US2402572A - Hydraulic jack - Google Patents

Description

June 25, 1946. H. E. PAGE HYDRAULIC JACK Filed July 5, 1944 INVENToR. Eri @Fac/B Izq fifi/.

Patented June 25, 1946 HYDRAULIC JACK Herbert E. Page, Alhambra, Calif.

Application July 5, 1944, Serial No. 543,547

(ci. zal- 10) 2 Claims. 1

My present invention has to do with hydraulic Jacks and has as an object the provision of an improved hydraulic jack of simple and economical construction which is capable of application of pressure to the lifting piston at one pressure-volume ratio to relatively quickly move the workengaging arm into initial contact with the work to be lifted and at a different pressure-volume ratio for lifting the load.. I am aware that, in the prior art, there are hydraulic jacks which operate by virtue of such diierent pressure-volume ratios for initial contact and subsequent load lift, but my present improvements provide a vastly more simple and economical structure for accomplishing the purpose for which prior art jacks have required a more expensive and complicated structure.

The remaining objects are subordinate to the above-mentioned objects and will become apparent from the following explanation of a preferably preferred example of my invention, for which purpose I shall refer to the accompanying drawing, in which:

Fig. 1 is a longitudinal section; and

Fig. 2 is an enlarged fragmentary plan section taken on line 2--2 of Fig. 1.

In the drawing I show a body 5 which may be formed of a single casting providing a Workv cylinder 6, a pump cylinder l, and a iluid reservoir R. Y

Pivotally secured to the body by cross pin IIl there is a conventional lifting arm II pivotally and the inner end of the piston forms with th inner vend portion of the cylinder a main pressure chamber 35.

A connecting rod 38 has a spherical inner end 38a which nts in a corresponding socket in the inner end wall of the hollow piston and is piv-l otally connected at its outer end to the lower end of the lifting arm II by a pivot pin 39.

carrying a conventional work-contacting saddle I2. The arm II is adapted to be swung between the full and dash line positions shown in Fig. 1 and has an arcuate guide slot I5 through which a cross pin I4, secured at its ends in the body, projects. To maintain the saddle horizontal by rotating it about itspivotal connection I8 to the lifting arm, as the latter is moved, I provide a bar Il which is pivotally `connected at one enl by cross pin I8 to the saddle and pivotally con'- nected at its opposite end to the pin I4.

Rollers 20 are carried by any aXle 2| mounted .at its ends in the side extensions 22 of the body, and, in the conventional manner, rollers 25 mounted on an axle, not shown, are disposed at the underside of the opposite end of'the body,` so that the jack maybe rolled `from one location to'another.

Cylinder 6 has a reduced diameter inner end portion 5a and. a piston 30, having areduced diamdierent diameter portions of the cylinder md piston providing a pressure chamber annu larly of the piston sealed by seal rings 51, 31a,

' the pinion being mounted on a spindle 50 extending transversely of the recess 5I provided in the inner end of the body,V said spindle being journaled at its ends in the side walls of the recess.

A valve bore 55 is provided in the body and has different diameter portions providing three valve chambers 56, 51, 58 and valve seats against which seats ball check valves 59, B0, 5|, respectively, are adapted to seat. A floating valve-actuating member isdisposed between balls 59 and 80, said member carrying around its end portion a compression spring 65 bearing at its respective ends against ball 59 and the annular shoulder provided by the enlarged portion of member 55. A floating valve-actuating member 'l0 is disposed between balls 60, 8|, there being a compression spring 1I interposed between the shoulder provided by the enlarged portion of member 10 and the ball 50.

Ball 6I is urged seated by a relatively strong compression'spring l5 which bears at its other end in a recess provided in the inner end of a threaded plug'I'B.

A port 88 provides communication between the reservoir R and bore 55 at the right of ball 55; a port 8l provides communication between the pressure chamber 82 provided by the piston 45 in cylinderl, and the bore 55- at a point between the balls 59 and 60; a port 84 provides communication between the chamber 35 and the bore 55 at a point between balls 60 and4 5I; and a port 85 (Fig, 1) provides communication between chamber 38 and bore 55 at vthe left of ball 6I.

The significance of the ports and valve members described will be understood from the fol lowing description oi operation.

As the lever 49 is oscillated to operate pinion 48 and rack 48, piston 45 is reciprocated in cylinder 1. On each suction stroke of that piston, lluid `will be drawn into chamber 82 from the 3 reservoir through port 80, .bore 56 and port 8| past ball valve 59 and, until the arm II is raised sufliciently to initially contact the saddle I2 with the Work to be lifted, on each pressure stroke of piston 45 the fluid thus drawn into chamber 82 by each suction-r stroke of said piston will be forced into chamber 35 through port 6I, bore 55 and port 84 past ball valve 6II. Spring 15, being relatively strong, will maintain ball 6I seated until the saddle I2 meets sufllcient resistance to further upward movement to cause the ball 6I to unseat against the pressure of the spring 15. Thus the initial pressure is all communicated to the relatively small chamber 35 to quickly move the arm I I until the saddle initially contacts the work, after which each pressure stroke of the pumping piston will force fluid past both valves 60, 6I into both chambers 35, 36 to lift the load after the initial contact has been thus established.

