US2439183A - Hydraulic jack - Google Patents

Description

H. E. PAGE HYDRAULIC JACK April 6, I1948.

Filed March 20, 1944 Patented Apr. 6, 1948 HYDRAULIC JACK Herbert E. Page, Pasadena, Calif.n

Application March 20, 1944, Serial N0."527,199

Claims'.

'Ihis invention relates to hydraulic pressuregenerating apparatus. While not so limited in its use, it is particularly well adapted-for use as a hydraulic jack and is in the nature of an im provement upon the apparatus more particularly shown and described in my copending application Serial No. 511,424, i'lled November 23, 1943, of

which application this is a continuation-impart.

In my said copending application I show a hydraulic jack wherein the work-lifting piston is initially automatically moved into work-contacting position by means of a spring interposed between the lifting piston and the jack body, after which contact the hydraulic pressure for lifting the load is generated by a pumping piston. In

that adaptation, however, in lowering, after the llifting piston is freed of the load, it is necessary to operate the pumping piston to hydraulically compress the spring which functions as before described to initially move the lifting piston into contact with the work.

By my present invention I overcome the neces- Fig. 1 is a longitudinal medial section of a lack embodying my invention;

Fig. 2 is an enlarged section taken online 2--2 of Fig. 1:

Fig. 3 is a reduced section taken on line 3-3 of Fig. 1;

Fig. 4 is a reduced section taken on line I--I of Fig. 1: and

Figs. 5, 6 and 7 are enlarged cross-sectional views of the control valve element taken on line .'rof Fig. 2, showing the valve in different posi# tions.

Referring to the drawings, I show a body 5 having a recess 6 in its front or right-hand end sity of pumping the lifting pistoninto the frully retracted position after it is freed ofthe load and itis among the principal objects to provide a hydraulic Jack in which the movement of the lifting piston into work-contacting position is accomplished automatically by spring or mechanical means. as described in my said copending application, and also in which the return of the lifting piston to its initial retracted position is accomplished by automatic means.

In general, I accomplish the above-named pur pose by providing, in a combination with .the means for operating the work-lifting piston in its work-contacting and lifting operations, a surge chamber in which pressure for returning the work-lifting piston to its starting position is generated while th-e work-lifting piston is performing its lifting operation.

My present invention has still further advantages which will become apparent from the following detailed description of a presently preferred adaptation which I have chosen for explanatory purposes. I wish it understood, however, that I do not intend to confine my invention, in its broader aspects, to the particular details of construction and association oi parts now to be described because, within the scope of the appended claims, it is susceptible of .being carried out in otherrand modified physical forms which the ensuing description will suggest to those skilled in this art.

For purposes of the following description I shall i refer to the accompanying drawings, in which:

and a recess I in its rear or left-hand end. A conventional lifting arm 8 is pivoted at 8a between the side walls of recess 1 and a segmental pinion 9 is mounted on a transverse spindle 9a extending between the side walls of recess 6. A handle H is secured tothe pinion, by which handle the pinion is manually operated. The body presents a hydraulic fluid reservoir R.

A work cylinder I5 is provided in the body, within which a work-lifting piston I6 re'ciprocates. Piston I6 consists of an outer tubular member I'6a and an inner cylindrical member Iiib held in the outer member by a snap ring 2i. The outer end of the cylinder has secured therein, as by snap ring I9, a sleeve I1 carrying seal rings I8, I8a. Piston member I6b is provided with an inwardly facing shoulder 2li against which one end of a coil spring 22 bears, the opposite end of the spring bearing against the inner end of the cylinder I5 to normally urge the piston outwardly into such position that arm 8 is swung into initial contact with the work to be lifted. In the position shown in the drawing, spring 22 is compressed by hydraulic fluid pressure in an annular chamber 25 provided between the reduced diameter portion of the piston member IBa and the cylinder wall. The manner in which pressure is communicated to and released from chamber 25 will be later described.

