US2250551A - Pump for hydraulic jacks - Google Patents

Description

July `29 1941-' E. M. PFAUSER 2,250,551-

' l PUMP FOR` iYDRAuLIc JAcKs Filed July l, 1938 QN www vw mm, Nm/ Y w 4 N. 2f v Patented July 29, 1941 PUMP FOR HYDRAULIC JACKS Edward M. Pfauser, (trove,` Wis.,assignor to Blackhawk Mfg. Co.,"`'Milwaukee, Wis., a corporation of Wisconsin Appueetien .my i', 1.938, serial lNe. zi6,9o9

f2' My present invention relates generally -im' provements in hydraulic jacks, and relates more specifically to improvements in the construction and' operation of multiple speed jacks of 'the type wherein the'lii'ting head may be quickly x5 draulic lacks, `Whih iS .autmatically Operable initially positioned in contactv with the work,

'and thereafter most eiectiveiy applied at reduced speed to actually perform its duty.

It has heretofoiebeen proposed as shownin",10 23,1932, to provide a-hydraulic type of service,

my priorfPatent No.1,8"l3,473, 'granted August jack for garages or the like, wherein the lifting head may be rapidly elevatedto position the same in initial contact with the work,with the aid of a relatively large low pressure pump, and in which the load is automatically transferred A j to a smaller high pressure pumpwhen the resistance .to .continued elevation of thehead-is increased. While this t of. ack has roven ype j p the portable type;A

highlypractical and satisfactory in commercial use, it requires the application of considerable excess power to operate the lower pressure pump against the retarding pressure when the high pressure pump is in action during nal lifting ofthe work. This feature is not seriously ob- L jectionable when liftingI light loads, but is quite 7 Clarins?` '(01:103-42) `pumps from 'excess pressure, when another of 1 the pumps becomes active.

Another specific' object of lthis invention is to.

provide an improved unloading device for hyby pressure resulting from loading the jack.

These and other objects and advantages of my present invention vwill be apparent from the following'. detailed description. e

A .clear-conception of one practical embodiment of theinvention, and of the mode of constructing and of operating'hydraulic jacks built inaccordance with the improvementfmayH-be vhadbyreferring to the drawing accompanying l5 and forming a part of this speciiication, wherein like reference characters, designate the same or similar parts in the several views. 3 Fig. 1 is a central longitudinal vertical section through-a typical two speed hydraulic jack-of' Y Fig. 2 is an enlarged part sectionaltopview of a portionof the lack assemblage'adjacent to the rearmheels; and .f I Fig.` 3 is a similarly enlarged transverse vertical section taken throughthfe supplyreservoir and control valves of the jack. Whiletheinventionhas-been shown andldescribedherein. as being embodied in a two speed y portable garage-type of hydraulic jack, it is not Ithe intention to thereby unnecessarily restrict the scope, sincethe improved unloading device may bemorergenerally applicable to other types of -fluid pressure'actuatedjacks.

Referring toithedrawingrthe portable hydraulicejack assemblage'. illustrated therein co .prisesnn'general a horizontally elongated frame essary for operating the-high pressure pump. In an effort to cbviate this objection, I later provided a-spring pressed by-pass valve i the circuit of the large low-pressure pump, loaded to a predetermined pressure, andadapted to -par-` tially relieve the pressure in the large pump when the small pump was working under high pressure, as) shown in Patent No. 2,044,8'5'7, grant-` ed June 23, 1936. While this improved construction was a vast improvement over the original two speed lack, it'was still somewhat'objection-r able since it did not-.entirely relieve helarge' pump from retardingpressure while" he' other pump was operating under highppressure, diieV to the predetermined loading oi the bypass valve.

it is therefore an object of my present-,inventionto provide a multiple pump hydraulic lack of the general type above referred to,:wherein one oi' the pumps is entirely relieved of retarding under hish pressure. r A :more specic object of the invention is to provide improved control mechanism for a hy.-

i draulic iackywhich will lfunction to automat? consistingfof`.a.pair of laterally spaced similar e opposite -side beams or plates-Shaving -a power unitcasing. interposed between and rigidly front...supporting wheels 14er the mein frame attached.' tor the rear-portionsfof the plates l;

mounted upon anaxlerrear caster wheels l pivotallysuspended -from brackets I0 formed integralY with the Side plates i; a lifting 'arm Il' swingablysuspendedat one end from the medial hevingeneend pivoteuygeeseeiatea with th'e mainframe and .its opposite vend pivotally attached to the carrier socket for the saddle ,13;

