US1669976A - Pump - Google Patents

Description

May 15, 192s.

I A. L. DE LEEUW PUMP Filed Dec. 2s. 192s 4 Sheets-Sheet 3 Patented May l5, 1928.

ADOLPH L. DE LEEUW, 0F PLAINFIELD, NEW JERSEY.

Application filed December 23, 1926.

This invention deals with fluid pumps of that type adapted to provide either a continuous flow of fluid, in varied amounts as may be required, or which, by adjustment, may be rendered ineffective to deliver fluid, without discontinuing the movement of the pump actuating mechanism. Pumps of this nature have heretoforebeen provided but they have been more or less unsatisfactory in that they were complicated in construction; costly to manufacture; ditlicult to assemble and provided no adequate means to take up the lost motion th'erein produced by the inevitable wear in the parts.

T his invention has for an object to render available a fluid pump of this nature which will be simple in construction and which will be relatively inexpensive to manufacture, the parts being few in number and of such form that they readily may be Inachined and assembled. This object of the invention has been attained by constructing a pump with a cylindrical body portion adapted to be closed by suitable end plates. Substantially all of the operating parts within the casing are of circular form which permits them to be formed and finished in automatic machines at a very nominal cost.

A further object of the invention is to provide improved actuating means for the various pistons, which will apply its power more directly to the pistons and therefore will operate with greater efiiciency than have prior devices. To this end the cylinders (of which there are two series) are arranged in pairs with their axes in alignment, each pair of cylinders constituting, in effect, a single bore. The pistons of the two series are arranged in the opposite ends of said bore and are actuated toward a common exhaust port by annular cams having their workingl faces acting upon said pistons directly in line with their axes, whereby the pistons are given their Working stroke without any cramping or binding action in the cylinders. Improved anti-friction connections also are provided between the pistons and their actuating cams to reduce friction.

Still another object is to provide iniproved means for varying the effective stroke of the pistons whereby any desired flow between zero and maximum may be secured. inasmuch as two pistons operate in a single cylinder bore each piston forms in effect a cylinder end-wall toward which its Serial No. 156,582.

complemental piston moves, thereby effecting fluid discharge. It will readily be perceived that if one piston were maintained stationary the amount of fluid displaced per reciprocation would be determined by the diameter and stroke of the complemental piston toward the exhaust port, which is located intermediate the adjacent ends of the pistons. Likewise if the two pistons are simultaneously moved toward each other each piston will ejecta predetermined amount of fluid, or in other words the flow will then be doubled. Furthermore, if the pistons are timed to reciprocate in like directions simultaneously there will be no relative movement between the pistons and their respective cylinder end-Walls (which is the end of the other piston) and therefore no fluid will be ejected. Thus it will be perceived that although the pistons may be given strokes of predetermined length the effective stroke of each-piston will be dependent upon its relative movement with respect to its complemental piston. The last named object is attained by providing a positive throw cam for each series of pistons and providing an angular adjustment for one of said cams whereby the cams may be timed either to exert their maximum throws in opposite directions upon complemental pistons, to effect maximum pump displacement or the cams may be adjusted angularly as much as 180 apart so that the complemental pistons will be timed to move in like directions, thereby eliminating relative movement between them and reducing pump displacement to zero. Obviously any desired flow between zero and maximum may e obtained by relative angular adjustment letween the cams. ugllrlejfmeralglytliacanas.are ,n

force in one direction/only and the pistons are kept in contact with the cams by reason of the fact that fluid is admitted to the intake port under suticient pressure to insure retraction of the pistons as the working face of the cam recedes therefrom, all as will hereinafter be more fully explained.

A still further object of the invention is so to form the parts of the improved pump that they readily may be assembled, adjusted into working relation after they have been assembled, and maintained in that relation over a great period of time regardless of the usual and unavoidable wear on the parts. This 8 formed in a statiiiaiivalvf"i'atemy iwithin the body portionyfhla has been attained by so forming the parts that they all may be assembled merely by movement thereof in the direction of the axis of the actuating 'shaft which extends into the casing. One of the cams is adapted to be secured to one of the end plates before that plate is secured in position on the casing. Adjusting means is provided exteriorly of the/casing for moving the parts axially into working relation after the parts have been assembled. This adjusting means also enables the operator occasionally to effect a slight adjustment of the parts to compensate for wear, whereby the pump will be maintained etlicient in action.

Other objects and advantages will be in part indicated in the following description and in part rendered apparent therefrom in connection with the annexed drawings.

To enable others skilled in the art so fully to apprehend-the underlying features hereof that they may embody the same in the various ways contemplated by this invention, drawings depicting a preferred typical construction have been annexed as a part of this disclosure, and, in such drawings, like char- Iacters of reference denote corresponding parts throughout all the views, of which Figure 1 is a` side elevation, partly in section of a pump embodying the present invention. Fig. 2 is longitudinal section thereof, the cylinder blocks,- pistons and actuating cams being shown in elevation. Figs. 3, 4;, and 5 are transverse sections on the lines 33, 4-l, and 5-5, respectively, of Fig. 1. Fig. 6 is a central longitudinal section of a preferred construction, showing mleans for effecting ready assembly of the parts and for taking up lost motion caused by wear therein. Fig. 7 is a transverse section on the line I1-7 of Fig. 6.

