FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
& The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A hydraulic jack system for providing variable mechanical advantage to an operator
APPLICANT
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030,
Maharashtra, India, an Indian Company
INVENTOR
Khedkar Parag Prabhakar of S3 Division. Switchgear Complex, Crompton Greaves Ltd, Ambad,
Nashik. Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
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 generally to hydraulic jack systems that provides
variable mechanical advantage to an operator.
DESCRIPTION OF THE BACKGROUND ART
A jack system is one of the common tools used in our daily life to lift a load for a
preset lift distance with less manual force applied by an operator than the force required to lift it directly. The jack system operated by hydraulic pressure comprises a pump having an input piston which has a small cross-sectional area to move with a small force, pushes the hydraulic oil into the output cylinder, thus driving the output piston, which has a larger surface area to lift the load.
Hydraulic jack systems are typically used in many applications such as pallet
truck, scissor'lifts, jacks for cars and trucks, hydraulic press, crimping tools, pullers, and also for lifting heavy equipments. In most of these operations, hydraulic jack systems with manual pumping arrangement are used. Hydraulic jack system with manual pumping arrangements has its own limitations though. A typical Hydraulic jack system comprises a pump, cylinder, oil tank, a handle to operate the pump and piping for the oil. The jack has two non return valve and a hand operated valve. When the handle is moved down the piston rod is pressed downwards and the piston pressurizes the oil. Due to increased pressure the oil moves in the cylinder and in turn pushes the piston upwards. When the handle is raised the spring in the pump raises the piston reducing the pressure even below atmosphere this makes the oil to flow in the pump. When the handle is pressed again the one way valve do not allow the oil to go back to oil tank. This is how the piston rod of the cylinder is pushed upwards as the oil keeps entering the cylinder. When the

hand operated valve is opened the oil flows back to tank and the piston rod is pushed downward due the load which it has lifted.
The mechanical advantage offered by any hydraulic jack is the ratio of the
maximum force it can generate and the force exerted by the operator. For any jack this is also equal to the ratio of the cross-sectional area of the jack piston and the pump piston. The higher the mechanical advantage, the lower will be the speed of the jack. The mechanical advantage (and the speed) is fixed for any jack. This high mechanical advantage is desirable when the jack is lifting maximum load. However when lower loads are lifted or the jack is only being expanded (opened at no load) this mechanical advantage is undesirable because of it inherent low speed. Similarly when the jack is being used for pressing a spring the force increases slowly from zero to maximum, in such situation also the fixed slow speed becomes a disadvantage. There exists no direct solution of the problem. In this scenario to increase the speed, pump size is to be increased, which results in application of more force by the operator. If this type of the actuator is used for pressing a spring the load will vary as the spring will be compressed. Initially it will be less and then it will increase. This type of actuator will not allow pressing the spring faster initially and then slowly as the load increases. This is an inefficient way of operating. The operator fatigue increases due to increased number of strokes. Additionally, a lot of time is also consumed in engaging the piston with the load,
Thus, there is a need to provide an improved hydraulic actuation system that
overcomes at least some of these disadvantages.
SUMMARY OF THE INVENTION
Accordingly disclosed herein is a hydraulic jack system for providing variable
mechanical advantage to an operator during operation including a jack assembly, a jack piston

disposed within a cylinder, the jack piston openable outwardly from the jack cylinder to lift a load, the jack assembly connected to an oil reservoir through a manually operated control valve, a pump connected to the oil reservoir through a withdrawing conduit for receiving oil when the pump exerts a suction stroke, the pump connected to the jack cylinder through a dispensing conduit for dispensing the received oil within the jack cylinder when the pump exerts a compression stroke, a lever pivotally engaged within a slot of a support structure and positioned at an end of the slot formed within the support structure, the lever angularly displaceable along a vertical plane to allow the pump to exert the suction and compression stroke, pivotable end of the lever capable of being slidably movable to an opposite end of the slot, and an additional piston-cylinder arrangement securely held within a jack frame and connected between the jack cylinder and the pump through corresponding conduits, free end of the piston having a flange member fixedly connected to the pivotable end of the lever, wherein when the piston expands the pivotable end of the lever slides to the opposite end of the slot.
According to some embodiments, when load on the jack piston increases a portion
of the oil present within the jack cylinder is dispensed within the cylinder of the additional piston-cylinder arrangement thereby allowing the piston of the additional piston-cylinder arrangement to be expanded.
According to some embodiments, the support structure is positioned in between
the pump and the additional piston-cylinder arrangement, the slot formed adjacent to top surfaces of the support structure.
According to some embodiments, an intermediate conduit is connected with the
jack cylinder and extends to be connected with the cylinder of the additional piston-cylinder arrangement.

