US2922373A - Hydraulic pumps - Google Patents

Description

`Ian. 26, 1960 J. H, PAHL .HYDRAULIC PUMPS Filed Jan. 29,` 1958 6 Sheets-Sheet 1 IN V EN TOR. JFIMEJ l1. PAHL s IN. @Hrm AT1-onus Ys Jan. 26, 1960 J. H. PAHL 2,922,373

HYDRAULIC PUMPS Filed Jan. 29, 1958 6 Sheets-Sheet 2 SUCTION STROKE ,ALL RANGE:

INV ENTOR. JAM/5J l1. PAHL Ff@ 4 1 @@mfw ATT-oR/vs-YJ Jan. 26, 1960 J. H. PAHL HYDRAULIC PUMPS 6 Shoots-Sheet 3 Filed Jan. 29, 1958 6 EN ww S QN mv INVENTOR. 4N/EJ H. PAH/ TToANEY-J INVENTOR.

6 Sheets-Sheet 4 .ih/ws: H. PAHL.

J. H. PAHL HYDRAULIC PUMPS Jan. 26, 1960 Filed Jan. 29, 1958 MEaPREssz/RE MEoJJ/F/.ow

14 TToR/v YJ Jan. 26, 41960 J. H. PAHL 2,922,373

HYDRAULIC PUMPS Filed Jan. 29, 1958 6 Sheets-Sheet 5 ,4 T Tak/ve Y6 Jan. 26, 1960 J. H. PAHL 2,922,373

HYDRAULIC PUMPS Filed Jan. 29, 1958 6 Sheets-Sheet 6 ll/GH PRESSURE Low Voz.. FLow JA//Es h'. PA H1..

FIEL JJ www 6M A -r-roRNE Y6 HYDRAULIC PUMPS James H. Pahl, Excelsior, Minn., assignor to Rodgers Hydraulic, Inc., Minneapolis, Minn., a corporation of Minnesota Application January 29, 1958, Serial No. 712,020 11 Claims. (Cl. 103--37) This invention relates to new and useful improvements in hydraulic pumps, and more particularly to pumps capable of operating at a plurality of different effective pressures by selectively varying the volumetric flow of, the pressure fluid through the pump, and whereby the effective pressure 'of the fluid at the point of Vuse may be progressively varied in accordance with that required to accomplish the work at hand.

An object of the present invention is to provide a compact, light weight pump of very high capacity and efciency, which may readily be manually operated by the manipulation of a single operating lever to deliver the desired pressure with minimum elfort, said pump also having a single control lever for controlling the volumetric flow of the pressure fluid through the pump to selectively vary the effective pressure thereof, and whereby the pump may be operated at a given speed with a minimum required lever reaction force, and as the load demand increases, the pump may readily be adjusted to deliver a greater lifting force relative to the volume of iluid ilow without any substantial increase in the lever reaction force.

A further object of the invention resides in the novel construction of the means for relatively adjusting the operation of the valves which control the volumetric iiow of the pressure fluid to vary the working pressure of the pump.

A further and more specific object of the invention resides 'in the construction of the cam means provided for varying the volumetric flow of the iluid within the pump, such means comprising a plurality of cam elements each representing a dierent effective fluid pressure and having a control handle conveniently located on the pump housing, whereby the operator may readily and quickly shift said handle from one position to another to vary the volumetric ow and pressure of .the fluid delivered by the pump, in accordance with that required by the particular job to be done.

Other objects of the invention reside in the concentric and nested arrangement of the pistons and cylinders of the various pump means within a common cylinderforming member, thereby to provide a more compact unit; in the manner in which said parts are slidably interiitted with one another within said member; in the unique arrangement of all of the various fluid control valves and tluid circulating passages in a single valve block having means for detachably securing it to the cylinder housing, and whereby all of the valve elements and their complemental spring elements, including the valve unseating means or valve litters, may be completely assembled in said valve block before securing the valve block to the cylinder housing; and in the specilic construction of the valve-unseating mechanism, including the laterally spaced valve lifter elements and the cross head in which they Y* 2,922,373 1C@ Patented Jan.25,y 1 960 are adjustably mounted, and the operative connection between the cross head and the iuid pressure control handle conveniently located on the pump housing.

These and other objects of the invention and the means for their attainment will be more 'apparent from the following description taken in connection with the -accompanying drawings. A

In the accompanying drawings there has been disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow.

In the drawings: Figure 1 is a side elevational view of the pump with the wall of the housing partially broken away to show the pump means, the pressure relief valve, and the valve unseating means located within the pump housing, and

also showingl the fluid reservoir in the lower kportion of the housing; Y'

Figure 2 is a rear View of the pump partially broken away as in Figure l, and indicating the three positions of the pump control handle, some of the parts being cu-t away;

Figure 3 is a miniaturetop'viewof Figure 1, with the operating lever and control handlev removed;

Figure 4 is an enlarged vertical sectional View on the line 4-4 of Figure l, indicating 'thedirectional flow of the pressure Huid through the pump during the suction stroke, and when the control handle is positioned Vfor low pressure operation;

Figure 5 is a horizontal sectional view on the line 5 5 of Figure 1l, wherein the arrows indicate the directional flow of the pressure fluid in the valve block during the pressure stroke yand the two control valves are open, as when the control handle is positioned for high pressure low volume operation;

Figure 6 is a vertical sectional view on the line 6-6 of Figure 10, showing the position of the valve lifters when the control handle is positioned for medium pressure operation and wherein but one of the control valves is open;