Referring more particularly to the embodiment of this invention illustrated in Figs. 1 to 5, inclusive, the improved pump is constructed with a cylindrical body portion 1 closed at its opposite ends by plates 2 and 3. ,These elements form a. closed casing adapted to house all of the operating mechanism of the pump, which mechanism is actuated from a rotary shaft 4 extending longitudinally through said casing. The body portion 1 is provided at diametrically opposite sides with inlet and outlet pipes 5 7 ld d '"e'mvalip'late lmay be located axially of the casing, with the intake and exhaust ports in registry with inlet and outlet pipes, by being abutted against an annular shoulder 10 and it may be held against angular movement by a pin 11 inserted in an aperture formed partly in the body portion and partly in the valve plate, as shown in Fig. 4. The valve plate municate witlldlllet and outlet ports Waterlanderregenerate erinnere with two series of bores a andy `',"'r"spectivelyi`,"`

constituting pump cylinders. The bores a and ZJ are arranged about the axis of the shaft t and in pairs with their axes in alignment and are adapted to receive complementalv` pistons@` andd. These pistons are given reciprocatory mtiousw iii their respective cylinders successively to effect intake and exhaust of the iiuid.

An important feature of this invention resides in the means for giving the pistons their axial movements to effect the discharge of fluid from their respective cylinders. ln accordance with the present invention this is eected by normally stationary cams 16 and 17 each of which has an annular working face in alignment with the pistons and which, during rotation of the cylinder blocks, shifts the pistons axially. To reduce frictionl the cams preferably act upon the pistons through the intermediary of an antifriction member carried by each of the pistons, and to provide a full working contact of substantial area between the cam and anti-friction member the face of the cams are preferably bevelled and the anti-friction members are in the form of truncated conical wheels 19 arranged with their greater diameters outermost from the axis about which they revolve. lVith this construction a full working contact is maintained between each wheel and its cam and no slippage is -pro` duced, although the outer periphery of the vwheel necessarily revolves in a circle sub- To steady the pistons and to hold them and 6 respectively, and $1165@ wpipgwmswagainst turning about their longitudinal axes the innermost portions of the bifurcated ends 20 are of arcuate form, as shown at in Fig. 3, and lit the cylindrical outer periphery y of the reduced hub port-ions of the cylinder blocks 14 and 15.

It is to be noted that the cams 16 and 17 electmovement of the pistons in one direction only i. e. in the direction to elfect exhaust of the fluid from the cylinders d and- I). Movement of the pistons in the opposite direction, to maintain the rollers in'contact with the cams as the working faces thereof retract from the rollers, is effected by the fluid which enters the pump under pressure through the inlet pipe 5.

supposing iirst:-that the cams 16 and 17 are so positioned angularly" about the shaft 4 that their high points 16 and 17X are in opposition i. e. they are arranged to operate simultaneously on aligned complemental pistons c and Z for maximum vdelivery; second, that the shaft 4, and cylinder blocks 14 and 15 are being rotated in the direction of the arrow in Fig. 4; and thirdfwthat the high points of the cams are located at opposite sides of the partition 12a of the valve plate. the operation of the pump will be as follows As the aligned cylinders pass from the partition 12a and through the positions a1, a2, and a3 in Fig. -4 the pistons will be retracted by the pressure of the fluid in the loading chamber 12, the rollers 19 following the declining faces 16d, and 17d of the cams 16 and 17. The low points 16y and 17y of the cams are arranged adjacent the partition 12b and when the cylinders have reached that position the pistons will have been fully retracted and the cylinders filled with fluid supplied to the loading chamber under pressure. As Vthe cylinder blocks rotate to bring the cylin`` ders adjacent the exhaust chamber 13 the rollers on the pistons ride up the inclined side 16 and 17u of the cams and therefore the opposed pistons are forced toward each other thereby simultaneously ejecting, from their cylinders, the Huid therein which is lpassed outwardly through the delivery pipe 6. This advancing movement of the pistons is continued while the cylinders are passing through the positions, a4, a5 and a6 and unt-il the rollers again reach the high points of the cams adjacent the partitions 12a. The high and low points of the cams are prefer-- aligned cylinders will exhaust into the other and no fluid will be delivered through thev pipe 6.

Figs. 2 and 5 show the preferred means for effecting angular adjustment of one of the cams. The cam 17 is rotatably mounted in the casing as by being journaled on the shaft 4 and is formed with a toothed annular flange 17 f, which is in the nature of a worm wheel. A worm 22, fixed upon a manually rotatable shaft 23, journaled in the body portion 1 of the casing, meshes with the worm wheel 17f and serves to adjust the position of the cam 17 when. the shaft 23 is rotated manually as by means of a hand wheel 24.

