US 3806091 A
A hydraulic jack wherein the ram is moved in the ram cylinder by a selection of two or more pump pistons of different cross-sectional area whereby higher or lower pressures with consequent slower or faster movement of the ram can be selected at will, as the operating handle of the pump piston is actuated.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Wride [111 3,806,091 Apr. 23, 1974 HYDRAULIC JACKS  Inventor: Donald C. Wride, 35 Helen Ter.,
Valley View, Australia 5093  Filed: Aug. 8, 1972  Appl. No.: 278,766
30 Foreign Application Priority Data Aug. 12, 1971 Australia 5872/71  US. Cl 254/93 R, 60/482, 60/479  Int. Cl 1366f 3/24  Field of Search 254/93 R, 93 A, 93 M;
[5 6] References Cited UNITED STATES PATENTS 7 2,824,424 2/1958 Sebenick 254/93 R 2,434,296 l/1948 Swanson 417/487 Bivans 417/487 2,466,815 4/1949 Lightburn 60/482 2,535,759 12/1950 Schwantner 254/93 M FOREIGN PATENTS OR APPLICATIONS 591,358 4/1925 France 60/482 Primary Examiner0thell M/Simpson Assistant Examiner-Robert C. Watson Attorney, Agent, or Firm-Oldham & Oldham [5 7] ABSTRACT A hydraulic jack wherein the ram is moved in the ram cylinder by a selection of two or more pump pistons of different cross-sectional area whereby higher or lower pressures with consequent slower or faster movement of the ram can be selected at will, as the operating handle of the. pump piston is actuated.
8 Claims, 4 Drawing Figures PATENTEB m 2 3 i974 sum 3 [1F 3 1 HYDRAULIC JACKS BACKGROUND OF INVENTION This invention relates to improvements in and to bydraulic jacks.
It is customary in hydraulic jacks to utilize a pump of relatively small cross-sectional area which is actuated by means of a hand lever to force hydraulic fluid beneath a ram, which lifts the vehicle or the like for which purpose the jack has been designed, and to' provide with such a device a mechanism which can be operated, such as by twisting a handle or release, whereby the ram can be lowered after repairs to the vehicle or the like have been completed.
Jacks of this nature are relatively slow acting because of the need to utilize a number of pumping strokes to achieve the necessary raising while maintaining the pressures such that a heavy vehicle or the like can be lifted without the exertion of too great a force. It is this factor which makes the jacking relatively slow.
SUMMARY OF INVENTION The object of the present invention is to provide an improved form of jack in which light loads can be quickly raised but nevertheless to allow the greater pressures to be generated for lifting heavy loads.
It is a further object of the invention to provide a simple and effective release for a jack which can be actuated without the necessity of difficult manoeuvres such as reaching beneath the vehicle or the like to manipulate mechanism to allow the jack to be lowered.
A further object is to allow operation of the jack from various angles. I
The objects of the present invention are achieved by utilizing multiple pistons so arranged that depending on the stroke of the actuating lever the required rate of movement can be achieved while release of the device is preferably simplified by so arranging the release mechanism that an inward movement on the lever will release the fluid to lower the jack.
It will be realised that the invention can be constructed in various ways but to enable its nature to be fully appreciated an embodiment will now be described but it is to be clear that the invention need not necessarily be limited to this.
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view of a jack according to the invention,
FIG. 2 is a transverse section of same,
FIG. 3 is a view of a modified pump, and
FIG. 4 is a section on line 44 of FIG. 2.
The base 1 of the jack has on it a housing 2 which forms the container for the hydraulic fluid and within the housing is mounted the hydraulic ram cylinder 3 and the ram 4 by means of which lifting is effected. The usual screwed adjuster 5 is used to take up slack before commencing to lift.
The means for generating the pressure comprise a relatively small diameter piston 6 which can be reciprocated in the hollow of a larger diameter piston 7 by being connected to a handle coupling member 8, which has on it a fulcrum member 9 engageable in slots 10 in the housing 2. A pin 11 on the piston 6 engages a slot 12 in the handle coupling member 8 to allow the fulcrum member 9 to be engaged in any one of the arcuate slots 10 on the housing 2.
The smaller diameter piston 6, which is the high pressure piston, is coaxially arranged in relation to the larger diameter, or low pressure piston 7 and the piston 6 is so disposed therein that by extended movement of the handle 14 which is inserted in the socket of the coupling member 8 when the device is to be actuated, the smaller diameter piston 6 can move in the larger diameter piston 7 which is normally loaded by a spring 15 into a raised position.