Figure 7 is a horizontal sectional View on the line '7 7 of Figure 6, wherein the arrows indicate the directional ow of the pressure lluid in the valve rblock during'the pressure stroke and only one of the control valves is open, as when the control handle is positioned for mef dium pressure operation; Y

Figure 8 is a vertical sectional view similar to 'Figure 6, but showing the valve litters positioned for low pres-v sure operation, and wherein the two controlv valves are closed;

Figure 9 is a horizontal sectional view on the line 9-9 of Figure 8, wherein the arrows indicate the directional iiow of the pressure tluid in the valve block during the pressure stroke and the two control valves are closed, as when the control handle is positioned for low pressure high volume operation;

Figure lOis a vertical sectional view substantially on the line 10-10 of Figure 2, showing the position of the valve lifter, when the control handle is positioned for medium pressure operation, as in Figure 6; and

Figure l1 is a vertical sectional view similar to Figure 6, `showing the valve lifter positioned for high pressure operation, wherein the two control valves are open.

Housing and pump operating means The novel hydraulic pump herein disclosed is shown embodying a housing, generally designated by the numeral Z, comprising front and rear walls 3 and 4, respectively, side walls 5 and 6, and a bottom wall 7. The upper end of the housing is normally closed by a cover plate 8 securedv to the upper portions of the upright walls of the housing by suitable cap screws or bolts 9, indicated in Figures 1, 2 and 3. The cover plate 8, upright walls 3, 4, 5 and 6, and the bottom wall 7,V cooperate to provide a closed reservoir for the pressure fluid, indicated at 10a in Figures 1 and 2.

The cover plate 8 is shown providedwith an upward extension 11 which may be integral therewith. The uppermost end of extension 11 is slotted as indicated at 12 in Figure 1 to receive one end of an operating lever 13, pivoted to extension 11 by a suitable pivot pin 14. The operating lever 13 is shown provided with a cylindrical grip portion 15 adapted to be grasped by a hand of the operator.

VPump cylinder and piston assembly An important feature of the present invention resides in the novel construction of the pump means provided within the` housing and reservoir for pumping the fluid therefrom at the selected volume and pressure. The pump means comprises a cylinder-forming member, generally designated by the numeral 16, having its upper end portion ixedly secured to the cover plate 8 by suitable means such asrbolts 17. To prevent the formation of a vacuum within the housing above thelevel of the iluid, a suitable vent, not shown in the drawings, may be provided in the cover plate 8 to permit free-circulation of atmospheric air into and out of the housing during operation .of the pump. In actual operation ofthek pump, it has been found that by not utilizing a gasket between the cover plate 8 and its seat at the upper end of the housing, adequate air circulation into and out of the housing may readily be pro# vided for, as will be understood;

.Cylinder member 16 has an enlarged bore 18 at its upper end which terminates at its lower end in a reduced bore 19. Bore 19 extends to 4the bottom of member 16, as shown in the drawings. To facilitate explanation, bores 18 and l19 will hereinafter be referred to as the low and medium pressure cylinders, respectively. Cylinder member 16 also has a vertical fluid circulating passage 20 therein, the upper end of which is in direct communication with the bottom of cylinder 18. See Figures 4, 6, 8 and 11. Fluid circulating passage 20 is laterally olf-set from the aligned axes of cylinders 18 and 19. g Passage 20 serves to conduct the pressure fluid from reservoir 10 to cylinder 18 during the suction stroke of the pump, as indicated by the arrows in Figure 4. Under other operating conditions of the pump, fluid circulation through passage 20 is reversed, as will subsequently be described.

- i A valve block, generally designated by the numeral 21, subsequently to be described, is secured to the lower end of member 1 6 by suitable means such as cap screws or bolts, indicated at 21a inl Figures 5, 7 and 9. Valve block 21 provides a closure for the lower end of Ithe reduced bore or cylinder 19.

An enlarged piston 22 is mounted for reciprocalmovement in cylinder 18 and has the lower end of a piston rod 23 secured to its upper end. The upper end of piston rod 23 is pivoted to the lower end of a connecting link 24 by a pivot pin 25. The upper end of connecting link 24 is pivotally connected to the operating lever 13, as indicated at 25a in Figure 1. v

A relatively smaller hollow piston 26 has its upper end secured to piston 22 and extends downwardly therefrom into cylinder 19 in which it has the usuall piston-like t, as will be understood by reference to Figures 4, 6, v8, 10 and 11 ofthe drawings. l

Piston 26 has a relatively smaller bore 27 therein which will hereinafter be referred to as the high pressure cylinder. rIthe upper end portion of a relatively smaller fixed piston 28 is slidably received in cylinder 27. PistonZS has its lower end xedly secured -to the Valve block 21 by such means as screw threads, indicated at 29 in the drawkings. See Figures 6 and 11. e The above described parts thus cooperate to provide a plurality of piston and cylinder assemblies, in this particular instance three, all of which are axially aligned and nested, one within the other. This constitutes an irnportant feature of the invention in that it greatly facilitates the operation of machining the parts. Moreover, it results in a relatively lower and more compact and light weight unit. The enlarged cylinder 18 and piston 22 cooperate to provide the low pressure, high volume pump; piston 26 and cylinder 19 cooperate to provide the medium pressure, medium volume pump; and the fixed piston 28 and movable cylinder 27 cooperate to provide the high pressure, low volume pump.