Piston member I6b is longitudinally bored to receive a connecting rod 26, the inner end wall pro- A cylindrical 3|` in the body has reciprocally mounted therein a piston or plunger 32 whose inner end provides with the inner end portion oi.' the cylinder a surge chamber 33, into which chamber the piston is urged by a coil spring 34 acting between the piston and the outer end of the cylinder. The spring is shown in partly compressed position. The outer end of cylinder 3| is vented to atmosphere through a port 3Ia and its inner end is closed by a threaded plug 3 Ib.

A pressure-generating cylinder 35 is provided in the inner end of the body, in which a pumping piston 36 reciprocates, the latter piston terminating at its outer end portion in a rack 36a which is engaged by the pinion 8 to reciprocate the piston. Thus, a pressure-generating chamber 38 is provided between the inner end of cylinder 35 and the inner end portion of piston 36. Chamber 38 communicates with the reservoir R through a port 31, which port is controlled by a spring-pressed ball check valve 39 seating towards the reservoir, so that on the suction stroke of piston 36 lluid is drawn into chamber 38 from the reservoir.

A tapered valve bore 48 is diagonally disposed in the body and has rotatably mounted therein a valve 42 having a stem 42a of squared cross-section fitting into a similarly shaped recess in an actuating member 43. Member 43 is bifurcated at its outer end and between the bifurcations an operating rod 44 is pivotally connected by pin 44a. A spring 45 interposed between the valve 42 and member 43 around stem 42a urges the tapered valve 42 into the tapered portion of bore 48, which spring pressure is augmented by hydraulic pressure communicated through a port 59 as will be hereinafter described.

Valve 42 has radial. ports 58, 5I, 52, 53 which communicate with each other at their inner ends, and a port 55 which communicates at its inner end with a longitudinal port 56 in the valve, which latter port communicates at its other en d with the reservoir R through the inner end of bore 48 and a body port 51.

Chamber 38 communicates with the valve bore 48 through ports 58 and 58 controlled by a springpressed ball check valve 54 seating towards chamber 38, the spring urging the valve 54 seated bearing at its other end against a plug 54a threaded into a bore in the body. The pressure communicated through port 58 acts against the valve 42 in-addltion to the pressure of spring 45, during the pressure stroke of piston 36, to urge valve 42 into sealing relation with the tapered portion of the bore. l

Oppositely disposed, transverse bores 68, 6I are provided in the body, said bores having reduced openings 68a, 6Ia, respectively, communicating with bore 48 at the periphery of an eccentric cam 62 carried by the inner end of valve 42, which bore 48 in turn communicates with the reservoir through passageway 51.

A sleeve 64 is threaded into bore 68 to provide a seat for spring-pressed ball check valve 65, which seats towards bore 48, the outer end of bore 68 being closed by a threaded plug 66. Ball 65 is urged seated by a spring 68. A spring-pressed poppet 61 having stems 61a, 61b seats towards bore 48 in the reduced inner end of bore 68, the ball being urged seated by a spring 61o.

A sleeve 18 is threaded into bore 6| to provide a seat towards bore 48 for ball valve 1I, which valve is urged seated towards the bore 48 by a spring 12 bearing at its outer end against threaded plug 13. A spring-pressed poppet 15 having stems 15a. 15b seats towards the bore 48, being urged seated by a spring 15e. Stems 61a, 15a are alternately engageable by cam 62 upon rotation of valve 42 to cause those stems to engage and unseat the respective poppets 61, 15 and balls 65, 1|.

A body'port 88 communicates at one end with bore 48 and at its other end with bore 68 between ball 65 and poppet 61, and a port 8| communicates at one end with valve bore 48 and at its other end with bore 6I between valves 1I and 15. A body port 83 communicates .at one end with the bore 6I beyond the ball valve 1I and communicates at its other end with chamber 38.

A body port 84 communicates at one end with bore 6I between the valves 1I, 15 and communicates at its other end with the surge chamber 33, a spring-pressed ball check valve controlling the port and seating away from the surge chamber so that as piston 36 is reciprocated to generate pressure in chamber 38, pressure is simultaneously generated in the surge chamber 33 to move piston 32 to the left therein' against the action of spring 34. A body port 81 communicates at one end with bore 58 beyond the ball valve 65 and communicates at its other end with the chamber 25 for the purpose to be described.