The larger diameter piston 7 is disposed in a cylinder 16 which communicates on the one hand through a one way valve 17 and duct 18 with the housing 2 in which the fluid is held, and on the other hand through a one way valve 19 and duct 20 with the ram cylinder 3 of the hydraulic ram 4.
The larger diameter piston 7 is hollow and has an aperture 22 so that while its hollow communicates with the smaller diameter piston 6, the two pistons are so arranged that when the handle 14 is operated to bring the smaller diameter piston 6 into contact with the larger diameter piston 7 it closes off the aperture 22 in the larger diameter piston 7 and moves the larger diameter piston downwardly against the pressure of the spring 15 to displace -a relative large quantity of the hydraulic fluid into the pressure chamber 3 and thus gives rapid lifting of the ram 4 within this chamber.
Thus according to the device outlined, if the handle 14 is operated during say the lower half of its stroke it will directly operate the larger diameter piston 7 through the smaller diameter piston 6 and will give a quick action, but correspondingly lower lifting power, but immediately the ram 4 has reached a position where greater force is required to move it, the larger diameter piston 7 is allowed to return to its upper position against the stop 24 under action of the spring 15 and by appropriately then operating the handle 14 at a higher part of its stroke, the smaller diameter piston 6 only will be reciprocated, drawing the fluid from the housing 2 into the space below the larger diameter piston 7 but through the hollow of the piston and the aperture 22 into the hollow in the upper part of the larger diameter piston which then acts as the cylinder for the smaller diameter piston. By then pumping the smaller diameter piston it will be realised .that because of the lower area a much more powerful lift is obtainable.
Both pistons will of course be provided with the usual seals such as O-rings 25.
The ram cylinder 3 is associated with a release valve 27 which preferably operates as .follows.
Disposed adjacent to the hollow of the handle coupling member 8 in which the handle 14 is engaged is a button 28 which is in line with the handle 14 and is outwardly loaded by a spring 29. The button 28 forms part of a tapered release member 30 engaged in a socket 31 in the housing 2. A rod 32 is moved down when the button 28 is depressed and pushes the release valve 27 to 30 is held in the position where the ball valve 27 is closed under normal conditions but when the handle 14, by means of which the device is actuated, is pushed further into the handle socket, it contacts the button 28 and forces this release member back to operate the lever to release the release valve and allow the ram to retract. The handle 14 can simply be pushed axially, or can have a thread 35 so that by turning the handle it moves axially by having the thread engage a screw 36 which can however be withdrawn out of engagement with the thread to allow axial movement of the handle 14 without rotation.
Normally, the end of the handle 14 is clear of the button 28 and has no contact with the release member, but
when it is desired to lower the hydraulic jack it is only necessary to push the handle 14 further into the socket of the coupling member 8 whereupon its end will contact the button 28 and will force it back into a position where, through the connection to the release valve 27, the valve will be actuated.
While in the foregoing the two pistons 6 and 7 have been described as coaxially arranged it will be obvious that they can be otherwise arranged, and for instance three pistons could be used as shown in FIG. 3 where the piston 40 is the smallest diameter piston and an intermediate piston 41 is positioned in an expanded bore" while-a larger piston 42 is disposed in a still larger part of the bore.
In this case the bore 43 has a step 44 and a step 45, a strong spring 46 normally holding the piston 42 against the step 45 while a weaker spring 47 holds the piston 41 against the shoulder 44.
The pistons 4l and 42 have axial ducts through them, but the piston 40 has an end 50 which seals the duct 51 when the piston'40 is forced down, and in turn the duct 52 of the piston 42 is engaged by a seat 53 on the piston 41 to seal the piston 41 to the piston 42 when the piston 41 is forced down on to the piston 42.
To operate the device shown in FIG. 3, if high pressure is to be generated in the mastercylinder 3 to actuate the lifting ram 4, the smaller piston 40is reciprocated in a position where the end 50 does not close the opening 51 through the'piston 41 and the reciprocation of the piston 40 then draws oil from the housing and pumps it into the master cylinder, the oil flowing through the duct 51 and the duct 52 in the other two pistons without having any effect on the pistons.
Asthe piston 40 is the smallest diameter piston, it generates a relatively high pressure and is therefore used to exert the greatest force on the ram 4.