The pressure control mechanism, subsequently to be described, selectively controls the output of the three pumps. VIt is so constructed that when positioned for low pressure high volume flow, the iluid simultaneously drawn into the three pumps during the suction stroke is directed into the delivery tube, from whence it ows to the service line. When the control mechanism is positioned for medium pressure medium volume flow the fluid in low pressure cylinder 18 is returned uninterruptedly to the reservoir whereas-only the uid from cylinders 19 and 27 is directed into the delivery tube` for subsequent delivery into the service line. This results becauserof control valve S3 being retained in open position by valve lifter 101, as

shown in Figure 6.

In like manner, when the control mechanism is positioned for high pressure low volume operation the uid contained inl the two relatively larger low and medium pressure cylinders 18 and 19 is returned directly to the reservoir during the pressure stroke, as indicated by the arrows in Figure l1, and only the fluid in the high pressurel cylinder 27 is directed into the delivery tube for subsequentdelivery to the service line. Thus, fluid is circulated freely through all pumps during each cycle of operation but only that portion of the uid delivered into the delivery tube is utilized for effecting the work operation.

Mounted within the upper end portion of the intermediate pressure piston 26 is a check valve, generally designated by the numeral 31. This valve controls the delivery of pressure uid into high pressure cylinder 27, and hasa valve head 32 adapted to engage a valve seat 33 provided at the lower end of a valve cage 34. Valve cage 34 is xedly mounted in a bore 35 in the upper end portionof cylinder 26, and is shown secured therein by the threaded extension 36 of the piston rod 23, as will be understood by reference to Figure 6. A suitable lock screw 37 may be mounted Vin the enlarged piston 22 for locking said piston to the threaded extension 36 of piston rod 23, whereby it is not likely to become detached therefrom. A brass plug 38 is shown interposed between the inner end of lock screw 37 and the periphery of the threaded end portion 3b of member 23, thereby to prevent damage to the threads thereof, as is well known in the art.

The valve cage 34 is shown provided with transverse fluid passages 39 which register with similar uid passages 41 in the upper end portion of piston 26. A suitable spring 42 is secured to the upper end of check valve 32 and constantly tends to urge it upwardly into engagement with its seat 33, as will be understood by reference to the drawings.

Valve mechanism Another important feature of the present invention resides in the unique construction of the valve mechanism for controlling the directional flow of the pressure uid during operation of the pump. The valve mechanism is best illustrated in Figures 4 to 11, inclusive, and comprises the valve block 21, in which all the valves of the pump are contained, with the exception of the check valve 32 mounted in the upper end of piston 26.

Within the valve block 21 are two horizontal uid passages 43 and 44, shown spaced laterally from one another;

, fand having their rear ends closed by suitable plugs 45, received in threaded sockets provided in the valve block, as clearly illustrated in Figures 5, 7 and 9, Plugs 46 and 47 are secured in threaded sockets provided in the bottom face of the valve block 21 with their axes intersecting the axes of their complemental iiuid circulating passages 43 and 44, as will be understood by reference to Figures 5, S and 9. Plugs 46 and 47 are each provided with fluid circulating passages 43 and 49, respectively, adapted to establish communication between the reservoir 1i? and the horizontal fluid circulating 'passages 43 and d during operation of the pump, as will subsequently be described.

Axially aligned with the fluid passages 48 and 49 in the plugs 46 and 47 are valve chambers 51 and 52. Control valves 53 and 54 are contained in valve chambers 51 and 52, respectively, and are adapted to engage valve seats 55 and 56 provided respectively at the upper ends of plugs 46 and 47, as will be understood by reference to Figures 6, 8 and ll, thereby to control fluid flow through Valve passages 4S and 49, to and from the horizontal fluid circulating passages 43 and 44.

The opposite or front ends of fluid circulating passages 43 and 44 are connected to a pair of valve chambers 57 and 58 respectively, having valve seats 59 and 61 adapted to be engaged by spring pressed check valves 62 and 63, respectively. Springs 64 constantly urge valves 62 and 63 into seating engagement with their respective seats 59 and 61, as will be understood by reference to Figures 5, 7 and 9. Valve chambers 57 and 58 are partially formed in the valve block 21 and by the counterbores provided in the inner ends of plugs 65 and 66. The inner ends of plugs 65 and 66 terminate short of the bottoms of the valve chambers 57 and 58, thereby to provide uid circulating passages between said valve chambers and a connecung fluid circulating passage 67, as clearly illustrated in Figures 5, 7 and 9, whereby the pressure fluid may ow from the horizontal passages 43 and 44 into the connecting passage 67 under certain operating conditionsvof the v pump.

It is to be understood that the upright fluid circulating passage 20 in the cylinder member 16 provides free uninterrupted fluid circulation between the low pressure cylin- Ader and the horizontal fluid circulating passage 43, and

in like manner, the lower end of the medium pressure cylinder 19 is constantly in direct communication with the horizontal fluid circulating passage 44 through an upright passage 68, shown in Figures 4, 5, 6 and-8.

Mounted in the valve block 21 in axial alignment with the fixed piston 28 is a valve cage 69 which contains a spring pressed check valve 71 which normally closes the lower end of a high pressure fluid passage 72 extending lengthwise through the fixed high pressure piston 28. The interior of the valve cage 69 is in direct communication with a uid circulating passage 73 having one end in direct communication with lthe connecting passage 67, as best indicated in Figure 5.