During the initial movementy of piston 30 to .establish contact of the work-engaging saddle with the work to be lifted, make-up fluid lwill be drawn into chamber 36 from the reservoir through ports 90 and 9| in plug 16 and port 85, past a ball valve 92 which latter is urged` seated by a spring 93. Ports 90 extend radially through the reduced diameter portion of plug 16 to communicate with the annular chamber 90a, which latter in turn communicates with the reservoir through port 94.

To lower the jack, the fluid pressure in chambers 35, 36 may be released by screwing inwardly on the valve-actuating screw 95, whose stem 96 engages ball 5 9 to push the latter oil its seat and that in turn'unseats balls 60, 6I through the medium of the actuating members 65, 1II. An operatinglink 91 is pivotally connected to the member 95. ,When the member 95 is rotated in the opposite direction, its stem 96 disengages the ball 59 and the-Springs 66, II and 15 return the ball valves to their` seats.

The spring 40 positively returns the piston 30 to its inner position shown in the drawing after the arm I I ceases to be swung downwardly by the load.

By virtue of the gradually increasing diameters of the valve ' chambers 56, 51 and 58 and ball valves 59, 6U and 6I, the valvey elements may be readily assembled in bore 55 by dropping them into the outer or left-hand end of bore 55 before applying the plug 16, since the balls will, by virtue of their different sizes, automatically nd their appropriate seats. 'Ilhis structure simplifies assembly and repair.

While, in the foregoing, I have resorted to considerable detail of structure and association of parts in describing a particular example of my invention, I Wish it to be understood that I have done so merely to make my invention understood and that I do not limit my invention to such details. On the contrary, my invention is only to be limited as appears in the appended claims.

I claim:

l. A hydraulic jack comprising a body providing a fluid reservoir and bores providing a work cylinder and a' pumping cylinder, a lifting arm pivotally mounted on the body to swing relative thereto into and out. of Work-engaging position, said work cylinder having an inner portion of relatively reduced diameter, a work piston reciprocally mountedin the work cylinder, said piston having a relatively large diameter'outer end portion and a reduced diameter inner end portion .providing an inwardly facing annular shoulder, seal ring means cooperating with the work cylinder and work piston to provide an auxiliary pressure chamber annularly of the smaller diameter portion of the work piston to which chamber said shoulder is exposed, the inner end of the work piston forming with the inner end portion of the work cylinder a main pressure chamber, a connecting rod whose opposite ends engage the work cylinder and arm, a pumping piston reciprocally mounted in the pumping cylinder and providing therewith a pressure-generating chamber, a valve bore in the body, said valve bore providing a valve seat at its inner end, a valve seat at its outer end, and an intermediate valve seat, inner, outer and intermediate checky valve means cooperating with said respective seats.; Spring means yieldably urging each of the check? valves seated towards the pressure-generating? chamber, the spring means urging the outer check' valve seated being relatively'stronger than the spring means urging the other check valve'means seated, a port providing communication between the reservoir and the inner end of the valve bore, a port providing communication between the pressure-generating chamber and the valve bore at a point between the inner and intermediate Acheck valves, a port providing communication between the outer end of the valve bore and the main pressure chamber, a port providing communication between the auxiliary pressure chamber and the valve bore at a point between the outer and intermediate check valves, a makeup fluid port providing communication between the reservoir and the main pressure chamber, a` check valve controlling the latter port and seating towards the reservoir, and means for actuating the pumping pisto 2. In a hydraulic jack having a body presenting a fluid reservoir, an auxiliary, fluid pressure chamber and a main iiuid pressure lchamber, a work-engaging arm pivotally mounted on the body to swing relative thereto, arm-actuating means having portions exposed to and movable in response to pressure in said chambers, and pressure-generating means, means controlling communication of :uid from the pressuregenerating means to said chambers including aI bore extending through the body, said bore providing an inner valve chamber, an outer valve' chamber of largerdiameter than the inner valve chamber and an intermediate valve chamber of a diameter intermediate the diameters of the other valve chambers, each of lsaid valve cham- Ybers providing a. valve seat, ball valvemeans of different diameters cooperating with said respective seats to control the inlets to the respective chambers, ball valve-engaging members float-l ingly disposed in the bore between the ball valve means, a plug closing the outer end of the bore, a plug threadedly mounted in the other end of the bore and having a portion engageable against the innermost ball valve means in response to rotation of the last-mentioned plug relative to the body, means providing fluid communication from the reservoir to the inner valve chamber, saidmeans being controlled by the ball valve in the inner valve chamber, a body port providing cation between `the outer valve chamber and the main pressure chamber. HERBERT lil.- PAGE.

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