FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
AN ENERGY EFFICIENT HYDRAULIC SYSTEM FOR EFFECTIVE ROUTING OF HYDRAULIC FLUID IN OFF-ROAD VEHICLE SUCH AS TRACTOR
2. APPLICANT(S)
MAHINDRA & MAHINDRA LTD.
GATEWAY BUILDING, APOLLO BUNDER, MUMBAI - 400001, MAHARASHTRA, INDIAN.
The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the Invention
The present invention relates to hydraulic system for off-road vehicles and farm machineries such as tractors. In particular the present invention relates to a system for effectively routing hydraulic fluid flow, controlled lowering of the implement using hydraulic system and obviating problems associated with leakages of hydraulic fluid inside the valve body to enhance effectiveness and efficiency of the hydraulic system and thereby performance of the off-road vehicle such as tractor.
Background of the Invention
Conventional off-road vehicles such as tractors that work in farm land
are provided with hydraulic system for lifting or lowering earth working
implement that is hitched to the three point linkage of the tractor.
Primarily the hydraulic system is utilized to provide
√ necessary force to lift / lower the implement known as hitching operation;
√ steering application of the vehicle; and
√ in adjusting the implement to respond to draft setting so as to overcome aspects of variation of depth of insertion of the implement due to uneven nature of the farm land or obstructions.
The first problems associated with the conventional hydraulic system of the off-road vehicle such as tractor with respect to aforementioned applications are mentioned hereunder in three categories viz.
1. Lack of effective utilization of hydraulic pumps,
2. Problems due to leakage of hydraulic fluid inside pump and
3. Undesirable effects due to lack of hydraulic force in lowering the implement.

The details are as follows:
1. Lack of effective utilization of hydraulic pump/s
The hydraulic system primarily comprises of pump/s and valves. These are positive displacement type pumps predominantly comprising piston and cylinder type construction. The capacity of the pump depends on cylinder volume (in Cubic Centimeter: CC) of the pump and further the amount of hydraulic fluid displaced per unit time by the pump. A tandem pump of higher and lower capacity (CC) or two different pumps of higher and lower CC may be used in the hydraulic system of the tractor. The higher CC pump, conventionally known as hitch pump is used for Hitch function as flow requirement is high. The lower CC pump, conventionally known as steering pump is used for steering application as flow requirement is less for steering application.
The hitching application that includes trolley lifting or implements lifting / lowering through substantial heights demands considerable force and hence comparatively larger hydraulic fluid flow rate from the pump. Further, lifting time is a crucial factor, if flow rate is reduced the time taken for lifting will increase, which will hamper the productivity in that function. Thus, the pump capacity of the hitch pump is substantial.
For draft sensing application, the force requirement is comparatively lower. Therefore the pump capacity is lower. There marginal lifting of the implement required to relieve the momentarily force acted by implement on bell crank of the tractor. Conventionally, hitch pump caters to this need. However, during this operation the pump incurs heavy loss of efficiency as useful flow is very less as compared to available flow pumped by higher CC pump and thus there will be heavy power loss and efficiency will be very less, this will also result in heating of the system.

This is quantitatively explained as follows:
An 18 CC pump will pump 40 liters hydraulic fluid (oil) approx. at rated speed, whereas max flow required during draft operation in only 2 Ipm, thus there will be wastage of power generated by 38 Ipm flow which is drawn from Engine
Further in conventional hydraulics draft sensing will be continuously in sensing mode as there is no provision for shutting off the draft sensing, this causes unnecessary actuation of cylinder when not required. For example, in transporting of implement in lifted condition or any other haulage operation done by using three point linkages, there will be continuous vibration and jerks coming from the implement and this will continuously actuate draft sensing mechanism unnecessarily.
Thus there is a need to effectively route hydraulic fluid flow from the pumps so as to optimize the usage and pumping of the hydraulic fluid that will lead to enhancing energy efficiency of the tractor.
2. Hydraulic fluid leakage inside pump
Conventionally lifting and lowering of implement is governed by a hydraulic control valve, conventionally spool and body arrangement (100) (known as 3-way solenoid operated valve) is used for hitch control valve.
The hydraulic valve comprises of spool that slides inside cylindrical valve body wherein ports / openings are provide at particular locations in the valve body. The disposition of the spool with respect to these ports determines routing of the hydraulic flow. This is illustrated in Figure 1. Clearance is required between spool (101) and body (102)