'a1 mQti0n.-impartins`plunger. is elidable' in-*the icalLv relieve one ofl aplurality of" actuating casing land having its outer end cooperablijfwigh Y,

upper1 portionsof the frame plates i by meansl head orsaddleJ pivotally supported at the op pressure, when the other or others are operating. 50 posits end thereof; Aa. para11e1 kmaiden :link la.

a roller I6 carried by the arm I I remote from the pivot pin I2; a tension spring I1 for constantly urging the roller I8 in contact with the plunger I6; an oil supply reservoir I8 of ample capacity formed in the casing 6 above and laterally adjacent to the hydraulic displacement chamber i9 of the plunger I6 which is alsoformed in the casing 9; a high speed pump plunger 20 coacting with a bore `2l in the casing 6 and being reciprocable through links 22 by means of a handle 23 pivotally suspended from the rear of the casing 6; a pressure or slow speed pump plunger 24 rigidly attached to the casing 6 and slidably coacting with a central bore 25 formed in the reciprocable plunger 20; valve mechanism for controlling the delivery oi.' liquid from the reservoir I6 through the pumps to the chamber I9; and a release valve 26 for permitting return of liquid from the chamber I9 to the reservoir I8 during lowering movement of the arm i I. C

The general construction of the jalck is well known, and. constitutes no part of my present invention, and the improved valve mechanism for the pumps is clearly shown in Figs. 2 and 3. 'I'he liquid supply reservoir I8 which is formed in the power unit casing 6, i-s provided with two relatively deep wells 21 which are connected through strainers 29 and a horizontal passage 29, with vertical ports 30, 3I of which the large port 36 is controlled by a ball suction valve 32 while` the smaller port 3l is likewise-controlled by a small ball suction valve 33. The port 30 is communicable past the valve 32 and through a passage 34, with the bore 2| constituting the speed pump displacement chamber, and this displacement chamber is also communicable through a similar passage 35 with one side of a discharge valve 36 the opposite side of which communicates` chamber I9, independently of .the connection of the speed pump therewith. The pressure rey lease valve 26 for normally relieving the pressure from within the chamber I9, is disposed in a conduit 4I which connects the passage 40 with thereservoir I8, and .the release valve 26 may be held in closed position by means of a rotary to thereby move the lifting plunger I6 in a for-l ward direction.

'I'he chamber 46 in which the suction valve 32 is located, and which is'consta'ntly in communica- Ition 'with the speed pump bore 2I through the passage '34, is provided with a limit stop member 49 and is communicable past this member with a passage 41 formed in an unloading valve casing P1l3. An unloading valve 49 which is normally pre'ssedto its seat by a. spring 56, is adapted to open when' the pressure in the bore 2I reaches a predetermined value, so as to permit fthe liquid from the speed pump to escape to the reservoir I8, thus preventing the speed pump plunger 28 from being subjected to pressure above a deilnite predetermined value, at any time. While the spring 5.0 determines the maximum pressure to-which the speed pump plunger 20 can be subjected. the valve 49 is also adapted to be positively opened and to be held in open position so as to further relieve the pressure Within the bore 2I, when the pressure pump is effective in lifting the work, by means of a piston 5I, slidable in a bore 62 in the casing 48 and having a stem 53 adapted to ,this valve as the plunger 20 reciprdcates. When the piston 5I is in its extreme lower position, the lowerface seats against the tapered seating on the casing 48 and prevents high pressure fluid from escaping past the piston. The unloading device therefore functions to positively unseat the valve 49 and to hold it open, when the pressure in the displacement chamber I9 and conduit 54 is suillcien't to move the piston 6I against the action of the spring y66 to a position wherein the stem 53 will engage and unseat the valve 4 9; and when the pressure in the chamber I9 falls below the predetermined value iixed by the tension of the spring 55, then the spring 69 immedialtely becomes effective.