A delivery tube, generally designated by the numeral 74, has one end connected directly to the connecting passage 67 shown in Figures 5, 7 and 9, by a suitable fitting 75. The opposite end of tube 74 is connected to a pressure relief valve 76, best shown in Figure l. A tube 77 has one end attached to the relief valve 76 and extends upwardly therefrom through an aperture in the cover plate 8, as will be understood by reference to Figure l. The upper end portion of tube 77 is threaded as shown to receive clamping nuts 78 for securing the tube in the cover plate 8. The projecting end portion 79 of the tube 77 provides means for attaching one end of a suitable service conduit to the pump, as is well known in the art.

Control means, valve lifters, etc.

Another important feature of the present invention resides in the novel means whereby the pump may be quickly shifted from one operating condition to another by the simple manipulation of a single control handle or element. This control is generally designatedv by the numeral S1, and is shown mounted on a pivot 32 secured to the upward extension 11 of the cover plate 8.

he control handle 81 has an enlarged head 83, the periphery of which is eccentric to the axis of the head 83, as clearly illustrated in Figure 2. ".l`lne periphery of the head 83 comprises a plurality of cam faces 84, 85, and 36, each adapted to be engaged by the upper end of a valve lifting rod S7 having its upper end slidably mounted in a guide 8S forming a part of the cover plate 8. An abutment shoulder 39 may be provided on the periphery of the head 83 of the control handle 81 adjacent to cam face 84 to limit the rotary movement of the control handle in one direction, as will be understood by reference to Figure 2. The lower end portion 70 of rod 37 is threaded, as best illustrated in Figure 4, and is loosely or floatingiy received in an aperture 80, provided in a cross head 91. Lock nuts are received in threaded engagement with rod S7 and provide means for vertically adjusting the upper end of rod 87 relative to cam face S4, when the `control handle 81 is in its high pressure low volume position I-I, shown in full lines in Figure 2.

The cross head 91 extends inwardly from the rod S7 in a direction towards the valve block 21, as best illustrated in Figure l0, and has adjustably secured to its inner marginal edge portion a pair of upright guide rods or bolts 93 and 94. The lower ends of guide bolts 93 and 94 are received in threaded engagement with the cross head 91, as indicated in Figure 4, whereby they are adapted for relative vertical adjustment therein. Suitable lock nuts 95 are secured in threaded engagement with the lower terminals of bolts 93 and 94 whereby they may be securely locked in adjusted position in the cross head.

Guide bolts or rods 93 and 94 extend upwardly through suitable guide openings 96, indicated in dot-ted lines in Figures 2 and l0 of the drawings. Coiled about the upper projecting end portions `of the guide rods 93 and 94, above the valve block 21, are a pair of coiled springs 97. These springs have their lower ends seated on the top surface of valve block 21, and their upper ends are shown engaged with washers 98 seated against the heads 99 of the two guide bolts, as clearly illustrated in Figure l0.

Valve lifter rods or screws 101 and 1112 are received in threaded engagement with the cross head 91 and are adapted for independent vertical adjustment therein to assure seating of the control valves 53 and 54, as shown in Figure 8 of the drawings, when the control handle 81 is in its low pressure high Volume position L shown in full lines in Figure 2. Lock nuts 103 fixedly secure the valve lifter rods 161 and 102 in their adjusted positions in the cross head 91, whereby they are not likely to relatively shift their positions therein when the pump is in operation. The upwardly extending end portions of the valve lifter Screws 101 and 102 are freely movable longitudinally in the enlarged iiuid circulating passages 48 and i9 of control valves 53 and 54, respectively.

When the control handle 81 is in its low pressure high volume position L (see Figure 2), the upper terminals of valve lifter screws 1111 and 1132 are in their retracted positions out of direct contact with their respective control valves 53 and 54, as best illustrated in Figure 8, whereby said valves engage their respective seats at the upper ends of valve bushings 46 and 47 and thus prevent the fluid in cylinders 18 and 19 from returning directly to the reservoir 10 via uid passages 48 and 49.

To assure proper operation of the pump, the valve lifter mechanism must be so arranged and adjusted with respect to the control handle 81 that when said handle is in its low pressure high volume position L, the valve lifter pins 101 and 102; are out of direct contact with their respective control valves 53 and 54, as shown in Figure 8, whereby said valves engage their seats and prevent return flow of the pressure fluid from their respective cylinders 18 and 19 to the reservoir.

By reference to Figure 8 it will be noted that the valve lifter pins are so positioned in the cross head 91 that the upper end of valve lifter pin 101 is spaced downwardly from its closed control valve 53 just enough to permit said valve to close. The upper terminal of' valve lifter pin 102, however, is spaced a substantial distance from its control valve 54 for reasons subsequently to be described. Y

When kthe control handle 81 is shifted from low to its medium pressure position M, the relatively longer valve lifter pin 101 unseats control valve 53 to permit fluid flow from cylinder 1S to the reservoir through passage 48, as indicated by the arrows in Figure 6.- In

this position the control valve 54 remains closed because of valve lifter pin 1112 being relatively shorter than valve lifter pin 101. When the control valves are positioned as shown in Figure 6, theiiuid in the medium and high pressure cylinders 19 and 27 is forced into connecting channel 67, from whence it flows through the delivery f tube 74 Ito the service line.