as spool (101) is required to be moved within body (102). As shown in the Figure la, the clearance may cause leakage from port A to port P.
This results in loss of hydraulic oil in the pressure line (103) of the single acting hydraulic cylinder (104) as shown in the Figure lb. This in turn will result adversely in load carrying capacity of the cylinder. The piston of this cylinder is coupled with the rockshaft of the three point linkages that is hitched with the implement. Forward motion of the cylinder results in raising the implement and vice versa. Needless to state, retraction of the piston due to hydraulic oil leakage leads to undesirable lowering of the implement hitched to the three point mechanism.
It may be noted that if spool clearance is reduced to overcome this internal leakage problem, the problems of spool jamming in the valve body are observed.
During transportation/haulage with implement, the farmer will lift the implement to certain height during travel, but over the course of time in journey the implement will drop for above given reasons. Thus the implement has to be again lifted to overcome the drop in implement, also if unnoticed it may completely drop and cause an accident over a longer journey.
Since in the field / farm it is not possible to identify this internal leakage problem of valve over the period of time, there is need to provide a system that will maintain hydraulic oil pressure in the cylinder in spite of such leakage occurrence.

3. Lack of hydraulic force during implement lowering
Generally tractor hydraulic lifting mechanism is designed to lift the implement by application of hydraulic force. The hydraulic oil flows in only one compartment of the single acting pump cylinder resulting in pushing the piston of the cylinder to operate / rotate the rockshaft so as to lift the implement. The oil is drained from other compartment of the cylinder to the oil reservoir.
Importantly, when operator required to lower the implement the oil in first compartment is let out in the reservoir resulting in retraction of the piston. However, it is important to note that the load (that is weight) of implement acting downwards results in retraction of the cylinder piston. Thus drop rate of implement will be proportional' to the implement weight, higher the load higher will be the drop rate. This is in a way passive lowering independent of external energy consumption (in terms of hydraulic oil pumping). This imposes critical limitation such that there is no control on the rats and extent of lowering. Further since the implement cannot be used for self jacking of the tractor in which case implement bears the load of the rear part of the tractor to lift rear wheels.
There is a need to provide a hydraulic system to enable hydraulic actuated controlled lowering of the implement actively.
Summary of the Invention
The main object of the invention is to provide effective and energy efficient hydraulic system for effectively routing hydraulic fluid flow, controlled lowering of the implement using hydraulic system and obviating problems associated with leakages of hydraulic fluid inside the valve body to enhance effectiveness and efficiency of the hydraulic

system and thereby performance of the off-road vehicle such as tractor.
Another object of the invention is to provide optimized routing of the hydraulic fluid flow from pumps for field operation/s and steering. Further object is to provide low flow from steering pump to hitch
cylinder during field operations like ploughing thereby improving fuel efficiency of tractor
Further object of the invention is to provide a controller.
Further object of the invention is to provide a process of operation of the hydraulic system.
Further object of the invention is to reduce auxiliary power consumption of the off-road vehicle such as tractor.
Further object of the invention is to reduce overheating of prime mover during field operations by pumping only the required flow to cylinder.
Further object of the invention is to increase pump life and reduce life cycle cost by eliminating continuous loading from higher CC pump during field operations
Further object of the invention is to provide a system to obviate undesirable actuation of cylinder/draft sensing.
Another object of the invention is to provide a system to obviate problems of drop of the implement due to internal hydraulic oil leakage in the control valve.

