine via an additional clutch apart from the conventional clutch provided for transferring power to speed reduction transmission system, which is generally referred as dual clutch transmission system. Another method, in single clutch transmission system, is taking power from the speed reduction transmission system by connecting power take off input shaft directly to either counter shaft or main shaft of the speed reduction transmission system as per the requirement. Yet another method includes transfer of engine power directly from the engine using

conventional clutch by inserting the power take-off input shaft through the main shaft of the speed reduction transmission system. All these methods are incorporated along with the clutch housing and transmission housing suitably to be operated by the operator with help of a lever. In all the aforesaid arrangements, power take-off output shaft is coupled with a coupling shaft via a dog clutch for receiving power from the engine and for selectively engaging and disengaging the power at power take-off output shaft from the engine or speed reduction transmission system, as applicable. The dog clutch is operated by the operator with the help of the lever, which is commonly referred as power take-off lever.
In work vehicles where single clutch transmission system is used, a speed reduction input shaft is used to receive power from clutch drive shaft and transfer to the speed reduction transmission system which in turn transfer the power to the wheel of the vehicle. The speed reduction input shaft is a hollow shaft that receives the power take-off coupling shaft there through and being adapted to receive power from the clutch drive shaft. The power take-off coupling shaft coupled with power take-off input shaft via the dog clutch for selectively transferring the engine power to the power take-off input shaft. In this construction, when clutch plate is engaged with flywheel of the engine, the power is getting transferred to the speed reduction input shaft and the power take-off coupling shaft. As such, when the work vehicle is in running condition, by engaging the power take-off coupling shaft and the power take-off input shaft, the power shall be simultaneously transferred to the power take-off output shaft. But, the present invention is concerned about a situation where only the power take-off power is required to be operated to work with some equipments while work vehicle is stationary, in such situation, it is very obvious that the power from the engine is transferring to the speed reduction transmission system along with power take-off output shaft. This will cause unnecessary rotation of gear pairs present in the speed reduction transmission system as it is in neutral condition. As a result of this power flow to the speed reduction transmission system, the actual power to be transferred to the power take-off output shaft is getting reduced due to the following losses in the gear box: gear mesh loss - this loss is due to the power consumed by the gears to overcome the inertia possessed by each gear pair and further rotation continuously, Churning loss - this loss occurs due to the transmission oil present in the transmission housing, wherein the oil is churned by the rotation of the gears

and leading to power loss depending on the viscosity of the oil used, Drag loss - while the gear box input shaft is in rotation, it consume power to overcome the drag exerted on to it by the oil seals & bearings.
All these losses contribute to lesser power available at the Power take off output shaft to perform applications efficiently, which eventually leads to lesser efficiency at the Power take-off output shaft. Hence, to have the power received from the engine at the power take-off output shaft completely, there is a need remains in this field to avoid the power transfer to the speed reduction transmission system when only the power take-off system is operated while the work vehicle is stationary so as to get maximum work efficiency of the power take-off system also to avoid unnecessary power losses and thereby increases reliability of the speed reduction transmission system and transmission oil. The preferred embodiment of the present invention also eliminates the dog clutch conventionally used to selectively engage and disengage the power take-off input shaft with and from the power take-off coupling shaft.
SUMMARY OF THE INVENTION:
According to one aspect of the present invention, a power take-off drive shifting system comprises a power take-off drive coupling and a dog clutch, wherein the power take-off drive coupling has inner diameter provided with splines adapted to engage with splines at forward end of a power take-off coupling shaft and outer diameter is provided with splines in similar with the splines at second end of a clutch drive shaft and the splines at first end of a speed reduction input shaft, and inserted over the forward end of the power take-off coupling shaft for operably disposing in a slot defined between the speed reduction input shaft and the clutch drive shaft. The dog clutch is cylindrical in shape and has an inner diameter defined by a first limb and a second limb having provided with splines adapted to slidably engage with splines of the clutch drive shaft, the splines of the speed reduction input shaft and splines provided at outer diameter of the power take-off drive coupling. Width of the second limb is made sufficiently bigger than the first limb so as to engage the power take-off drive coupling with either the clutch drive shaft or speed reduction input shaft, as and when required- The first limb and the second limb define a