The chalnber 56 Within which the dischargev valve 36 is located, and which is in constant communication with the displacement chamber I9 through the passage 31, is likewiserprovided with a limit stop member 61 and is communicable past this member with a passage 68 formed in a safelty valve casing 59. A poppet type of safety valve 60 is mounted in the casing 69 and is normally held to its seat by means of a coil spring 6I which is of sulcient strength to establish a predetermined high pressure within the chamber I9. When this maximum pressure is.exceeded, the safety valve 60 will automatically open to permit liquid to escape from the chamber I9 through the passage 31, chamber 63 and passage 58 to thereservoir 'I8.- The chamber 92 within which the pressure pump discharge valve 39 is located, is also provided with a limit stop member 63, and the valves 32, 33. 36, 39, 4,9 are obviously accessible for inspedtion upon removal of their normal conilning members. The liquid supply reservoir I8 is provided with a removable cover 84, and all of the plungers I6, 29,24 are provided with suitable packings adapted to be lubricated .by the liquid such as oil from the reservoir I 8.

During normal use of the improved jack assemblage, and when4 the de ce is not ln actual operation, the plugv 42 is withdrawn to permit free opening ofthe release .valve 23, and the lifting arm Il is in lowered position resting against the frame stops. The lifting "ram or plunger I5 will then be pushed rearwardly into the displacement chamber I9, and thehandle 23 and pump plunger 20 may be either in the position shown in Fig. 1 or in any other desired position. If it becomes desirable to elevate the arm II and saddle I3, it is only necessary to turn the knob 44 to positively close the release valve 29 with the aid of the plug 42, and to thereafter oscillate the handle 23 so as to reciprocate the speed pump plunger 20 through the links 22. The plunger 20 during its rearward stroke will then draw liquid from the reservoir I3 through the passages 29, 30 past the suction valve 32, and through the chamber 45 and passage 34 into the bore 2i; and during the forward stroke, the plunger 2li will force this liquid through the passage 35 past the discharge valve 36, and through the chamber 56 and passage 31 into the lifting plunger chamber I9, providing no Work is being engaged by the saddle I3. During this initial reciprocation of the plunger 2li, liquid will also be drawn from the reservoir IB through the passages 29, 3i past the small suction valve 33, and through the passage 39 into the pressure pump bore 25 during the rearward stroke of the plunger Y 20; and will be forced [by the fixed plunger 24 out of the bore 25 through the passage 38 past -the discharge valve 39, and through thelpassage to the displacement chamber I9, obviously causes the plunger i5 to move forwardly at a rapid rate, and quickly lifts the arm II and saddle I3 until the) latter engages an obstruction.

When the saddle I3 is subjected to-excess pressure such as an object which is to be elevated,

the hydraulic pressure withinfthe chamber I9 is quickly increased by the ram or plunger I5, and

subsequent forward movement of the plunger 2li will augment this pressure, and will cause the valve 49 to be automatically opened against the action of the spring 50. The increase in pressure in the chamber I9 will be transmitted through the conduit 54 to the piston 5I, and will force the latter downwardly against the action of the spring 55 until the piston seats against the casing 48 and the stem 53 unseats the valve 49 and holds the same open. The valve 49 will then be held open as long as the pressure in the chamber I9 and connection 54 is suilicient to produce such action, but when this pressure drops so as to enable the spring 55 to elevate the stem 53 out of contact with the casing seating and'valve 49, this valve will again .be seated by the spring 5l. When the valve 49 is thus opened, the large annular face of the plunger 20 which surrounds the fixed plunger 24,will obviously be entirely relieved of pressure. and will thus permit oscilla- .tion of the handle 23 with minimum eilort.

After the saddle I3 has engaged the work, the pressure pump continues its delivery of liquid from the reservoir I 8 into the displacement chamber I9, and the lifting plunger I5 will continue to travel forwardly `but at a considerably reduced rate of speed. If, however, the pressure in the chamber. I9 reaches the maximum value xed by the spring 6I of the safety valve 50, then the valve will be opened by this high pressure acting through the passage 31, chamber 59 and passage 53,and excess pressure will be sure within the bore 2i when the work isbeing lifted, reduces theI force required to oscillate the handle 23 to a minimum when the pressure pump is active in lifting objects,- and the improved unloading device obviously functions to quickly relieve the larger area of the plunger 20 fromexcessive pressure when the saddle I3 engages the work. Inorder to subsequently lower the arm II and the saddle I3, it is only necessary to manipulate the knob 44 so as to withdraw the plug 42 and release the valve 26, whereupon the liquid from within the chamber I9 returns to the reservoir I9 through the passages i0, 4I.

