US1964003A - Hydraulic jack - Google Patents

Description

J. P. MCBRIDE HYDRAULIC JACK June 26, 1934.

Filed Sept. 24. 1930 2 SheetsSheet 1 ATTORNEY June 26, 1934. J. P; MCBRIDE 1,964,003

HYDRAULIC JACK Filed Sept. 24, 1930 2 Sheets-She et 2 INVENTOR TTORNEY Patented June 26, 1934 1,964,003 HYDRAULIC JACK James P. McBride, New York, N. Y.,

Gerald S. Garrick, Mount Vernon,

assignmto N. Y. I

Application September 24, 1930, Serial No. 484,009

Claims.

My invention relates to hydraulic jacks and has particular reference to portable jacks.

Amongst the several objects of the invention 5 are to provide a hydraulic jack comprising a reservoir in which fluid is maintained under pressure at all times for the purpose of effecting initial projection of the ram of the jack; to provide means in such a jack for adjusting the pressure under which the fluid is maintained; to provide a novel arrangement of pump reservoir and cylinder in a hydraulic jack resulting in a compact and readily portable device; to provide in combination with a jack reservoir under pressure at all times simple and effective valve means for controlling flow of pressure fluid from the reservoir to the other elements of the jack, and to provide an improved form of hydraulic jack which is sturdy, reliable and cheap to manufacture. Other and more detailed objects of the invention will become apparent from a consideration of the following description of a preferred embodiment oi the invention, which is illustrated in the accompanying drawings forming a part of this specification,

1n the drawings: Fig. 1 is a central vertical section of a jack embodying the invention;

Fig. 2 is a top plan view of the jack shown in Fig. 1; I Fig. 3 is a section takenon Fig. i;

Figs. 4 and 5 are sections taken on the lines 4--4 and 5-5 respectively of Fig. 2; and

Fig. 6 is an elevation of the jack partly in section, as viewed from the side opposite Fig. 1. Referring now to the drawings,.10 represents the body of the jack, preferably an integral casting providing a ram cylinder 11 and a cylindrical reservoir 12 for the reception of pressure fluid. Between cylinder 11 and reservoir 12 there is located a pump cylinder 13 which in the present instance is shown as formed by a separate sleeve 14 screwed in a suitable recess in the body of the jack. The pump-cylinder may, however, be formed integrallywith the pump the line 3-3 of body and for the purpose of this specification is considered as a part of the latter. The lower part of reservoir 12 is connected to the lower part of the pump cylinder 13 by way of conduit 15, the .end of this conduit adjacent the pump -.cylinder being conical as at 16 to afford a seat for the pump suction valve 17. Valve 17 is provided with a short guide stem 18 and the seating surface of the valve is formed by a conical washer 19 of leather or similar substance, and the valve is loosely retained in position by a suitable stop which in the present instance is in the form of a plurality'of fingers 20 extending downwardly from the bottom of sleeve 14. When, as in the form illustrated, the pump cylinder comprises a separate sleeve, a suitable packing washer 21 is inserted between the sleeve and the pump body to prevent leakage.

As shown in Figs. 3 and 4, the bottom of the pump cylinder 13 is connected to the bottom of the ram cylinder 11 by way of passages 22 and 23, there being interposed between these passages the pump discharge valve 24. Valve 24 is of the same type as the suction valve 1'7, being provided 70 with a conical face 25 formed of leather or like material, and adapted to seat in a suitable conical part of passage 22. The pump discharge valve 24 is held against its seat by a spring 26 retained between the valve and a cap 2'7 screwed 75 into a suitable recess in the base of the body and seating against a packing washer 28.

A pump plunger 29 is'mounted in cylinder 13 and is preferably provided at its lower end with a leather packing cup 30 of the usual form. P1unger 29 ext'endsirom the pump cylinder through suitable packing 31 held in place by a" gland 32, and at its upper end is pivoted to a bifurcated operating lever 33, the arms of which are connected by means of pivoted links 34 and 35 to lugs 36 and 37 projecting from opposite sides of the ram cylinder. The free end of lever 33 is preterably provided with a radially extending pin or lug 38, and a hollow operating handle 39 f provided with a curved slot 40 is adapted to slide over the lever 33, the slot 40 engaging the .pin 38 to lock the handle in place.