first slot at inner diameter of the dog clutch having width bigger than width of the power take-off drive coupling. A second slot is provided at outer diameter of the dog clutch adjacent to second end adapted to receive an end of a power take-off lever for selectively engaging and disengaging the power from the engine to either power take-off coupling shaft or the speed reduction input shaft or both by the operator.
When the dog clutch is positioned at its maximum extend in forward direction, it engages the clutch drive shaft with the power take-off drive coupling and thereby the power generated by the engine is transferred from the clutch drive shaft to the power take-off output shaft, but the engine power is not transferred to the speed reduction input shaft and hence ensure availability of complete engine power at the power take-off output shaft without any loss of power. When the dog clutch moves a step backward, it engages the clutch drive shaft with the power take-off drive coupling and the speed reduction input shaft, thereby the power is transferred from the clutch drive shaft to the speed reduction input shaft and the power take-off output shaft. When the dog clutch moves a step further backward, it engages the clutch drive shaft with the speed reduction input shaft, and thereby the power is transferred from the clutch drive shaft to the speed reduction input shaft.
According to another aspect of the present invention, a power take-off drive shifting system comprises the power take-off drive coupling, a dog clutch for engaging the speed reduction input shaft and the power take-off drive coupling, and a fixed coupling for engaging the clutch drive shaft and the power take-off drive coupling. The dog clutch is actuated by a power take-off lever. Conventional coupling device is used to engage and disengage the power take-off input shaft with the power take-off coupling shaft as and when required. According to this aspect of the present invention, the power take-off coupling shaft is always in rotation, as such, at any situation of the work vehicle and shifting position of the power take-off drive shifting system, the power shall be transferred to the power take-off output shaft via the coupling device.
When the dog clutch is positioned at maximum extend in forward direction, it engages the power take-off drive coupling and the speed reduction input shaft, thereby the engine power from the clutch drive shaft is transferred to the speed reduction transmission

system. When the dog clutch is shifted a step backward, it disengages the power take-off drive coupling and thereby the power from the engine is not transferred to the speed reduction transmission system while the power take-off coupling shaft is continuously receiving power from the clutch drive shaft according to the principal objective of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS:
Further features and advantages, as well as the structure and operation of various embodiments of the present invention, are described in detail herein below with reference to the accompanying drawings, wherein: FIG.l is a longitudinal section view of transmission body of a work vehicle incorporating
preferred embodiment, a power take off drive shifting system according to the
present invention. FIG.2 is an enlarged longitudinal section view of the power take off drive shifting system
of FIG.l configured to describe power flow only to a power take off transmission
system. FIG.3 is an enlarged longitudinal section view of the power take off drive shifting system
of FIG.l configured to describe power flow to speed reduction transmission
system and the power take off transmission system. FIG.4 is an enlarged longitudinal section view of the power take off drive shifting system
of FIG.l configured to describe power flow only to the speed reduction
transmission system. FIG.5 is a longitudinal section view of the transmission body of the work vehicle
incorporating another embodiment according to the present invention. FIG.6 is an enlarged longitudinal section view of the power take off drive shifting system
of FIG.5 configured to describe power flow only to the speed reduction
transmission system and the power take off transmission system. FIG.7 is an enlarged longitudinal section view of the power take off drive shifting system
of FIG.5 configured to describe power flow only to the power take off
transmission system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
Nevertheless, the present invention is susceptible 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 disclosure shall be deemed as 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 1-7.
Accordingly, the present invention discloses a Power Take-off (PTO) drive shifting system for ensuring availability of complete power from the engine to a PTO output shaft without any loss during stationary condition of a vehicle comprising a PTO drive coupling and a dog clutch, wherein said dog clutch when positioned at the maximum extend in forward direction engages a clutch drive shaft with said PTO drive coupling, whereby the power generated by the engine is transferred from said clutch drive shaft to said PTO output shaft and not to a speed reduction input shaft, and wherein said dog clutch when positioned at a step backward than the maximum engages said clutch drive shaft to said speed reduction input shaft & said PTO drive coupling whereby the power is transferred from said clutch drive shaft to said speed reduction input shaft and said PTO output shaft, and wherein said dog clutch when positioned a step further backwards from the maximum engages said clutch drive shaft with said speed reduction input shaft whereby the power is transferred from said clutch drive shaft to said speed reduction input shaft.
Referring to FIG.l, a work vehicle such as tractor and alike has a transmission body (100) that is generally referred as 'skid' of the tractor and acts as a complete supporting structure for the tractor like what a chassis does for an on-road vehicle. The transmission body has a clutch housing (101) and a transmission housing (102), wherein the clutch housing encloses a flywheel (103), a clutch assembly (104) and the transmission housing encloses a speed reduction transmission system (105) and a power take off (PTO) transmission system (105). The present invention is more concerned with a transmission system of the work vehicle where a single clutch plate is used for transferring power available at engine to the speed reduction transmission system and the power take off