Another object of the invention is to provide a system for hydraulic actuated lowering, lowering control and provision for self jacking of the tractor.
Further object of the invention is to provide depth control of the implement in field operations and reduce damping effect in implement transportation.
Thus in accordance with the invention the system comprises of a valve
block assembly, a microprocessor based controller;
double acting hydraulic cylinder configured with a check valve, pilot
piston valve;
wherein
the said valve block assembly comprises of position control solenoid
valve, draft control solenoid valve, compensator valve that are
electronically configured with the said controller wherein the said
position control and draft control valves are four way three position
type solenoid operated hydraulic valves wherein the said compensator
valve is a pressure and / or flow regulating type hydraulic valve
wherein
the said valve block assembly is hydraulically configured with the hitch
pump, steering pump, cylinder that is operably coupled with the
rockshaft to which implements are hitched
Description of the Invention
Features and advantages of this invention will become apparent in the following detailed description and the preferred embodiments with reference to the accompanying drawings.

Figure 1 Schematic of the prior art system (Sheet 1)
Figure 1c Schematic of system configuration (Sheet 1)
Figure 2 Schematic of the compensator valve (Sheet 2)
Figure 3 Layout of the valve block (Sheet 2)
Figure 4 Configuration of the valve block during implement lifting
(Sheet 3) Figure 5 Configuration of the valve block during implement lowering
(Sheet 3) Figure 6 Configuration of the valve block during draft sensing
(Sheet 4) Figure 7 Configuration of the valve block (Sheet 4) Figure 8 Schematic of the hydraulic configuration (Sheet 5) Figure 9 Schematic of the hydraulic configuration (Sheet 5) Figure 10 Schematic of self jacking of tractor (Sheet 6)
The configuration of the said valve block assembly 1 and controller 19 with various components of the tractor is illustrated in the Figure lc.
As illustrated in the Figure lc, the valve blocklcomprises of a compensator valve 2, position control solenoid valve 3 and draft control solenoid valve 4.
As illustrated in lay out of the valve block in Figure 3, it further comprises of two input ports, Hitch pump port 5 and steering pump port 6to receive the pumped hydraulic fluid from the respective pumps of the tractor. Further there are four output ports viz. lifting port 7 and lowering port 8 connected to the double acting hitch cylinder of the tractor, steering output port 9connected to the steering of the tractor and return line lOthat is connected to the hydraulic fluid reservoir (not shown).

The said valve blocks enables effectively routing hydraulic fluid flow so as to optimize operation of steering as well as hitch pump. The various stages of this operation are explained as follows:
√ As illustrated in Figure 3, in neutral condition (that is the cylinder is not operated to lift / lower the implement), the hitch pump 24 flow will passes from port 5 to the said position control solenoid 3 and further to the return line 10 (this path is indicated by a red colored line);
√ As illustrated in Figure 4,during the implement lifting (implement not shown) operation the hitch pump flow is routed from port 5 to the position control solenoid valve 3 to the lifting port 7 and further to the said cylinder so as to displace piston for outward stroke (this path is indicated by a red colored line);
√ As illustrated in Figure 5, during implement lowering (implement not shown) operation the hitch pump flow passes from the port 5 to the position control valve 3 to be routed to the lowering port 8 and further to the said cylinder so as to retract the piston (this path is indicated by a red colored line)
Figure 2 illustrates construction of the compensator valve 2. It comprises of a sleeve 11, spool 12, spring 13, spring washer 14, closure plug 15, o-ring 16 and orifice 17. The compensator valve 2 operates to supply a fixed flow (constant volume flow rate) to the draft control valve 4.
As illustrated in Figure 3, during neutral operation the hydraulic fluid (substantially lower volume flow rate compared to the pumped from the hitch pump)pumped by the steering pump passes from port 6 and is split in two passages at junction 18. The first stream passes through orifice 16 into the sleeve 11 over the spool 12 into the draft control solenoid valve 4 and further to the return line 10. The second stream