If a faster movement at a medium pressure is required the piston 40 is brought down until the end 50 seals the duct 51 within the piston 41 and the piston 40 is actuated in a somewhat lower position so that now the piston 40 does not leave the piston 41 but operates in the medium sized bore which is the position between the shoulder 44 and 45.
If a still quicker movement is required, the piston 40 is pushed down further until the end 53 of the piston 41 engages and seals on the piston 42, and now if the piston 40 is actuated downwardly from this position, all three pistons. will move as a unit, but the spaces be tween the pistons will b'eisolated because the piston 42 has its duct 52 now sealed to the duct 51 by the projection 53 on the piston 41 while the duct 51 in the piston 41 is sealed by the end 50 of the piston 40, so that now pumping takes place by movement of the piston 42 between the upper limit which is the shoulder 45 and the bottom of the bore of the largest part of the cylinder.
As stated, the spring 47 is lighter than the spring 46, so that during operation of the intermediate piston 41 the piston 42 will beheld against the shoulder 45 but when further pressure is exerted to overcome the pressure of the spring 47, the piston 41 seals to the piston 42 and actuation is then against the pressure of the spring 46.
To allow the jack to operate in any position, that is upright or lying down, the duct 18 in the base 1 has on it a nipple 60 to which is attached a flexible tube 61 the free end of which has on it a weight in the form of a ball 62, the ball having through it an opening 63 with which the tube 61 communicates so that when the jack is in To allow the operating handle 14 to be actuated from.
any one of a number of positions, the fulcrum member 9 can engage any one of the arcuate slots 10, this being achieved by pulling back the handle socket'8 on the pin 11, which is permitted because of the slot 12 in the handle socket 8, and engaging the fulcrum member 9 of the Coupling member 8 in one of the other arcuate slots 10 which will then allow the handle to be operated in a different position, the arrangement preferably being such that the handle 14 can operate from a substantially horizontal position when the jack is in a vertical placement, and can be used to pump downwardly from this position, to where the handle 14 can be inclined upwardly at its free end by engaging the fulcrum member 9 in a lower arcuate slot 10 and can be positioned at a considerable angle if the lowest arcuateslot 10 is engaged.
It will be noted from the drawings that the arcuate slots 10 are radiussed about the piston 6 of the pump,
that is referring to the embodiment shown in FIG. 2, so
arc 'of almost degrees before the fulcrum member.
9 leaves the arcuate slot 10, any of these positions being workable in that the-fulcrum member 9 will remain in engagement with its particular slot 10 even when turned throughthis relatively substantial arc, this allowing the jack to be operated from a number of positions and allowing the actuating handle 14 to be conveniently positioned for any particular operation.
While the button28 on the release member can be actuated by moving the handle 14 inwards against it, even when the handle is at an inclination to the axis of the button, it is preferred to operate it by moving the handle into substantial axial alignment with the member 30 of the release mechanism so the handle can push the button 28 inwards in a direct manner to release the valve 27 when the ram is to be lowered.
While in FIG. 3 a three stage pump is shown in which the pistons are inter-engagable to operate singly, that is the piston 40 only can be operated, or two pistons can act as a pair by bringing down the piston 40 on to the piston 41, or as a triple assembly by bringing down the piston 41 onto the piston 42, it will be realised that a two-stage or four-stage arrangement on this basis could equally well be achieved.
The difference of course between the arrangement shown in FIG. 3 and that shown in FIG. 2 is that in FIG. 2 the smaller diameter piston 6 operates within the larger diameter piston 7 and the piston 7 operates in a bore in a cylinder 16, while in the arrangement shown in FIG. 3, a stepped bore is used so that it can contain three different sized pistons each working in a specific part of the main bore.
1. A hydraulic jack comprising a base, a housing on said base to form a hydraulic fluid storage, a ram cylinder in said housing, a lifting ram axially movable in said cylinder and projecting from said cylinder and housing, a pump cylinder on said base, a duct with a non-return valve connecting said housing with said pump cylinder to allow flow of hydraulic fluid from said housing to said cylinder, a duct with a non-return valve connecting said pump cylinder with said ram cylinder to allow flow of hydraulic fluid from said pump cylinder to said ram cylinder, a manually operated return valve to allow hydraulic fluid to return from said ram cylinder to said housing, characterized by pistons of different diameters within said pump cylinder selectively operable by an actuating lever engaging a coupling member connected between said pistons and said housing, whereby a larger diameter piston can be actuated for quicker relatively lower pressure lifting of the said ram, or a smaller diameter piston can be actuated for slower relatively higher pressure lifting of the said ram, and wherein the said actuating lever can move axially in said coupling member, said coupling member being connected to said smaller diameter piston, and having a fulcrum member engaging one of a series of spaced slots disposed on said housing to allow the said fulcrum member to selectively engage any one slot to vary the relative operating position of the said lever.