transmission system. According to the present invention, to selectively transfer the power to the speed reduction transmission system (105) and the power take off transmission system (106), a power take off drive shifting system (107) in accordance with preferred embodiment of the present invention is disposed in the clutch housing (101).
The clutch assembly (104) has a clutch plate (108) that is splined with first end (109a) of a clutch drive shaft (109) to transfer power from engine to the speed reduction transmission system (105) and the power take off transmission system (106). The clutch drive shaft (109) is rotatably supported with the clutch housing (101) at a housing wall (110) via a bearing assembly (111). The speed reduction transmission system (105) includes a speed reduction input shaft (112) which is hollow throughout the length thereof and rotatably supported with the transmission housing at housing walls via bearing assemblies. Said speed reduction input shaft (112) is adapted to receive plurality of drive gears (113) to engage with corresponding plurality of gears (114) disposed at a counter shaft (115) of the speed reduction system (105). Forward end (112a) of the speed reduction input shaft (112) is provided with splines (112c).
The power take off transmission system (106) has a power take-off input shaft (116) to receive power from the clutch drive shaft (109) via a power take-off coupling shaft (117) which in turn further transferred to a power take-off output shaft (118) via plurality of gears (119). Forward end (117a) of the power take-off coupling shaft (117) is inserted through the speed reduction input shaft (112) and backward end (117b) is coupled with a fist end (116a) of the power take-off input shaft (116). Second end (116b) of the power take-off input shaft (116) is disposed with the plurality of gear (119) to transfer the power to the power take-off output shaft (118), backward end (118b) of which is exposed outside the transmission housing (102) at back end of the work vehicle to removably connect with implements or equipments which needs rotational input drive to perform its operation. It is to be understood from the aforesaid description with reference to FIG.l that transmission layout described herein is exemplary and to explain the principle of construction of the transmission system with which the power take-off drive shifting system according to the present invention is associated, and not intend to limit the scope of the present invention. There are power take-off transmission systems with power take-

off output shaft disposed at back end, front end and mid of the work vehicle, as applicable.
In conventional power take-off drive system, the first end (116a) of the power take-off input shaft (116) is coupled with the backward end (117b) of the coupling shaft (117) for selectively engaging and disengaging power take-off power from the engine power via a coupling device. Said coupling device is operated by a power take-off lever (not shown) which is disposed at the proximity of operator to comfortably operate the power take-off lever during running condition of the work vehicle. As the present invention is more concerned with operation of the power take-off transmission system during the standstill condition of the work vehicle and also to reduce complexity in number of components and its design and manufacturing, this conventional shifting system is also being integrated with the power take-off drive shifting system according to preferred embodiment of the present invention, and construction and best method of working of which is being described herein below in detail with reference to FIG.2 to FIG.4.
Referring to F1G.2 to FIG.4, second end (109b) of the clutch drive shaft (109) is provided with splines (109c) at outer circumference thereof and a bore adapted to accommodate the forward end (117a) of the power take-off coupling shaft (117). Said forward end (117a) is also provided with splines (117c) at outer circumference thereof adapted to operably associate with the power take-off drive shifting system and extended outward of the forward end (112a) of the speed reduction input shaft (112) till the second end (109b) of the clutch drive shaft (109) coaxially and thereby define a slot between the forward end (112a) of the speed reduction input shaft (112) and the second end (109b) of the clutch drive shaft (109). The power take-off drive shifting system (107) according to the preferred embodiment of the present invention comprises a power take-off drive coupling (120) and a dog clutch (121), wherein the power take-off drive coupling (120) has inner diameter provided with splines adapted fixedly to engage with splines (117c) of the power take-off coupling shaft (117) and outer diameter is provided with splines in similar with the splines (109c) of the clutch drive shaft (109) and the splines (112c) of the speed reduction input shaft (112), and inserted over the forward end (112a) of the power takeoff coupling shaft for operably disposing in the slot defined between the forward end (112a) of the speed reduction input shaft (112) and the second end (109b) of the clutch