A port 88 provides communication from the surge chamber 33 to the chamber 25 through port 88, valve 42, port 88, bore 68, and port 81; port 88 being controlled by a spring-pressed ball check ments described will become apparent from the following description of operation.

When the parts are in the relative position shown in the drawings, the valve 42 is in the position shown in Fig. 5, in which position the piston 36 may be freely reciprocated without aecting any of the pressure chambers-that is, the port 58 leading from the pressure-generating chamber 38 is in communication only with port 55 in valve 42 which communicates with the reservoir. Valve ports 58, 5l, 52 are out of communication with any body port and although valve port 53 -is in communication vwith surge chamber 33 through port 88, port 53 is not in communication with any outlet so that pressure cannot escape from the surge chamber.

To change the position of valve 42 for raising the load, that valve is rotated counterclockwise to the position of Fig. 6 ln which position the cam 62 engages valve stem 61a to unseat valves 61, 65, releasing pressure in chamber 25 to reservoir, thus allowing spring 22 to initially move piston I6 outwardly of the cylinder to establish contact of that piston with the work to be lifted. In this position valve port 52 is in communication with port 8| and valve port 50 is in communication with chamber 38 through port 58, so that reciprocation of piston 36 draws fluid from the reservoir through port 31 on each suction stroke, and on each pumping stroke forces fluid from chamber 38. through body port 58, valve ports 58, 52, body port 8|, past valve 1I, and through body port 83 into the chamber 38 to force piston I6 further outwardly. During the said initial movement of the piston I6 under the iniiuence of spring 22, makeup fluid will be drawn into chamber 38 from the reservoir past valves 15, 1I. Also, the reciprocation of piston 36 to generate pressure in chamber 38 as before described simultaneouslybuilds up pressure in chamber 33 through port 84, to force piston 32 to the left, compressing spring 34.

vTo lower the load, valve 42 is rotated clockwise from the position of Fig. 6 to that of Fig. 7, in

which latter position cam $2 engages valve stem 15a to unseat valves 15, 1|, allowing pressure to be released from chamber 30, the iluid therein returning to the reservoir, and allowing the piston I8 to move inwardly as far as it may bc,

under influence of the load being lowered, and placing valve ports 5|, 52, 53 in communication with the body ports 5I, 80, 88, respectively,

so that fluid under pressure may pass from chamber 33 under the influence of the springpressed piston I2, through ports 88, l52, 53, B0, bore 80, and port I1 into chamber 25 to further move piston i8 inwardly against the action oi spring 22.

If insufiicient iluid is left in surge chamber 33, the pump 3B may be moved to force fluid into chamber to compress spring 22 and so i dinally in the bore and bearing at its inner end` against said wa-ll, a main pressure chamber formed by the inner end portions of the pistons and the inner end portion of the main cylinder,

a compression spring interposed between the inner piston and the inner end of the cylinder,

said spring normally urging the pistons outwardly of the main cylinder, an annular pressure chamber formed by the periphery of. the tubular piston and the side wall of the cylinder, said tubular piston presenting an annular outwardly facing shoulder exposed to the annular pressure chamber, a surge chamber provided by the body, valve-controlled means providing com munication between the surge cham-ber and the annular chamber, a plunger reciprocally mounted in the surge chamber, a compression spring cooperating with the plunger whereby upon expension to move the plunger inwardly to force fluid under pressure from the surge chamber to the annular chamber, uid pressure-generating means and valve-controlled means providing communication from the fluid pressure-generating means to the main chamber to move the piston outwardly thereof and to the surge chamber to move the plunger. outwardly thereof against the action of the last-named spring.