From the foregoing detailed description it vwill be apparent that my present invention provides an extremely simple yet highlyeffective unloading device for multiple speed hydraulic jacks. which effectively relieves-the actuating handlev from excessivenpressure due to the continued operation of the speed pump while work is being performed with the jack. The unloading piston- 5| is rapid and automatic in its action by virtue of its being exposed Ato the interior of the chamber I9 at all times, and when the valve 49 is 1inseated or opened, the speed pump is made inactive without interferring with the normal opera-4 tion of the pressure pump. It will be apparent thatthe release of this pressure acting on the relatively large area of the speed pump will materially reduce the effort necessary to actuate the pressure pump when extremely heavy objects are being lifted with the jack, and the present improvement has proven highly satisfactory in actual use and may obviously be conveniently applied to hydraulic jacks of the general type shown herein with the addition of very few and relan to limit this invention 'to the exact details-of construction or to the precise mode of use. herein lshown and described, for various modifications within the scope of the claims may-occur to persons skilled in the art.

` movable in opposition to its seating spring di-y relieved to the reservoir I8. While the plunger apparent, however, that the release of the pres- I claim:

1. In combination, a large displacement pump, a small displacement pump, means for simultaneously operating said pumps, means forming a space for` receiving fluid from bothpumps, a fluid supply reservoir, an unloading valve interposed between Isaid reservoir and the displacement chamber" of said large pump, said valve being operable directly by excessive pressure in said chamber to permit escape of fluid to said reservoir, and a plunger operable by pressure in said space to open said valve.

2. Incombination, a large displacement pump, a small displacement pump, means for simultaneously operating said pumps with equal strokes, means formingv a space for receiving liquid from both pumps, a liquid supply reservoir. a spring seated unloading valve interposed between said reservoir and the displacement chamber of said large pump, said valve normally being rectly by excessive pressure in said chamber to permit escape of liquid to said reservoir, and a spring restrained plunger operable by excessive pressureA in said space to opennsaid valve independently of the pressure in said chamber'.

3. In combination, a large displacement pump,

. a small displacement pump, said pumps having coaidal pistons andv cylinders and 'being simultaneously operable with equal strokes, means forming a space for receiving liquid from both pumps, a liquid supply reservoir, an unloadinx valve normally operable by excessive pressure in the displacement chamber of said large pump to permit escape-of liquid from said chamber to said reservoir, and means operable only by excessivel pressure in said space to open said valve independently of the pressure in said chamber.

4. In combination, a large displacement pump, a small displacement pump, said pumps having coaxial pistons and cylinders and being simultaneously operable with equal strokes, means forming a space for receiving liquid from both pumps, a liquid supply reservoir, a spring seated unloading valve normally operable by excessive pressure in the displacement chamber oi said large pump to permit escape of liquid from said chamber to said reservoir, and a spring restrained plunger operable only by excessive pressure in said space to open said valve independently of the pressure in said chamber.

5. In combination, a large displacement pump, a small displacement pump, said pumps having simultaneously operable coaxial pistons, means forming a space for receiving liquid from both` of said pumps past their respective discharge valves, a liquid supply reservoir communicable with both o f said pumps past their respective inlet valves, an unloading valve normally operable only by excessive pressure in the displacement chamber of said large pump to permit escape of liquid from said chamber to said reservoir, and a plunger constantly exposed to the pressure in said space and being operable by excessive pressure in the latter to open said unloading valve independently of the pressure in the displacement chambers of said pumps.

6. In combination, a large displacement pump, a small displacement pump, means for simultaneously operating said pumps, means forming a space for receiving fluid from both pumps, a fluid supply reservoir, a poppet type unloading valve interposed between said reservoir-,and the displacement chamber of said large pump, said valve being operable directly by excessive pressure in said chamber to permit escape of fluid to sadreservoir, and movable means operable by pressure in said space to open said valve.

7. In combination, a large displacement pump, a small displacement pump, means for simultaneously operating said pumps, means forming a space for receiving liquid from both pumps, a liquid'supply reservoir, a'spring seated poppet type unloading valve interposed between said reservoir and the displacement chamber of said large pump, said valve normally being movable in opposition to its seating spring directly by excessive pressure in said chamber to permit escape of liquid to said reservoir, and a spring restrained plunger operable by excessive pressure in said space to open said valve.

EDWARD M. PFAUSER.

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