drive shaft (109). The dog clutch (121) is cylindrical in shape and has an inner diameter defined by a first limb (121a) at first end (121c) and a second limb (121b) at a second end (121d) as shown in FTGs having provided with splines adapted to slidably engage with splines (109c) of the clutch drive shaft (109), the splines (112c) of the speed reduction input shaft (112) and splines provided at outer diameter of the power take-off drive coupling (120). Width of the second limb (121b) is made sufficiently bigger than the first limb (121a) so as to engage the power take-off drive coupling (120) with either the clutch drive shaft (109) or speed reduction input shaft (112), as and when required. The first limb (121a) and the second limb (121b) define a first slot (121e) at inner diameter of the dog clutch (121) having width bigger than width of the power take-off drive coupling (120). A second slot (121f) is provided at outer diameter of the dog clutch (121) adjacent to the second end (121d) adapted to receive an end of a power take-off lever (not shown) for selectively engaging and disengaging the power from the engine to either power takeoff coupling shaft (117) or the speed reduction input shat (112) or both the power take-off coupling shaft (117) and the speed reduction input shat (112) by the operator.
The best method of working of the preferred embodiment of the present invention is described herein below with reference to FIG.2 to FIG.4, separately.
Referring to FIG.2, according to the preferred embodiment of the present invention, the dog clutch (121) is positioned at its maximum extend in forward direction, and hence the first limb (121a) is engaged with the spline (109c) of the clutch drive shaft (109) and second limb (121b) engages with the splines provided at outer diameter of the power take-off drive coupling (120) and the splines (109c) of the clutch drive shaft (109). In this shifting position of the dog clutch (121), the power generated by the engine is transferred from the clutch drive shaft (109) via the clutch plate (108) to the power take-off coupling shaft (117) and thereby to the power take-off output shaft (118) as the power take-off coupling shaft (117) is engaged with the power take-off drive coupling (120), and the engine power is not transferred to the speed reduction input shaft (112) and hence ensure availability of complete engine power at the power take-off output shaft without any loss of power, which would otherwise cause loss of power due to the losses at the speed reduction transmission system as the gears are rotating unnecessarily.

Referring to FIG.3, the dog clutch (121) moves a step backward and hence the first limb (121a) is engaged with the spline (109c) of the clutch drive shaft (109) and second limb (121b) engages with the splines provided at outer diameter of the power take-off drive coupling (120) and the splines (112c) of the speed reduction input shaft (112). In this shifting position of the dog clutch (121), the power generated by the engine is transferred from the clutch drive shaft (109) via the clutch plate (108) to the speed reduction input shaft (112) and to the power take-off coupling shaft (117) and thereby to the power takeoff output shaft (118). This shifting position is generally maintained when power take off transmission is also to be operated during running condition of the work vehicle.
Referring to FIG.4, the dog clutch (121) moves a step further backward and hence the first limb (121a) is engaged with the spline (109c) of the clutch drive shaft (109) and second limb (121b) engages with the splines (112c) of the speed reduction input shaft (112). In this shifting position of the dog clutch (121), the power generated by the engine is transferred from the clutch drive shaft (109) via the clutch plate (108) to the speed reduction input shaft (112) and the power take-off coupling shaft (117) becomes stationary. This shifting position of the dog clutch functionally eliminate provision of coupling means for engaging and disengaging the power take-off input shaft (118) with the power take-off coupling shaft (117) in conventional system.
Thus the preferred embodiment of the present invention provide the power take-off drive shifting system that involves complete aspects required for a power take-off transmission to work without adding much complexity in parts, design and development thereof. Another embodiment of the present invention is described herein below with reference to FIG.5 to FIG.7 in accordance with principal objective of the invention, wherein a power take-off drive shifting system is described that is simply adapted with the conventional power take-off drive shifting system without much modification.
Referring to FIG. 5, the power take-off drive shifting system (122) comprises said power take-off drive coupling (120), a dog clutch (123) having inner diameter provided with splines adapted to slidably engage with splines (112c) of the speed reduction input shaft (112) and splines provided at the outer diameter of the power take-off drive coupling (120) and a fixed coupling (124) having inner diameter provided with splines adapted to