passes through sleeve 11 over the spool 12 and further to the steering output port 9.
The inventive aspect of the present invention is to be noted in that the said draft control solenoid valve 4 can be operated / actuated to divert / route the fixed hydraulic fluid flow from the said steering pump 25 to the lifting port 7 or lowering port 8 to enable draft sensing which is otherwise is not the case in conventional system that use higher flow from the hitch pump 24 for draft sensing resulting in underutilization of the pump capacity leading to energy inefficient operation.
With reference to Figure 1 the configuration and functional interrelation of the said valve block 1 with the controller 19 and the draft sensing / setting system of the tractor is explained as follows:
√ the controller 19 receives signal from the draft sensing potentiometer 20 and draft setting potentiometer 21 of the tractor;
√ the controller 19 compares values from setting pot 20 and actual pot 21 and accordingly, depending on the positive or negative difference between input values it gives signal to said direction control solenoid valve 4 of the said valve block assembly 1 to divert / route the flow to lifting port 7 or lowering port 8 respectively;
√ It is to be noted that unless draft selection mode 22 of the tractor is in operation / actuated, the said valve 4 will always be in neutral condition and actuation of the valve 4 would not take place even if there is difference between the values of the signals from potentiometers 20 and 21;
√ Thus the operator has to initiate / select the draft selection mode 22 to use low flow from steering pump 25 for field operations like ploughing.

The said draft control valve 4 is configured with the controller 19 and it operates based on the activation from the said controller to divert the (low) flow from the said steering pump to the cylinder for the draft sensing purpose, following are the details of this operation:
√ If the difference between setting pot 20 and actual pot 21 is negative the controller 19 sends signal to the valve 4 to divert the available compensated flow to lifting port 7 as illustrated in Figure 6 (the pressurized flow path is indicated by red lines)
√ Further, if the difference between setting pot 20 and actual pot 21 is positive, the controller 19 sends signal to the direction control solenoid 4 to divert / route the available compensated flow from the valve 2 to lowering port 8 as illustrated in Figure 7 (the pressurized flow path is indicated by red lines)
The system of the present invention provides solution for obviating problems associated with leakages of hydraulic fluid inside the valve body that results in undesirable and uncontrollable drop of the hitched implement.
As illustrated in Figure 8, this system comprises of a check valve 26 and pilot piston valve 27 between lift cylinder (Double acting cylinder) and the position control valve (4 way three position solenoid operated valve). The check valve 26 comprises of seat 28 and ball 29.
The operation of this system during lifting of the implement is explained as follows with reference to the Figure 8:
√ In operation the hydraulic fluid (oil) flows from hitch pump 24 to check valve 26. The pressurized oil passes through seat 28 and pushes ball 29 outwards which allows the oil to flow further to pilot pressure valve 27.The pressurized oil further pushes ball 30

against seat 31 thus restricting the flow to pass further from pilot piston valve 27. Thus now the oil can only pass further through passage 32 into lift cylinder for lifting cycle.
√ Once cylinder is lifted for desired position, and system is neutral the oil is retained in the said lift cylinder. The oil cannot pass to the said position control valve as in the check valve 26 the ball 29 will be pushed against seat 28 thus restricting the flow to pass further.
√ In pilot piston valve 27 as well oil is trapped in cylinder. Even while transporting if pressure increase in lift cylinder, it will further push both balls (29 & 30 ) against their respective seats (28 & 31) with high pressure, thus providing almost zero drop when cylinder is in lifting cycle.
The operation of the system during implement lowering cycle is explained as follows with reference to the Figure 9:
√ when the cylinder is required to be lowered (that is the piston is to be retracted) the oil present in backward compartment 33 of the lift cylinder is to be unloaded, this is possible by providing pilot piston valve 27 and double acting cylinder in this system i.e. forced lifting and forced lowering whereas conventional tractor hydraulic systems are forced lifting and gravity lowering;
√ In lowering cycle the oil pumped from pump 24 through the piston control valve 27 to passage 34 to forward compartment 35 of the lift cylinder;
√ As shown in the Figure, from passage 34, a pilot line 35 is connected to pilot piston valve 27, thus oil flows to passage (34 & 35) simultaneously
√ Pressure develops on area of pilot piston 36 resulting moving the pilot piston 36 and opening the ball 30, against the force acting on the ball 30 from other side;