According to some embodiments, the hydraulic jack system according to claim 1,
wherein the lever is shifting of the pivotable end of the lever on the opposite end of the slot allows the effective length between the pump and the pivotable end thereby increasing the mechanical advantage offered to the operator.
It is to be understood that both the foregoing general description and the
following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.
A BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of the various
embodiments of the invention, and the manner of attaining them, will become more apparent and will be better understood by reference to the accompanying drawings, wherein:
FIG. 1 is a front elevational view of a hydraulic jack system having a first pump
and a second pump exerting a suction stroke according to an embodiment of the present
invention;
FIG. 2 is a front elevational view of the hydraulic jack system of FIG. lhaving the
first pump and the second pump exerting a compression suction stroke;

FIG. 3 is a front elevational view of a hydraulic jack system having an additional
piton-cylinder arrangement in closed position according to another embodiment of the present invention;
FIG. 4 is a top view of a mechanical arrangement between the additional piston-
cylinder arrangement of FIG. 3 and a pivotable end of a lever of according to an embodiment of the present invention; and
FIG. 5 is a front elevational view of the mechanical arrangement of FIG. 4
supported over a support structure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates a hydraulic jack system 100 according to an embodiment of the
present invention. The hydraulic jack system 100 includes a jack assembly 102 that has a jack piston 104 disposed within a jack cylinder 106. The jack piston 104 has got the tendency to open outside from the jack cylinder 106 when a pushing force is applied on a bottom surface of the jack piston 104. The jack piston 104 is openable outwardly from the jack cylinder 106 to lift a load (not shown) that may be associated with an off-road or an on-road vehicle. The jack assembly 102 is connected to an oil reservoir 108 through a manually operated control valve 110. Preferably, the control valve 110 is a manually operated non-return valve 136. However, simitar devices would also be considered to be within the scope of the present invention. The oil reservoir 108 should be appropriately designed so that the size of the overall jack system 100 does not increase and portability is maintained.
As seen in FIGS. I and 2, the jack system 100 also includes a first small sized
pump constructed to have a reciprocating piston 114 disposed within the first pump cylinder 116.

Preferably, the first pump 112 is disposed along a vertical plane of the hydraulic jack assembly 102. Further, a biasing member, preferably a spring 118 is positioned between the piston 114 and the cylinder 116 of the first pump 112. The spring 118 is located below piston 114 in the cylinder 116. Furthermore, when the first pump 112 is in operation the piston 114 exerts a compression stroke and a suction stroke. The cylinder 116 of the first pump 112 is connected to the oil reservoir 108 through a first withdrawing conduit 120 for receiving oil. The cylinder 116 is also connected to the jack cylinder 106 through a first dispensing conduit 122. It is to be understood that when the first pump 112, in operation, exerts a suction stroke, due to the suction pressure exerted between the piston 114 and the bottom portion of the cylinder 116, oil from the oil reservoir 108 rushes to occupy the empty space therein. Further, when the first pump 112 exerts a compression stroke, the received oil within the cylinder 116 of the first pump 112 is dispensed outside and reaches within the jack cylinder 106 via the first dispensing conduit 122.
The jack system 100 further includes a second pump 124 constructed to have a
reciprocating piston rod 126 disposed within the second pump cylinder 128. Preferably, the second pump 124 is also disposed along the vertical plane and adjacent to the first pump 112. Preferably.- the dimensions of the second pump 124 are chosen in such a manner that its size is, preferably, at least three times greater than the size of the first pump 112. However, the dimensions of the second pump 124 may be more or less than the three times than the size of the first pump 112 and should be construed to be within the scope of the present invention. Further, similar to the first pump 112, the second pump 124 also includes a biasing member, for example the spring 118, located inside the cylinder 128 below piston rod 126 within the second pump 124. Furthermore, similar to that of working of the first pump 112 when the second pump 124 is in operation the piston rod 126 exerts a compression stroke and a suction stroke. The cylinder