fixedly engage with the splines (109c) of the clutch drive shaft (109) and the splines provided at the outer diameter of the power take-off drive coupling (120). The dog clutch (123) has a slot (123a) at outer diameter adapted to engage with one end of a power takeoff lever (not shown) for comfortably operating the power take-off drive shifting system
(122) by the operator. The transmission housing (102) has a coupling device (125)
adapted to engage and disengage the first end (116a) of the power take-off input shaft
(116) with the backward end (117b) of the power take-off coupling shaft (117) as and
when required. According to this embodiment of the present invention, the power take-off
coupling shaft (117) is always engaged with the clutch drive shaft (109) via the fixed
coupling (124), as such, at any situation of the work vehicle and shifting position of the
power take-off drive shifting system (122), the engine power shall be always available at
the power take-off coupling shaft (117), and the coupling device (125) is operated by an
lever (not shown) by the operator to engage and disengage the power from the power
take-off coupling shaft (117) to the power take-off output shaft (118).
The method of working of the embodiment of the present invention is described here in below with reference to the FIG.6 and FIG.7, separately.
Referring to FIG.6, the dog clutch is positioned at maximum extend in forward direction, hence to engage with splines provided at the outer diameter of the power take-off drive coupling (120) and the splines (112c) of the speed reduction input shaft (112), thereby to transfer the engine power from the clutch drive shaft (109) via the clutch plate (108) to the speed reduction transmission system (105). Referring to FIG.7, when the dog clutch
(123) is shifted a step backward with the help of the power take-off lever, it disengaged
with the power take-off drive coupling (120) and thereby the power from the engine is not
transferred to the speed reduction transmission system while the power take-off coupling
shaft (117) is continuously receiving power from the clutch drive shaft (109) according to
the principal objective of the present invention.
An advantage of the present invention is that it provides aforesaid power take-off drive shifting system to a transmission system having operated with a single clutch plate assembly where the power to the power take-off output shaft from the engine is directly transferred from the clutch drive shaft by inserting the power take-off coupling shaft

through the speed reduction input shaft. By disposing the power take-off drive shifting system between the clutch drive shaft and the speed reduction input shaft, as and when required, the power to the speed reduction transmission system shall be avoided to effectively transfer the complete engine power to the power take-off output shaft and thereby to maximize the efficiency of the power take-off transmission system during standstill condition of the work vehicle.
Another advantage of the power take-off drive shifting system is that it avoids unnecessary rotation of the gear pairs while the power take-off transmission system is in operation when the work vehicle is positioned stand-still at particular place to work with power take-off driven equipments. This eventually reduces gear mesh losses, churning losses and drag losses of the speed reduction transmission system which in turn increases reliability and durability of the speed reduction transmission system by way of maintaining the transmission oil efficiency and efficiency of other transmission components due to limited use of speed reduction transmission system.
Another additional benefit of the present invention is that the coupling device that used to engage and disengage power from the power take-off coupling shaft to the power take-off input shaft in the conventional power take-off transmission system is eliminated. This further adds to cost advantage in reduced number of parts and design & development thereof.