2. A hydraulic jack according to claim 1 wherein the smaller diameter piston operates in a bore of the larger diameter piston which in turn operates in said pump cylinder, a spring to urge said larger diameter piston against a stop in a retracted position in said cylinder, the coupling member between said smaller diameter piston and said actuating lever allowing the said smaller diameter piston to be reciprocated in the bore of the said larger diameter piston to act as a relatively high pressure pump, said bore opening into said pump cylinder, and stop means between said larger diameter piston and said smaller diameter piston whereby when the stroke of said lever is increased the said smaller diameter piston carries the said larger diameter piston with it to cause the combined piston area to act as a relatively greater output pump for more rapid ram advancement.
3. A hydraulic jack according to claim 1 wherein the smaller diameter piston operates in a bore in the said pump cylinder and is connected by a coupling connection to said actuating lever and said large diameter piston operates in a bore in the said pump cylinder adjacent to the bore of the smaller diameter piston, an axial aperture through said larger diameter piston, a closure member on said smaller diameter piston to close said aperture when said smaller piston is moved to contact said larger diameter piston, and a spring to urge the larger diameter piston into that end of the larger diameter bore which is adjacent the smaller diameter piston, whereby as the smaller diameter piston is reciprocated in its bore a relatively high pressure pumping action results through the axial aperture of the larger diameter piston into the bore of the pump cylinder, but when the stroke of the smaller diameter piston is extended the smaller diameter piston engages the larger diameter piston and seals the axial aperture through the larger diameter piston whereby the larger diameter piston is then moved by the smaller diameter piston against the pressure of the said spring to act as a relatively greater output pump for more rapid ram advancement.
4. A hydraulic pump according to claim 3 characterized by at least one intermediate piston between said smaller diameter piston and said larger diameter piston disposed in a bore of intermediate diameter, said intermediate piston having an axial aperture through it with a seating to engage the axial aperture of the said larger diameter piston, a spring to urge the intermediate piston to that end of the intermediate bore which is adjacent the bore of the smaller diameter piston, said last defined spring exerting a lesser force than the said spring which urges the larger diameter piston to the end of its bore, whereby when the smaller diameter piston movement is extended to engage the intermediate piston and reciprocate it, the aperture of the intermediate piston is closed and the intermediate piston displaces hydraulic fluid through the aperture through the larger diameter piston to act as an intermediate output pump for an intermediate rate of advancement of the said ram, but when the smaller diameter piston and the intermediate piston are further extended in their reciprocation the intermediate piston engages the larger diameter piston to make the aperture of the larger diameter piston coextensive with the aperture of the intermediate piston to cause the larger diameter piston to act as a relatively greater output pump for more rapid ram advancement.
5. A hydraulic jack according to claim 1 wherein said hydraulic fluid return valve is actuated from an axially movable button on said housing in line with the said operating lever when engaged in said coupling member, whereby when said lever is moved to contact and depress said button, the said return valve is actuated to allow return of the hydraulic fluid from the ram cylinder to the housing.
6. A hydraulic jack according to claim 5 wherein the said lever has the end which engages the socket of the said coupling memberscrew threaded, and the coupling member has a member projecting into said socket to engage said screw thread, whereby when the said lever is rotated it moves axially through the said socket to engage and depress the said button.
7. A hydraulic jack according to claim 1 wherein the coupling member has a slot engaging a pin on the smaller piston, the slots in the housing being arcuate about the axis of the piston to allow orientation of the said lever about said piston axis.
8. A hydraulic jack according to claim 1 wherein the said duct which connects the housing with the pump cylinder opens into said housing through a flexible tube disposed in said housing and having a weight on its free end which is the intake end of the tube, whereby the intake end of the tube and hydraulic fluid in said housing are both positioned in the housing under the influence of gravity to allow hydraulic fluid to be drawn into said pump cylinder irrespective of the orientation of the said jack.