128 of the second pump 124 is connected to the oil reservoir 108 through a second withdrawing conduit 130. The cylinder 128 of the second pump 124 is also connected to the jack cylinder 106 through a second dispensing conduit 132. It is to be understood that when the second pump 124, in operation, exerts a suction stroke due to the suction pressure exerted between the piston rod 126 and the bottom portion of the cylinder 128, oil from the oil reservoir 108 rushes to occupy the empty space therein through the second withdrawing conduit 130. Further, when the second pump 124 exerts a compression stroke, the received oil within the cylinder 128 of the second pump 124 is dispensed outside and reaches within the jack cylinder 106 via the second dispensing conduit 132.
As seen in FIGS. 1 and 2, the cylinders 106, 128 of the jack cylinder 106 and the
second pump 124, respectively, are interconnected through an intermediate conduit 134, preferably through a high pressure line. During operation, the oil is dispensed within the second pump, through the intermediate conduit, on top of a second piston rod when the oil pressure in the jack cylinder increases to such a level that the force generated by dispensed oil on the second piston of the second pump is more than the force of the spring, the dispensed oil allowing the piston rod to be pushed downward gradually thereby making the second the pump redundant, Initially the stroke reduces and then become zero. As a result of this progressive load building on top of the piston 126 within the cylinder 128 of the second pump 124, the piston 126 progressively starts moving towards the bottom portion of the cylinder 128 against the spring 118 and reaches to a state of a permanent compression stroke. Furthermore, as seen in FIGS. I and 2, each of the first and second withdrawing conduits 12,0, 130 and each of the first and second dispensing conduits 122, 132 having a non-return valve 136 connected thereto. Preferably, the intermediate conduit is designed in such a manner that when the second pump

126 is operated initially, major portion of the received oil is dispensed into the jack cylinder 106. However, when the load starts building up on the jack piston 104 more and more amount of the dispensed oil is received on top of the piston 126 within the second pump 124. The high pressure line is designed accordingly to take care of this operation.
Again referring to FIGS. 1 and 2, a longitudinal lever 138 is pivotally connected
to a hydraulic jack frame (not shown). Preferably, the lever 138 is suitably connected to opposite inner surfaces of the jack frame to efficiently provide pivotal motion. Further, the lever 138 is positioned in such a manner that the lever 138 engages top surfaces 140 of the piston rods of the both the first pump 112 and the second pump 124. respectively, when the first pump 112 and the second pump 124 are performing their corresponding suction and compression strokes. In order to have an efficient operation, the lever 138 makes a point contact with the piston rods of both the first pump 112 and the second pump 124. Therefore, according to one embodiment of the present invention, the contacting top surfaces 140 of both the pistons 114, 126 are of hemispherical shape so that iever 138 makes point contact with the respective surfaces. However, in various other embodiments, the first pump 112, the second pump 124, and the lever 138 may be disposed along a horizontal plane of the jack assembly 102 and construed to be within the scope of the present invention.
Due to this arrangement, the lever 138 when Angularly actuated simultaneously
allows pistons of the first and the second pumps 112, 124, respectively, to exert the suction and compression strokes. So, once both the first and the second pump 124 starts operating and as a result of their simultaneous suctions strokes, a considerable amount of oil is siphoned from the oil reservoir 108 During the simultaneous compression strokes, the oil from both the pumps 112 and 124 will flow to cylinder 106. As a result of this filling, the jack piston 104 starts moving