A. second means of communication between the reservoir 12 and the ram chamber is provided by passages 41 (Fig. 5) and 42, the latter passage 95 communicating with passage 15 between the reservoir and the pump suction valve 1'1. Between passages 41 and 42 an annular seat 43 is formed lnthe pump body and a check or'relief valve 44 is-adapted to engage seat 43 to close communication between passages 41 and 42. Valve 44, as shown, is preferably in the form of a metal cup having therein an annular washer 45 of leather or the like adapted toven'gage seat 43. This valve is positioned so as sure of fluid tending to flow through conduit 41 to conduit '42 and is normallyrheld against its seat by a spring 46, situated between the valve and a retaining cap 47 screwed into the jack body andseatinc a ainst a packing washer 48. 110

to be closed by; the presextends upwardly from valve 44, this passage passage.

serving to receive a release pin 50, the lower end of which is of reduced diameter providing a clearance between the pin and the walls of the The upper portion of the pin projects from the jack body through suitable packing 51 retained by a gland 52. A cover plate 53, forming a closure for the upper end of the reservoir 12, is provided with an extension 54 carrying a pivot pin 55 on which is mounted a release lever 56 arranged to contact the upper end of the release pin 50. The free end" of lever 56 is preferably of the same diameter as the corresponding end of lever 33 ,and is provided with a radially extending pin 5'7 similar to ,pin 38, so that the operating lever 39 may be used interchangeably to actuate either lever 33 or lever 56.

A central cylindrical web 58, forming part of cover plate 53, serves as a guide for piston 59, the latter being located within reservoir 12 and having an upwardly extending annular flange 60 slidably engaging the web '58. Piston 59 has secured to its lower face a leather packing cup spring 26. When the jackis tion. Whenthe ram depression of the 61 of'the usual form.

A threaded hole 62 is provided through the upper end of web- 58 for the reception of an adjusting screw 63, and a coil spring 64 is situated between the piston 59 and a suitable spring retainer 65 bearing against the lower end of the adjusting screw 63. The projecting end of the adjusting screw 63.is preferably provided with a knurled head 66 or its equivalent for provide ing for manual adjustment of the screw.

Assuming the jack to be filled with fluid the operation is as follows: The fluid in the reservoir 12, which is maintained under pressure by means of piston 59 and spring 64, is prevented from flowing from the reservoir to the ram cylinder through passages 41 and 42 by the valve 44,

.which is held against its seat by spring 46, the

tension of this [spring being sufiicient to close the valve against the pressure maintained by spring 64in the reservoir. Pressure in the reservoir, however, is suflicient to force fluid to the suction side of the pump but not through the pump-discharge valve 24 which is seated by placed in position to effect lifting, valve 44 is opened manually by lever 56, i which acts through the valve 44 against the pressure of spring 46. This permits fluid to flow from the reservoir under the pressure created by spring 64 to initially project the ram against the work to be lifted. Lifting of the work is accomplished by manual operation of the pump to which fluid is always supplied under sufficient. pressure to prevent breaking of the pump sucis projected under load by operation of the pump, return flow of fluid from the ram cylinder to the reservoir-by way of conduits 41 and 42is prevented because of the fact that the valve 44 seats toward the reservoir, so that this valve is seated with greater force as the pressurein the ramcylinder increases.

When it is desired to permit theram to retract, the valve 44 is again manually openedand fluid is forced, by retraction of the ram, back to the reservoir against the pressure of spring- 64. Initial retraction of the ram will, of course, be effected by downward movement of the ob-' ject lifted by the ram, and when the object is lowered until there is no further load on the ram, the ram-will still be in contact with the object due tothe pressure exerted on the reservoir the pin 50 to open be cheaper in cost,since they do.

by spring 64. For this reason it is important tobe able to adjust the force exerted by spring 64 so that the fluid inthe reservoir is maintained under just sufficient pressure to overcome the frictional resistance to movement of the'ram. This adjustment is provided by the screw 63, which may be readily adjusted in accordance with the friction characteristics of each individual jack. not only as between different jacks, but also in the same jack under different conditions, and the adjusting feature permits the jackto be made self-raising without endangering easy retraction of the ram due to too great a pressure within the reservoir.

In order to facilitate withdrawal of the jack from beneath an object which has been lifted, the operating handle 39 is provided with a locking These characteristics will vary slot 40 so that the jack can be pulled from beneath tion set up by the pressure from reservoir '12.