√ even if same pressure are acting on both sides the force generated by pilot piston 36 will be higher as area of ball 30 is less compared to that of pilot piston 36;
√ Upon pushing of the ball 30, the oil from lift cylinder compartment 33 will unload through passage 32 to pilot piston valve 27 to lowering control valve 37 and further to the position control valve to return line, thus oil from lift cylinder compartment 33 is unloaded and simultaneously oil in lift cylinder compartment 35 will be filled completing the lowering cycle;
√ The lowering control valve 37 is a flow regulating valve to regulate return line flow, thus controlling the drop rate in return line 38. This facilitates to control the speed of lowering the implement
In one of the embodiments single acting cylinder is used in the present invention. The person skilled in the art could contemplate configuration of such cylinder in the system.
The system of the present invention uses double acting cylinder. Both the sides of the piston are used for hydraulic oil displacement. These are illustrated in Figure 9 (compartment 35 and 33). Thus the operations of lifting of the implement (wherein the piston is pushed out) as well as lowering of the implement (wherein the piston is retracted) are hydraulically actuated i.e. lifting and lowering is done with the aid of hydraulic force. This provides close control on the said operations as well as enables pre-setting of the extent of lifting or lowering.
The forced and controlled lowering of the implement enables holding the implement position without variation. Thus depth of cut in field operations can be maintained. On the contrary, in conventional system the implement is free to lift after given depth of cut as other side of

cylinder is open to tank refer which can cause the implement to lift in undulations of ground, this will not happen in new concept as it is not free to lift as hydraulically the position is locked for lifting as well as lowering. This aspect is extremely useful and productive in field operations such as leveling wherein maintaining uniform depth of cut is essential intent.
The use of double acting cylinder in the present invention enables dampens vibrations. During transportation of implement in haulage operation, it generates tension and compressive forces on mechanical parts of three point linkage and hydraulic power train which is caused by movement and vibration of implement during transport. In conventional tractor hydraulic system the compressive forces will get dampen as oil will be present in one of the compartments of cylinder, while there will be no damping provided from the other compartment as it is open to tank. Since double acting cylinder is used in the present invention wherein the hydraulic oil is present on both the sides of piston (both the compartments), damping effect for both tensile and compressive forces is provided to cater to the vibrations and movement of the implement during transportation of the tractor.
The system of the present invention facilitates self jacking of the tractor with the aid of forced hydraulic lowering of the implement. This operation is illustrated in Figure 10. As shown in the Figure, in conventional tractor, the lower links 40 of the tractor are attached to lift arms 41 by means of lift rods 42. It can be noted that once lower link 40 is in contact with the ground (support surface), its movement stops as it is lowered by gravity and there is no externa! force acting / applied on this fink. The use of forced lowering in the system of the present invention enables application of downwards force on the said lower link 40even when it is in contact with the ground. This is possible due to presence of pressurized hydraulic oil in both the compartments

of the cylinder. As illustrated in the Figure, this forced lowering is used to self jack the tractor wherein rear wheels are lifted from the support surface. This enables various operations like tyre change, inspection, maintenance etc without use of external jack for lifting of tractor in the field /farm.
Thus it is evident from the present invention that the synergistic combination of the valve block, check valve, double acting cylinder that are configured with the controller provide effective and energy efficient hydraulic system that enables routing hydraulic fluid flow, obviates problems associated with leakages of hydraulic fluid inside the valve body to enhance effectiveness and efficiency of the hydraulic system and thereby performance of the off-road vehicle such as tractor