upside to open outside from the jack cylinder 106. It will be appreciated by a skilled person because of the sizes of the first and the second pump 124, considerably more amount of oil is dispensed within the jack cylinder 106 as compared to the prior art. In this case, approximately four times than the prior art, the dispensed oil could be received within the jack cylinder 106. Thus, a major benefit of positioning the second pump 124 within the hydraulic jack system 100 is to pump in more amount of oil within the jack cylinder 106 that would eventually result in faster opening out of the jack piston 104 from the jack cylinder 106. However, in various other embodiments, depending upon load and time requirements, the second pump 124 may be designed to have dimensions four times or more than the first pump 112 and construed to be within the scope of the present invention.
With respect to the second pump 124 and as noted above, when the hydraulic jack
system 100 is operating, the load on the piston of the second pump 124 increases. Due to this, the high pressure oil slowly presses the piston of the second pump 124 downward against the spring 118, hence when the lever will be raised by the operator the piston of the second pump 124 will not be raised. This will initially reduce the stroke of the second pump 124, however later it wilt make second pump 124 redundant. Only the small pump will be operated and hence the effort required by the operator will reduce thereby giving the operator mechanical advantage. On the contrary when the load reduces, the oil pressure will also reduce and the piston rod of the second pump 124 will again touch the handle.
FIG. 3 illustrates a hydraulic jack system 200 according to another embodiment of
the present invention. The hydraulic jack system 200 includes a jack assembly 202 that has a jack piston 204 disposed within a jack cylinder 206. The jack piston 204 has got the tendency to open outside from the jack cylinder 206 when a pushing force is applied on a bottom surface of

the jack piston 204. The jack piston 204 is openable outwardly from the jack cylinder 206 to lift a load (not shown) that may be associated with an off-road or an on-road vehicle. The jack assembly 202 is connected to an oil reservoir 208 through a manually operated control valve 210. The oil reservoir 208 should be appropriately designed so that the size of the overall jack system 200 does not increase and portability is maintained.
Further, as seen in FIG. 3, the jack system 200 includes a pump 212 constructed
to have a reciprocating piston 214 disposed within a cylinder 216. Preferably, the pump 212 is disposed along a vertical plane of the hydraulic jack system. The size of the pump 212 is made sufficiently large preferably, twice the size of prior art pumps for the same load consideration. However, in various other embodiments, depending upon load and time requirements, the pump 212 may be designed to have dimensions four times or more and construed to be within the scope of the present invention. Further, a spring 218 is also connected to a lower surface 220 of the piston 214 and extends to contact a bottom portion 222 of the cylinder 216. Furthermore, when the pump 212 is in operation the piston 214 exerts a compression stroke or a suction stroke. The cylinder 216 of the pump 212 is also connected to the oil reservoir 208 through a withdrawing conduit 224 for receiving oil. The cylinder 216 is also connected to the jack cylinder 206 through a dispensing conduit 226. It is to be understood that when the pump 212, in operation, exerts a suction stroke due to the suction pressure exerted between the piston 214 and the bottom portion 222 of the cylinder 216, oil from the oil reservoir 208 rushes to occupy the empty space therein. Further, when the pump 212 exerts a compression stroke, the received oil within the cylinder 216 of the pump 212 is dispensed within the jack cylinder 206 via the dispensing conduit 226. Each of the withdrawing conduit 224 and dispensing conduit 226 has the non-return valve 228 connected thereto for performing known functions.

As seen in FJG. 3, an additional piston-cylinder arrangement 230 is securely held
within the jack frame (not shown) and preferably held horizontally against a spring (not shown). The additional piston-cylinder arrangement 230 is connected between the jack cylinder 206 and the pump 212 through corresponding conduits 232. A piston 234 within the additional piston-cylinder has one end 236 that is disposed within the cylinder whereas the opposite end 238 of the piston 234 is relatively free. As seen in FIGS. 4 and 5, the free end 238 of the piston has a flange member 240 fixedly connected thereto. Preferably, as shown in FIG. 5, a support structure 242 is positioned in between the pump 212 and the additional piston-cylinder arrangement 230 within the hydraulic jack frame (not shown). The support structure 242 has a slot 244 formed therein that is linearly positioned with respect to the free end 238 of the piston 234.
Furthermore, as seen in FIG. 3, a lever 246 is also provided within the hydraulic
jack system. The lever 246 is pivotally connected 248 to the flange member 240 to which the free end 238 of the piston 234 of the additional piston-cylinder is connected. Further, the lever 246 is positioned in such a manner that the lever 246 engages the top hemispherical surface 250 of the piston 214 of the pump 212. The pivotable connection 248 of the lever 246 with the flange member 240 is position within the slot 244 on the left most end of the slot 244. The lever 246 may be angularly actuated in a vertical plane. During the suction stroke, a considerable amount of oil from the oil reservoir 208 is siphoned. Further, during the compression stroke, the received oil is dispensed within the jack cylinder 206 and fills the available space within therein. As a result of this filling, the jack piston 204 starts moving upside to open outside from the jack cylinder 206.
However, as the load increases on the jack piston 204 of the jack cylinder 206, the
oil within the jack cylinder 206 rushes to fill in the space within the cylinder of the additional-