2. Hydraulic apparatus comprising a body providing a main cylinder, a tubular piston reciprocally mounted in the main cylinder, an inner piston secured in the tubular piston and presenting a longitudinal bore opening through its outer end, a wall closing the inner end of said bore, arod disposed longitudinally in the bore and bearing at its inner end against said wall, a main pressure chamber formed by the inner end portion of the pistons and the inner end portion of the main cylinder. a compression spring interposed between the inner piston and the inner end of the cylinder, said spring normally urging the pistons outwardly of the main cylinder,` an annular pressure chamber formed by the periphery of the tubular piston and the side wall 'of the cylinder, said tubular piston presenting an annular outwardly facing shoulder exposed to the annular pressure chamber, a. surge chamber provided by the body, valvecontrolled means providing communication between the surge chamber and the annular chamber, a plunger reciprocally mounted in the surge chamber, a compression spring cooperating with the plunger whereby upon expansion to move the plunger inwardly to force fluid under pressure from the surge chamber to the annular chamber, iluid' pressure-generating means and valve-controlled means Vproviding communication from the iluid pressure-generating means to the main pressure chamber, the annular chamber and the surge chamber.

3. In hydraulic apparatus, the combination of a body providing a fluid reservoir, a ram cylinder, 'a pressure storage Vcylinder and a pump cylinder, a ram mounted to reciprocate in the ram cylinder and forming therewith opposed first 'and second pressure chambers, a springloaded plunger mounted to reciprocate in the pressure storage cylinder, a pumping piston mounted to reciprocate in the pump cylinder,

spring means in the first pressure chamber vand cooperable with the ram to move the latter outwardly of the ram cylinder to a limited extent,`

selectively cooperating with the conduits as to provide simultaneous communication oi' the pump cylinder with the rst pressure chamber and the pressure storage chamber and of the second pressure chamber with the reservoir and thence to close said communications andestablish communication of the storage chamber -with the second pressure chamber.

4. In hydraulic apparatus, the combination of a body providinga iluid reservoir, a ram cylinder, a pressure storage cylinder and a pump cylinder, a ram mounted to .reciprocate in the ram cylinder and forming therewith opposed rst and second pressure chambers, a pumping piston mounted to reciprocate in the pump cylinder, spring means arranged to move said ram relatively to said ram cylinder in the same direction said ram is urged by pressure in said rst pressure chamber, conduits connecting said rst and second pressure chambers to said reservoir, normally closed valves in said conduits, valve actuating means settable from a rst ineffective position to second and third positions successively to open the valves controlling communication of the second and first pressure chambers with the reservoir, conduits connecting said pump cylinder to said first and second pressure chamber, to said reservoir and to said pressure storage cylinder and another conduit connecting said storage cylinder to the said second pressure cham-ber of said ram cylinder, and passages within said valve actuating means variably communicating said conduits with one al1- other in such wise that said pump cylinder is connected in the rst position of said means with said reservoir and in the second and third positions thereof with said first and second pressure chambers, respectively, said actuating means further acting in its said second position to connect said pump cylinder to said pressure storage cylinder and in its said third position to connect said storage cylinder to the inder.

5. Hydraulic apparatus comprising a body. a ram cylinder in said body, a ram reciprocable in saidbody for protractive and retractive movements, a spring arranged to cause limited protractive movement of said ram, said body further comprising hydraulic pressure generating means, a reservoir of hydraulic uid and hydraulic pressure accumulating means, a plurality oi conduits interconnecting said cylinder, said pressure generating means, said reservoir and said accumulating means, and hydraulic control means settable to a plurality of positions selectively to interconnect said conduits, said control means acting in a first position to enforce idling of said pressure generating means, in a second position to permit protractive movement of said ram by said spring and by said pressure generating means and simultaneously a charging 'of said accumulating means, and acting in a third position to permit retractive movement of said ram by said pressure generating means and by said accumulating means.

HERBERT E. PAGE.

REFERENCES CITED The following references are of record in the le oi this patent:

UNITED STATES PATENTS Number Name Date 1,290,203 Houk Jan. 7, 1919 1,663,513 Howse Mar. 20, 1928 1,852,544 Weaver Apr. 5, 1932 2,096,574 Denny Oct. 19, 1937 2,099,368 Levy Nov. 16, 1937 2,200,392 Goldberg May 14, 1940 2,239,566 Mercier Apr. 22, 1941 2,283,516 Tyler May 19, 1942 l FOREIGN PATENTS Number Country Date 772,872 France 1934

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