We claim:
1. An energy efficient hydraulic system in off-road vehicle comprising a valve block assembly (1), a controller (19), double acting hydraulic cylinder of the off-road vehicle configured with a check valve (26), pilot piston valve (27); wherein
the said valve block assembly comprises of position control solenoid valve (3), draft control solenoid valve (4), compensator valve (2) that are electronically configured with the said controller (19) wherein the said position control and draft control valves are four way three position type solenoid operated hydraulic valves wherein the said compensator valve is a pressure and / or flow regulating type hydraulic valve; wherein
the said valve block assembly is hydraulically configured with the hitch pump (24), steering pump (25), cylinder that is operably coupled with the rockshaft to which implement/s of the off road vehicle such as tractor are hitched to enable effective routing of hydraulic flow to enhance effectiveness and efficiency of the hydraulic system and thereby performance of the off-road vehicle such as tractor.
2. An energy efficient hydraulic system as claimed in claim 1 wherein the said valve block assembly (1) comprises two input ports, hitch pump port (5) and steering pump port (6) to receive the pumped hydraulic fluid from the respective pumps of the tractor;
four output ports as lifting port (7) and lowering port (8) connected to the double acting hitch cylinder of the off road vehicle such as tractor, steering output port (9) connected to the

steering of the off road vehicle such as tractor and return line (10) that is connected to the hydraulic fluid reservoir.
3. An energy efficient hydraulic system as claimed in claim 1
wherein the compensator valve (2) comprises of a sleeve (11) in
which the spring (13) loaded, spool (12) is operably fitted, spring
washer (14), closure plug (15), O-ring (16) and orifice (17);
wherein the compensator valve operates to supply a constant volume flow rate to the draft control valve (4) to be actuated to divert / route the fixed hydraulic fluid flow from the said steering pump (25) to the lifting port (7) or lowering port (8) to enable draft sensing which is otherwise is not the case in conventional system that use higher flow from the hitch pump (24) for draft sensing resulting in underutilization of the pump capacity leading to energy inefficient operation.
4. An energy efficient hydraulic system as claimed in claims 1, 2
wherein the said valve block assembly operates during the
neutral condition wherein the double acting hitch cylinder of the
off road vehicle such as tractor is not operated to lift / lower the
implement wherein the fluid flow from the hitch pump (24) is
routed from port (5) to the said position control solenoid (3) and
further to the return line (10).
wherein during this neutral operation the hydraulic fluid with substantially lower volume flow rate compared to the pumped from the hitch pump is pumped by the steering pump and is routed from port (6) to split in two streams at junction (18), the first stream is routed through orifice (17) into the said sleeve (11) over the said spool (12) into the draft control solenoid valve (4) and further to the return line (10), the second stream passes

through sleeve (11) over the spool (12) and further to the steering output port (9).
5. An energy efficient hydraulic system as claimed in claims 2, 4 wherein the said valve block assembly operates during the implement lifting operation wherein the fluid flow from the hitch pump is routed from port (5) to the position control solenoid valve (3) to the lifting port (7) and further to the said cylinder so as to displace piston for outward stroke.
6. An energy efficient hydraulic system as claimed in claims 4, 5 wherein the said valve block assembly operates during implement lowering operation wherein fluid flow from the hitch pump is routed from the port (5) to the position control valve (3) to be routed to the lowering port (8) and further to the said cylinder so as to retract the piston of the said double acting hitch cylinder.
7. An energy efficient hydraulic system as claimed in claim 1 wherein the said valve block (1) is configured with the said controller (19) and the draft sensing / setting system of the off road vehicle such as tractor to operate wherein
√ the controller (19) receives signal from the draft sensing potentiometer (21) and draft setting potentiometer (20) of the tractor;
√ the controller (19) compares values from setting potentiometer (20) and actual potentiometer (21) and accordingly, depending on the positive or negative difference between input values sends signal to the said draft control solenoid valve (4) of the said valve block assembly (1) to