cylinder arrangement 230, As a result of this, the piston starts to open up and extend towards right side of the jack assembly 202. The mechanical advantage provided by the lever 246 is nothing but the ratio of Length (LI) of the lever 246 and distance between the pump 212 and the rear end of the lever 246 (L2) (See FIG. 5). As the pivot 248 moves towards right towards the opposite end of the slot, the dimension i.e. distances between the pump 212 and the rear end of the lever 246 reduces increasing the mechanical advantage to the operator. Due to this, the effective stroke length within the pump 212 decreases resulting in pumping in less oil at high pressure.
As the load reduces the spring (not shown) pushes the pivot 248 towards left and
the mechanical advantage reduces as distance between the pump 212 and the rear end of the lever 246 increases. This increases the quantity of oil being pumped (at low pressure) and hence the actuator moves faster. With the use of existing system, the operator can not feel fatigue or to have applied more force at the time of lifting. The proposed invention proves to be a vital mechanism in lifting heavy equipment especially in engineering industries. The proposed invention can be easily adaptable and do not require heavy investments etc.
It will be apparent to those skilled in the art that various modifications and
variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

We Claim:
1. A hydraulic jack system for providing variable mechanical advantage to an operator during
operation comprising:
a jack assembly including a jack piston disposed within a cylinder, the jack piston openable outwardly from the jack cylinder to lift a load, the jack assembly connected to an oil reservoir through a manually operated control valve;
a pump connected to the oil reservoir through a withdrawing conduit for receiving oil when the pump exerts a suction stroke, the pump connected to the jack cylinder through a dispensing conduit for dispensing the received oil within the jack cylinder when the pump exerts a compression stroke;
a lever pivotally engaged within a slot of a support structure and positioned at an end of the slot formed within the support structure, the lever angularly displaceable along a vertical plane to allow the pump to exert the suction and compression stroke, pivotable end of the lever capable of being slidably movable to an opposite end of the slot; and
an additional piston-cylinder arrangement securely held within a jack frame and connected between the jack cylinder and the pump through corresponding conduits, free end of the piston having a flange member fixedly connected to the pivotable end of the lever, wherein when the piston expands the pivotable end of the lever slides to the opposite end of the slot.
2. The hydraulic jack system according to claim 1, wherein when load on the jack piston increases, a portion of the oil present within the jack cylinder is dispensed within the cylinder of the additional piston-cylinder arrangement thereby allowing the piston of the additional piston-cylinder arrangement to be expanded.

3. The hydraulic jack system according to claim 1, wherein the support structure is positioned in between the pump and the additional piston-cylinder arrangement, the slot formed adjacent to top surfaces of the support structure.
4. The hydraulic jack system according to claim 1, wherein an intermediate conduit is connected with the jack cylinder and extends to be connected with the cylinder of the additional piston-cylinder arrangement.
5. The hydraulic jack system according to claim 1, wherein the lever is shifting of the pivotable end of the lever on the opposite end of the slot allows changing the effective length between the pump and the pivotable end thereby increasing the mechanical advantage offered to the operator.
6. The hydraulic jack system according to claim I, wherein the pump includes a piston reciprocatably disposed within a cylinder, and wherein a biasing member is positioned between the piston and a bottom portion of the cylinder.