When the pump is to be operated at high pressure low volume ilow, the control handle 81 is shifted to the full line position I-i, shown in Figure 2, whereupon the control valves 53 and 54 are unseated by the valve lifter pins 101 and 102, as shown in Figure l1, thereby permitting the pressure fluid in the low and medium pressure cylinders 18 and 19, respectively, to return uninterruptedly to the reservoir through the open control valves S3 and 54, upon the pressure stroke of the operating lever 1S, as indicated by the arrows in Figure ll.

When assembling the valve lifter mechanism in the pump assembly the guide rods or bolts 93 and 94 are inserted through the vertical guide opening 96 in the valve block 21, the springs 97 being iitted onto said bolts before inserting them into the vertical guides 96. The lower terminals of guide bolts 93 and 94 are received in threaded engagement with cross head 91, as hereinbefore stated, and are vertically adjustable therein to accurately space the cross head 91 from the valve block and particularly from the plane a--a of the under faces of the heads 99 of guide bolts 93 and 94, as best indicated in Figure 4. It is of utmost importance to the operation of the valve lifter that the upper surface of the cross head 91 is parallel to the plane a-a of bolt heads 99. Before mounting the cross head`91 on the valve block the operating rod 87 may be installed with its lower end 70 oatingly received in the aperture 80 in the cross head. =Lock nuts 90 on the lower end portion of valve lifter rod 87 retain said rod in its position in the cross head 91 whereby its upper terminal is properly positioned with respect to the cam faces of the control handle 81.

The valve lifter pins or screws 191 and 102 may then be vertically adjusted in the cross head and secured in fixed position therein by the lock screws 193, with their upper terminals so positioned withrespect to Vthe valve seats of the two control valves 53 and 54 that the operation of said valves, as hereinbefore stated, is assured.

To facilitate accurately positioning the valve lifter rods 101 and 102 in the cross head 91, when initially assembling the apparatus for operation, valve chamber S1, for example, may be made relatively larger than valve chamber 52 in a vertical direction, as best illustrated in Figures 4, 6 and 11. By a careful inspection of these figures it will be noted that the top wall 51 of valve chamber 51 is located at a relatively higher elevation Ithan the top wall 52' of valve chamber 52. The difference in elevations between the top walls 51 and 52 correspond substantially to the variations in the locations of the upper terminals of valve lifter rods 101 and 192.

When initially assembling the valve lifter mechanism in valve block 21, the control handle 81 is preferably positioned for high pressure low volume ow, as shown Y at H in Figure 2. The lower end of valve lifter rod 81 is then inserted in the aperture 80 in the cross head 91 and the lock nuts 90 thereon manipulated to position the cross head 91 at a fixed elevation relative to the valve seats 55 and 56.- The valve lifter rods are next vertically A Operation To initially condition the pump for operation, a suitable inelastic pressure lluid is introduced into the reservoir 10 through the ll opening, indicated at 104, in Figure 3, after which the operating lever 1S is operated through several complete strokes to make sure that all lluid circulating passages, channels and cylinders are completely filled with uid, and to eliminate air pockets from the fluid circulating system.

It is to be understood that before the cover plate S is secured in position on top of the housing, the valve lifters 101 and 102 have been checked for proper positioning with respect to their control valves S3 and 54 to make certain that when the control handle 81 is in its low pressure, L position, indicated in dotted lines in Figure 2, the control valves S3 and 54 will be engaged with their respective seats 55 and S6, as shown in Figure 8. When so positioned, the tluid in cylinders 1S and 19 cannot return directly to the reservoir through passages 48 and 49, during the pressure stroke of the operating lever 15, and is then delivered into the cross channel 67 and into the delivery tube 74 to effect low pressure high volume operation.

Low pressure-high volume Jiow When the pump is to be operated at low pressure high volume ow, the control arm 81 is shifted to the dotted -line position L in Figure 2, whereby control valves 53 and 54 engage their respective seats and prevent the uid drawn into the low and medium pressure cylinders 18 and 19 during each suction stroke (see Figure 4), from returning directly to the reservoir 11i through valve passages dit and 49, as will be understood by reference to Figure S, during the pressure stroke of operating lever 15.

AAssuming now that the operating lever 1S is in its lowered position, as shown in Figure 1, and the operator grasps lever 15 and pulls it upwardly. Such action will cause pistons 22 and 26 lto move upwardly simultaneously in their respective cylinders 18 and 19, thereby causing a suction or vacuum to develop in said cylinders which unseats control valves 53 and 54 and permits pressure Huid to be drawn into cylinders 18 and 19 through fluid passages 20 and 68, respectively, as indicated by the arrows in Figure 4.

At the same time a vacuum is formed in the high pressure cylinder 27 causing check valve 32 to open and permit pressure uid to enter cylinder 27 through passages 39 and 41 from cylinder 13, as clearly indicated by the arrows in Figure 4. During the suction stroke of the pump the high pressure check valve 71 at the bottom of passage 72 in the stationary high pressure piston 28 is closed, as shown.