divert / route the flow to lifting port (7) or lowering port (8) respectively;
√ prohibit the actuation of the said valve (4) unless draft selection mode (22) of the tractor is in operation even if there is difference between the values of the signals from potentiometers (20 and 21) wherein the operator has to initiate / select the draft selection mode (22) to use low flow from steering pump (25) for field operations like ploughing.
8. An energy efficient hydraulic system as claimed in claims 1-7 wherein the said draft control valve (4) is configured with the controller (19) to operate based on the activation from the said controller to divert the substantially lower volume flow rate of fluid from the said steering pump to the said double acting cylinder for the draft sensing purpose wherein
√ in case the difference between setting potentiometer (20) and actual potentiometer (21) is negative, the controller (19) sends signal to the valve (4) to divert the available compensated flow to lifting port (7) (Reference: Figure 6);
√ in case the difference between setting potentiometer (20) and actual potentiometer (21) is positive, the controller (19) sends signal to the direction control solenoid (4) to divert / route the available compensated flow from the valve (2) to lowering port (8) (Reference: Figure 7)
9. An energy efficient hydraulic system as claimed in claim 1 wherein the system to obviate leakages of hydraulic fluid inside the valve body comprising a check valve (26) and pilot piston valve (27) between the said double acting cylinder and the position control valve, wherein the check valve (26) comprises of

seat (28) and ball (29) wherein during operation (Reference: Figure 8)
√ the hydraulic fluid (oil) is routed from hitch pump (24) to check valve (26) so that the pressurized oil passes through seat (28) and pushes ball (29) outwards which allows the oil to flow further to pilot pressure valve (27); the pressurized oil further pushes ball (30) against seat (31) thus restricting the flow to pass further from pilot piston valve (27) to ensure that the oil can only pass further through passage (32) into lift cylinder for lifting cycle;
√ once cylinder is lifted for desired position, and system is neutral the oil is retained in the said lift cylinder wherein the oil cannot pass to the said position control valve as in the check valve (26) the ball (29) will be pushed against seat (28) thus restricting the flow to pass further;
√ in pilot piston valve 27 as well the fluid is trapped in cylinder wherein while transporting if pressure increase in lift cylinder, it will further push both balls (29 & 30 ) against their respective seats (28 & 31) with high pressure, thus providing almost zero drop when cylinder is in lifting cycle obviating undesirable and uncontrollable drop of the hitched implement.
10. An energy efficient hydraulic system as claimed in claims 1, 9wherein the system during implement lowering cycle operates (Reference: Figure 9) wherein,
√ when the cylinder is required to be lowered (that is the piston is to be retracted) the oil present in backward

compartment (33) of the lift cylinder is to be unloaded, with the aid of pilot piston valve (27) and the said double acting cylinder in this system to achieve forced lifting and forced lowering;
√ in lowering cycle the fluid from pump (24) is routed through the piston control valve (27) to passage (34) to forward compartment (35) of the lift cylinder;
√ from passage (34), a pilot line (35) is connected to pilot piston valve (27), thus oil flows to passage (34 & 35) simultaneously;
√ pressure develops on area of pilot piston (36) resulting moving the pilot piston (36) and opening the ball (30), against the force acting on the ball (30) from other side;
√ in case same pressure acts on both sides, the force generated by pilot piston (36) is higher as area of ball (30) is less compared to that of pilot piston 36;
√ upon pushing of the ball (30), the oil from lift cylinder compartment (33) will unload through passage (32) to pilot piston valve (27) to lowering control valve (37) and further to the position control valve to return line , thus oil from lift cylinder compartment (33) is unloaded and simultaneously oil in lift cylinder compartment (35) will be filled completing the lowering cycle;
√ the lowering control valve (37) is a flow regulating valve to regulate return line flow, thus controlling the drop rate in return line 38 to enable control of the speed of lowering the implement.
11. An energy efficient hydraulic system as claimed in claim 1 wherein self-jacking of the off road vehicle such as tractor is enabled with the aid of forced hydraulic lowering of the implement wherein forced lowering enables application of

downwards force on the said lower link 40 even when it is in contact with the ground (Reference: Figure 10) due to presence of pressurized hydraulic oil in both the compartments of the said double acting cylinder.
12. An energy efficient hydraulic system as claimed in claims 1-11 wherein one or plurality of single acting cylinder/s is/ are used.