We claim,
1. A Power Take-off (PTO) drive shifting system(I07) for ensuring availability of
complete power from the engine to a PTO output shaft(118) without any loss
during stationary condition of vehicle comprising a PTO drive coupling(120) and
a dogclutch(121),
wherein said dog clutch(121) when positioned at the maximum extend in forward direction, engages a clutch drive shaft(109) with said PTO drive coupling(120), whereby the power generated by the engine is transferred from said clutch drive shaft(109) to said PTO output shaft(l 18) and not to a speed reduction input shaft(112), and
wherein said dog clutch(121) when positioned at a step backward than the maximum, engages said clutch drive shaft(109) to said speed reduction input shaft(l 12) & said PTO drive coupling(120) whereby the power is transferred from said clutch drive shaft(109) to said speed reduction input shaft(l 12) and said PTO output shaft, and
wherein said dog clutch(121) when positioned a step further backwards from the maximum, engages said clutch drive shaft(109) with said speed reduction input shaft(l 12) whereby the power is transferred from said clutch drive shaft(109) to said speed reduction input shaft(l 12).
2. The PTO drive shifting system(107) as claimed in claim 1, wherein said PTO coupling(120) has inner diameter provided with splines adapted fixedly to engage with splines(l 17c) at forward end(l 17a) of a PTO coupling shaft(l 17) and outer diameter is provided with splines in similar with splines(109c) at second end(109b) of a clutch drive shaft(109) and splines(l 12c) at first end of a speed reduction input shaft( 112) and inserted over forward end(112a) of said PTO coupling shaft(l 17) for operably disposing in a slot defined between said forward end(l 12a) of said speed reduction input shaft(l 12) and said second end(109b) of said clutch drive shaft(109).
3. The PTO drive shifting system(107) as claimed in claim 2, wherein said second end(109b) of said clutch drive shaft(109) is provided with a bore adapted to accommodate the forward end(l 17a) of said PTO coupling shaft(l 17).

4. The PTO drive shifting system(107) as claimed in claim 3, wherein backward end(l 17b) of said PTO coupling shaft(117) is coupled with a first end(l 16a) of a PTO input shaft(l 16).
5. The PTO drive shifting system(107) as claimed in claim 1, wherein said dog clutch(121) has an inner diameter defined by a first limb(121a) at first end(121c) and a second limb(121b) at second end(121d).
6. The PTO drive shifting system(107) as claimed in claims 1 & 2, wherein said dog clutch(121) is provided with splines adapted to slidably engage with said splines(109c) of said clutch drive shaft(109), said splines (112c) of said speed reduction input shaft (112) and splines provided at outer diameter of said PTO drive coupling(120).
7. The PTO drive shifting system(107) as claimed in claim 5, wherein width of said second limb(121b) is more than said first Iimb(121a) to engage said PTO drive coupling(120) with either said clutch drive shaft(109) or said speed reduction input shaft(l 12) as per the requirement.
8. The PTO drive shifting system(107) as claimed in claim 1, 2 & 4, wherein a second slot(121f) is provided at outer diameter of said dog clutch(121) adjacent to said second end (121d) and is adapted to receive an end of a PTO lever for selectively engaging and disengaging the power from the engine to either PTO coupling shaft(117) or said speed reduction input shaft(l 12) or both as per the requirement.
9. A PTO drive shifting system (122) to ensure availability of complete power from the engine to a PTO output shaft(l 18) without any loss during stationary condition of vehicle comprising a PTO drive coupling(120), a dog clutch(123) and a fixed coupling(124) to ensure permanent coupling between clutch drive shaft(109) & PTO drive coupling shaft(120),
wherein said dog clutch(I23) when positioned at maximum extend in forward direction engages said PTO drive coupling(120) & said speed reduction input

shaft(112), whereby the engine power from said clutch drive shaft(109) is transferred to the speed reduction input shaft(l 12), and
wherein said dog clutch(123) is shifted a step backward from the maximum disengages said PTO drive coupling(120), whereby the power from the engine is not transferred to said speed reduction input shaft( 112) while the power take-off coupling shaft is continuously receiving power from said clutch drive shaft(109).
10. The PTO drive shifting system (122) as claimed in claim 9, wherein said PTO coupling(120) has inner diameter provided with splines adapted fixedly to engage with splines(l 17c) at forward end(l 17a) of a PTO coupling shaft(l 17) and outer diameter is provided with splines in similar with sp!ines(109c) at second end of a clutch drive shaft(109) and splines(l 12c) at first end of a speed reduction input shaft(112).
11. The PTO drive shifting system (122) as claimed in claim 10, wherein said dog clutch(123) has a slot(123a) at outer diameter adapted to engage with one end of a PTO lever for comfortably operating said PTO drive shifting system (122).
12. The PTO drive shifting system (122) as claimed in claim 10, wherein a coupling device(125) is provided in a transmission housing(102) to engage and disengage first end(116a) of said PTO input shaft(l 16) with backward end(117b) of said PTO coupling shaft(l 17) as per requirement.