When the valve lifters are positioned for low pressure, as above described, the pressure uid contained in all of the cylinders is forced therefrom into the connecting passage 67 during each pressure stroke of the operating lever 15, as indicated by the arrows in Figure 9, from whence it is forced upwardly through the delivery tube 74 and pressure relief valve 76 to the service line, not shown. Such directional flow of the pressure fluid from the various cylinders is brought about as a result of the control valves 53 and 54 being closed, as shown in Figure 8. p

Under such conditions the pressure of the duid in uidcirculating passages 43 and 44 is increased to lthe extent that the tension in springs 64 is overcome, whereupon check valves 62 and 63 open and permit the iuid in the low and intermediate pressure cylinders 18 and `19, respectively, to enter the connecting channel 67, to which the delivery tube 74 is` directly connected. At the same time the high pressure check valve 71 is unseated from the lower end of the stationary high pressure piston 28 to permit the pressure fluid in the high pressure cylinder 27 to enter the connecting passage 67 from passage 73 (Figure for delivery into delivery tube 74, as indicated by Vthe arrows in Figure 9.

When the operating lever 15 is pulled upwardly by the operator, control valves 53 and 54 will open, as shown in Figure 4, and the pressure uid then enters the horizontal fluid circulating passages 43 and 44 from the reservoir 10, through fluid passages 48 and 49, and thence ilows upwardly through passage 20 into the low pressure cylinder 18. Simultaneously, fluid is drawn into the medium pressure cylinder 19 through passage 68, as indicated by the arrow 50 in Figure 4. At the same time a vacuum develops in the high pressure cylinder 27, whereupon check valve 32 at the upper end of the high pressure cylinder 27 is opened to permit the uid to enter said cylinder from the low pressure cylinder 18, as indicated by the arrows in Figure 4, thereby conditioning the pump for the next pressure stroke.

Medium pressure-medium volume flow To operate the pump at medium pressure and medium volume flow, the control handle 81 is shifted into its vertical or intermediate position, indicated at M in Figure 2, whereupon kthe valve lifting rod 87, the upper end of which is normally retained in engagement with one of the cams 84, 85 or 86 of the control handle 81 by springs 97, moves upwardly into engagement with cam face 85 of the control handle 81. Such relative upward movement of Valve lifter rod 87 elevates cross head 91 to the position shown in Figure 6, whereby valve lifter 101 engages and unseats control valve 53. When the control valve 53 is thus unseated, the pressure fluid in low pressure cylinder 18 returns to the reservoir through passage 48 during the pressure stroke of the pump lever 15.

The suction stroke of the pump, when the latter is adjusted for medium pressure operation, is the same as when the pump is adjusted for low pressure operation. On the pressure stroke, however, the fiuid contained in the low pressure high volume cylinder l is permitted to ilow freely from said cylinder through the vertical passage 20, horizontal passage 43 and the open control valve 53 back into the reservoir. The fluid drawn into the medium pressure cylinder 19 cannot return to the reservoir as a result of the control valve 54 being closed, as shown in Figure 6. Thus, the fluid contained in cylinder 19 is forced into the connecting passage 67, as indicated by the arrows in Figure 7, and thence into the delivery tube 74. Simultaneously, the pressure huid drawn into the high pressure cylinder 27 is forced therefrom through check valve 71 into duct 73, and connecting passage 67, and thence into the delivery tube. See Figure 7.

High pressure-low volume fi'ow For high pressure low volume operation, the control handle 81 is shifted to the full line position H in Figure 2. When so positioned, the valve lifter rod 37 is elevated by the springs 97 to the position shown in Figure 1l. In this figure it will be noted that the -upper terminals of valve lifters 101 and 102 have completely unseated the control valves 53 and 54, whereby the iiuid in the low and medium pressure cylinders 18 and 19, respectively,

passages 48 and 49, as indicated by the arrows in Figure Y 10 Y 11, during the pressure stroke of the operating lever 15.

Because of the pressure fluid being thus permitted to freely escape from the low and medium pressure cylinders 18 and 19, the check valve 32 in the upper portion of the high pressure cylinder 27 is closed by spring 4Z, and as the pump lever 15 is. forced downwardly, the pressure of the fluid in cylinder 27 unseats check valve 71 at the bottom of the passage 72 of the fixed piston 28, from whence the fluid enters the connecting passage 67 through passage 73 and thence iows on through the delivery tube 74, relief valve 76, to the service line.

When the pump is not in use the control arm 81 may be in its low pressure position, indicated at L in Figure 2, but not necessarily so. There may be times when the operator may deem it advisable to leave the control handle S1 in its intermediate pressure position M, or in its high pressure position I-I. p

The pump is extremely simple and inexpensive in construction and is highly efficient in operation. The unique arrangement of the various cylinders and pistons greatly simplies construction in that the pistons and cylinders may be completely assembled on the cover plate 8 before mounting within the housing 2. In like manner the valve mechanism and valve lifter may be completely assembled independently of the piston and cylinder assembly, whereby the various valves and working parts of the valve lifter may be carefully inspected and adjusted before being embodied in the composite pump. l

The valve lifter, including the rod 87, control arm 81, cross head 91, guide rods 93 and 94, and valve lifter rods or pins 101 and 102 may also be completely assembled on the cover plate and valve block before being assembled in the housing 2,A as will readily be understood by reference to the drawings, whereby all of said parts may readily and quickly be adjusted to accurately position the terminals of the uvalve lifters with respect to their ball valves 53 and 54. In like manner the cross head 91 may readily be operatively connected to the lower end of the lifting rod S17 to assure correct operation of the control Valves 53 and 54 for the various positions of the speed control handle 81.

The housing 2 is shown provided at its lower portion with oppositely disposed leg elements 103 which are apertured to facilitate anchoring the housing to a suitable support, either fixed or portable. If the pump is to be utilized as a portable device the housing may be secured to a suitable piece of timber extending from at least the rear of the housing to a suitable distance forwardly of the housing, whereby the operator may, if necessary, place a foot on the supporting member when operating the pump.