After withdrawal of the jack final retraction of the ram may be readily accomplished upon actuation of the valve 44 to permit return flow of fluid from the cylinder to the reservoir. With the fluid in the reservoir constantly under pressure due tothe action of spring 64 it is necessary to provide exceptionally tight valves in order to prevent leakage from the reservoir to the ram cylinder either by way of the pump channels or passages 41 and 42. For this purpose, I have found valves of the type disclosed, provided with a non-metallic resilient facing such as leather or the like, and seating against the metallic walls of the channels to be superior to ametal valve, and furthermore to not require great accuracy in manufacture in order to provide a satisfactorily fluid-tight closure.

While in the embodiment shown I have illustrated a separate by-pass conduit comprising passages 41 and 42 controlled through a separate valve 44, the invention is not limited.to this particular type of construction, but may be carried out by an equivalent arrangement wherein the pump valves are positively opened vundermanual control to provide a free by-pass channel through the pump for permitting flow of pressure fluid from the reservoir to the ramcylinder for initialprojection thereof, and for permitting return flow of fluid from the ram cylinder to the reservoirupon retraction ofthe ram. v

From the foregoing description it will be obvious that various other changes and modifications in the device illustrated may be made with- ,out departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. A portable hydraulic jack comprising 2. A portable hydraulic jack comprising I integral body providing'an upright ram cylinder and a cylindrical reservoir for pressure fluid adjacent to said cylinder, a cover plate for said reservoir, a piston located in said reservoir and having a guide slidably engaging said cover plate, -an

adjusting screw mounted said cover plate and 159 a spring situated between said adjusting screw and said piston adapted to act on the piston to force fluid from the reservoir, a ram in said cylinder, a connectionfor flow of fluid from the reservoir to the cylinder, a valve in said connection for controlling said flow, a spring for seating said valve and manually operable means for opening the valve.

3'. A portable hydraulic jack comprising an in tegral body providng an upright ram cylinder, a cylindrical reservoir for pressure fluid adjacent to said cylinder and a pump cylinder situated between the ram cylinder and the reservoir, 13. cover plate for the reservoir, a piston in the reservoir, said piston having an extension guided in said cover plate, a spring disposed between the piston and the cover plate, said spring acting on the piston to force fluid from the reservoir, and con-- duits for flow of pressure fluid to the ram cylinder and to the pump cylinder, a check valve for preventing flow through the conduit from the reservoir to the ram cylinder and manually operable means tor opening said check valve,

4. A portable hydraulic jack comprising an integral body providing an upright ram cylinder, a cylindrical reservoir for pressure fluid adjacent to said cylinder and an upright pump cylinder situated between the ram cylinder and the reservoir, a cover plate for the reservoir, a. pistonin the reservoir, said piston having an extension guided in said cover plate, a spring disposed between the piston and the cover plate, said ring acting on said piston to force fluid from the res- I ervoir, an adjusting screw for varying the force exerted by said spring, said adjusting screw projecting through said cover plate and having a head providing for manual adjustment of the screw, a plunger in said pump cylinder, a lever pivotally mounted on the ram cylinder for actuating the pump plunger, said lever projecting from the cylindrical reservoir and having a free end adapted to receive a detachable operatin handle, conduits formed in said body for flow of pressure fluid from the reservoir to the ram cylinder and to the pump cylinder, a check valve for controlling flow through one of said conduits between the reservoir and the ram cylinder, said check valve opening away from said reservoir, a 'spring for closing said valve, said last named spring normally acting to'maintain the valve closed against fluid pressure created by said first mentioned spring, a valve operating rod mounted in said housing and projecting upwardly therefrom, said rod being adapted to open said check valve against the action of its closing spring, and a lever pivotally mounted on said body for actuating said valve operating rod, said last named lever having a free end adapted to receive a detachable operating handle.

5. A portabie hydraulic jack comprising a body providing a ram cylinder and a reservoir for, pressure fluid, a piston in said reservoir, 9, spring acting on said piston for creating and maintaining pressure at all times on fluid in said reservoir, a manually operable pump, conduit means connecting said reservoir and said cylinder through said pumpand maintaining the suction side of said Pump in constant communication with said reservoir, -a by-pass' conduit for direct flow, of fluid between said reservoir and said cylinder, manually operable means tor'controlling flow through said by-pass conduit landmanually adjustable means external of the pump body for varying the force exerted by said spring whereby the pressure in said reservoir may be adjusted to cause said ram to be projected upon opening of said by-pass conduit and to prevent flow of pressure fluid from said reservoir to said cylinder through said pump due to the pressure exerted by said spring.

JAMES P. McBRIDE.

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