A suitable iller plug 104 is shown provided in the cover plate 3, and a drain plug 10S is provided at the lower portion of the housing, as best shown in Figures l and 2.

Another important constructional feature of the pump herein disclosed resides in the unique arrangement of the various cylinders and pistons in the single supporting member 16. All cylinders and pistons are axially aligned with one another and are nested together to provide a very compact unit having a wide range of pressures. lThe various cylinders and piston combinations are so interconnected that they are operated simultaneously, when the operating lever 15 is manipulated. The composite pump is always available for any desired pressure within its limits by simply shifting the control handle 81 to the position representing the required pressure.

The pump has been found extremely practical and highly eicient when used in combination with other equipment requiring the use of -a pressure fluid to accomplish certain work operations. For example, the pump as herein disclosed is adapted to operate under three different working pressures, namely, 300 p.s.i., 500 p.s.i. or 10,000 p.s.i. Should the work to be accomplished require a working pressure of approximately 10,000` pounds, the pump may be quickly brought up to full or maximum 11 pressure because of the unique arrangement andconstruction of the low and medium pressure pumps, by progressively shifting the control handle S1 from its low pressure position L, through medium pressure position M, and into its high pressure position H during operation of the pump. When the control handle is so positioned, and the operating lever is actuated, the low and medium pressure cylinder and piston combinations will operate to maintain a full supply of fluid for the high pressure cylinder 27 through check valve 32, as will be understood by reference to Figure 4. In like manner, the pump may be quickly shifted from high pressure operation to a lower pressure operation without interruption.

The invention may be embodied in other specific forms without departing from the essential characteristics thereof. Hence, the present embodiments are therefore to be considered in all respects merely as being illustrative and not as being restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all modiiications and variations as fall within the meaning and purview and range of equivalency of the appended claims are therefore intended to be embraced therein.

I claim as my invention:

l. In a variable pressure hydraulic pump, a housing forming a reserv'oir having an inelastic pressure fluid therein, a cover plate secured to the upper end `of said housing and having an operating lever pivoted thereon, a cylinder-forming member secured to said cover plate and positioned within the housing, said cylinder member comprising a plurality of axially aligned cylinders, a piston mounted in each cylinder, means connecting said pistons to the operating lever whereby said pistons are adapted for simultaneous operation, a valve block secured to the lower end of said cylinder-forming member and having a plurality of fluid-circulating passages therein communicating with said cylinders, a delivery tube connected to the valve block, check valves in certain of said uid circulating passages yfor controlling fluid circulation therethrough, control valves in the valve block for controlling iluid ilow to and from said cylinders, a valve lifter mechanism for actuating said control valves to vary the elfective pressure and volumetric flow of the fluid delivered from the delivery tube, said valve lifter mechanism comprising spaced upright valve engaging elements having an operating member located exteriorly of the housing whereby the operator may conveniently manipulate said control member to cause the pump to operate at any selected uid pressure and volumetric ilow within the range of the pump.

2.. A hydraulic pump according to claim 1, wherein the valve lifter elements are adjustably supported in a common supporting member having one end of an operating rod connected thereto, the opposite end portion of said rod projecting from the housing whereby it may readily and conveniently be actuated by the operator to shift the positions of the control valves with respect to their seats, thereby to selectively vary the effective pressure of the tluid delivered from the pump.

3. A hydraulic pump according to claim 2, wherein means is mounted on the cover plate for actuating said operating rod, said means comprising a rotatably mounted member having a plurality of cam elements thereon adapted to engage said rod, said member also having an operating handle for facilitating manual shifting of said rod.

4. A hydraulic pump according to claim 3, wherein the cover plate for the housing, the cylinder-forming member, the valve lifter mechanism, and the operating lever may all be assembled as a composite workable unit prior to securing the cover plate in position on the housing, thereby to facilitate manufacture.

5. In a hydraulic pump of the class described, a housing having an inelastic fluid therein, a cover plate for 12v the housing, a cylinder-forming member secured to the cover plate and depending into the housing, said cylinderforming member comprising an enlarged low 'pressure cylinder and a relatively smaller medium pressure cylinder axially aligned with one another, pistons'l mounted in said cylinders and connected to a single operating member for simultaneous operation, the piston in said medium pressure cylinderrhaving an axial bore therein forming a movable high pressure cylinder, said high pressure cylinder having a valved connection with said enlarged cylinder, a member extending upwardly from the lower end of cylinder-forming member and providing a xed piston for said movable high pressure cylinder, a valve mechanism at the `bottom of the cylinder-forming member having a plurality of fluid circulating passages therein, a delivery tube, check valves in said valve mechanism for establishing communication between the reservoir and said fluid circulating passages during the suction stroke of the pump, control valves also in said valve mechanism for controlling the volumetric ilow of the pressure uid delivered fromthe pump and the effective pressure of said uid, and means exteriorly of the housing for t actuating said control valves to cause the pump to deliver uid at any selected pressure and volume within its limits.

6. In a hydraulic pump of the class described, a housing having a fluid reservoir in the lower portion thereof, an inelastic iiuid in the reservoir, pump means mounted in the housing and comprising a plurality of axially aligned cylinders of different diameters, a piston 'm each cylinder, an operating lever for simultaneously actuating said pistons,V valve means for controlling the flow of pressure fluid to and from the cylinders from the reservoir during operation of the operating lever, a delivery tube having one end in communication with the valve means and having means at its opposite end for connecting it to a service line, said valve means including a pair of control valves normally tending to move into closed positions, when the pump is at rest, a valve lifter operable to successively unseat said control valves from their respective seats to control the effective output of the pump, said valve unseating means comprising a vertically movable cross head having a pair of spaced upright valve engaging elements mounted therein, one for each cont-rol valve, and means operable from the exterior of the housing for manually actuating said valve lifter to unseat the control valves and thereby vary the operation of the pump.

7. A hydraulic pump according to claim 6, wherein a cam member is mounted on the upper end portion of the pump within convenient reach of the operator, said cam member comprising a plurality of cam elements adapted to engage the upper en'd of the valve lifter control rod, thereby to vertically translate the valve lifter elements in accordance to the pressure at which the pump is to be operated.

S. In a pump of the class described, a housing having a reservoir therein, an inelastic -tluid in the reservoir, a cover plate secured to the upper end of the housing, a cylinder-forming member secured to the cover plate and having its lower end portion extending into the fluid in thev reservoir, said cylinder-forming member comprising an enlarged low pressure high volume flow cylinder and a relatively smaller medium pressure medium volume ow cylinder axially aligned with said low pressure cylinder, a valve block secured to the lower end of said cylinder-forming member and having a plurality of fluid circulating passages therein, check valves and control valves in said uid circulating passages for controlling the flow of fluid to and from the cylinders from the reservoir, during operation of the pump, a delivery tube for conducting the pressure iiuid from the pump to a service line, said medium pressure piston having an axial bore therein forming a high pressure cylinder, a tubular member extending upwardly from the valve block and having its upper end slidably received in the bore in said medium pressure piston and forming a stationary high pressure piston, said high pressure piston having an axial fluid passage therein for establishing communication between the high pressure cylinder and the fluid circulating passages in the valve block, a check valve in the upper portion of said medium pressure piston for establishing communication between the low and high pressure cylinders, and an operating lever connected to said low and medium pressure pistons whereby said low, medium, and high pressure cylinder and piston combinations are actuated simultaneously to cause the pump to deliver pressure fluid from its delivery tube at a selected pressure and volumetric flows determined by the manual positioning of the control valves by the operator.

9. A hydraulic pump according to claim 8, wherein the valve block comprises av pair of horizontally disposed spaced parallel fluid circulating passages, a cross channel for establishing communication between the corresponding ends of said uid circulating passages, spring biased check valves normally closing the connection between said uid circulating passages and the cross channel, control valves in said valve block for establishing communication between the reservoir and said horizontal iluid circulating passages, a delivery tube having one end in communication with the cross channel and its opposite end projecting from the housing and adapted to be connected to the service line, and a valve lifter for actuating the control valves, thereby to selectively control the effective pressure and volumetric flow of the fluid delivered by the pump.

10. A pump according to claim 9, wherein a fluid circulating duct connects the lower end of the axial iluid passage in the xed high pressure piston to said cross channel, and a normally closed check valve in the valve block for controlling the flow of high pressure fluid from thev high pressure cylinder to said cross channel at low volume, when the control valves are unseated by the operator, thereby to cause the uid in the high pressure cylinder to enter the cross channel and delivery tube.

11. In a pump of the class described, a housing having an inelastic fluid therein, a pump body, a plurality of iluid circulating pumps in said body each comprising a cylinder and piston, all of said cylinders and pistons being axially aligned with one another and nested together to provide a compact unitary structure, an operating member at the upper end of the housing for simultaneously actuating all of said pumps, a valve body secured to the lower end of the pump body and having laterally spaced horizontal fluid circulating passages therein, a channel for establishing communication between the corresponding ends of said fluid circulating passages, check valves in said uid circulating passages for permitting one way flow of the fluid from said passages into said connecting passage, said connecting passage having one end of a delivery tube in communication therewith the opposite end of which is adapted to be connected to a service line exteriorly of the pump housing, a control valve in each yfluid circulating passage for controlling fluid llow from the reservoir thereinto when the pumps are operated, means for manually successively unseating said control valves to control the ow of iluid from the reservoir into said horizontal uid circulating passages, said valve unseating means being manually operable to selectively control the unseating of said-control valves to cause the composite pump, when operated, to deliver pressure luid to the service line at a selected effective pressure and volumetric ilow, depending upon the positioning of the control valves by said valve unseating means, said valve unseating means comprising spaced parallel upright valve lifter elements, one for each control valve, a supporting member for said valve lifter elements, spring biased guide rods adjustably secured in said supporting member and slidably received in guides in said valve body, an operating rod for the valve lifter having its lower end floatingly engaged with said supporting member, and means at the upper end of said rod for vertically translating it to shift the positions of the valve lifter pins and thereby raise or lower the control valves relative to their seats, thereby to vary the effective pressure and volumetric flow of the fluid delivered by the pump.

References Sited in the file of this patent UNITED STATES PATENTS 468,104 Weeks Feb. 2, 1892 833,457 Hammond Oct. 16, 1906 867,932 Weeks lOct. 8, 1907 947,613 Gathmann Jan. 25, 1910 1,080,062 `'Hess Dec. 2, 1913 2,044,857 Pfauser June 23, 1936 2,311,468 Pfauser lFeb. 16, 1943 2,442,058 Page May 25, 1948

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