Figs. G and 7 show a preferred embodiment of this invention which more readily may be assembled and which provides means for adjusting the parts into working position after they have been assembled and for effecting adjustments of the parts to compensate for wear. The pump illustrated in these two figures is similar in construction and identical in operation with the pump hereinbefore described. In so far as the parts are the same as those previously described they have been designated by the same reference characters. In this embodiment the body portion 1 of the casingis formed with an annular {iange 1a to which is secured as by bolts 1", a similar iange provided by a sublcasing 3a. This sub-casing forms a closure for one end of the body portion and provides a bearing 40. for the free end of the drive shaft 4a (which in this pump terminates within the pump-casing) and also a hub 41 upon which. the cam 17 is rotatably journaled. The other end of the body portion 1 of the pump -casing is closed by an end plate 2a provided with a stufling box 2b through which the drive shaft projects. Adjacent the end plate 2n the drive ably short flats which permit ..Slighlldwell`shaft is formed with an annular shoulder in the movement of the pis ons, as they are passing thev partitions 12a and 12b when the cam 17 is adjusted 4for lmaxirn'um delivery.

Should it be desired to reduce the output of the pump one cam may be adjusted angularly to vary the time of reciprocation of one series of pistons with respect to the other series, whereby one piston will have completed its forward movement and started to retract while its complemental piston is still advancing, whereupon the advancing piston will exhaust into the cylin- I der of the retreating piston and the amount i Y pipe will be reduced.

of Huid forced out through the delivery An extreme adjustment of the cam is 1800 which places the high point of one cam in opposition to the low point ofthe other, whereby each piston of one series is receiving its exhaust stroke, While its complemental piston is receiving its' intake stroke,l therefore one of the 4S which contacts with the plate and prevents relative axial movement in one direction between the casing and the shaft. Vithin the sub-casing 3l the shaft 4a is formed with a thrust collar 42' adapted to bear against an anti-friction thrust bearing 43 interposed between said collar and the hub of the cylinder-block 15. A similar thrust bearing 44 is located between the hub of the cylinder block 14 and the base of the cam 16, secured to the end plate 2,

yThe cam 17 is adapted to be adjusted ansecured to the sub-casing. A stuffing box 49 carried by the bearing` bracket 48 prevents leakage about the shaft 23. Movement of the shaft 23 in the opposite direction is prevented by an anti-friction thrust bearing 50 engaging the end of the shaft and adjustable axially of thel shaft by a screw 51. A lock nut 52 on the screw prevents accidental rotation of the screw and thereby holds the thru-st bearing in any desired position of adjustment.

It is to be noted that, like the pump illustrated in F igs. 1 to 5 inclusive, substantially all of the parts of this pump are of such form that they readily may be formed and finished by turning operations in automatic machine tools, thus providinga structure which may be built at a very nominal cost.

Referring now to Fig. 6 it will be seen that this pump very readily may be assembled as follows: First the thrust bearing 43 may be slid on the shaft 4n from the left end thereof and placed in contact with the collar 42. Then the cylinder block 15, fitted with the pistons d, may be slid into place from the left; likewise the valve plate 9, cylinder block 14 with the pistons a and thrust bearing 44. Then the end plate 2R, to which the cam 16 has previously been secured, may be placed upon the shaft from the left. rIhe body portion 1 of the casing may then be slid over the above mentioned parts from the right and attached to the end plate by screws s. Now the sub-casing 3a, which has previously been fitted with the cam 17, and the adjusting` means therefor, is placed in its operative' position and secured to the body portion 1 by screws 1b.

The parts are now assembled but the operating parts are not necessarily in working relation. To effect this final step in the assembling of the pump it is merely necessary to turn the screw 53, threaded through the sub-casing- This screw bears against an adjustable thrust bearing 54 which engages the free end of the shaft 4a. Rotation of the screw 53 in one direction pushes the thrust bearing 54, shaft 4a, collar 42, bearing 43, cylinder block 15, valve plate 9, cylinder block 14, and thrust bearing 44 to the left and simultaneously draws the sub-casing 3a, body member 1, end plate 2f. and cani 16. to the right thereby bringing the parts tightly together. The screw 53 may then be backed off a `small fraction of a rotation to relieve the clamping action and the parts will be maintained in Contact but freely rotatable. A lock nut holds the screw 53 against accidental rotation and maintains the parts in working relation.

The head of the screw 53 is accessible from the outside of the pump and therefore for wear. These adjustments will gradually move the valve plate 9 out of contact with theshoulder 10 as shown at 56 in Fig. 6 but it will be held aga-inst rotation by a pin 11 as shown in Fig. 4.

From the foregoing it will be perceived that this invention provides a pump which is extremely simple in construction, which may be manufactured at a very low cost, which readily and easily may be assembled; which admits of adjustment to compensate for wear; which applies power more directly and more efliciently to the pistons, and which readily may be adjusted to vary pump displacement.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying` current knowledge, readily adapt it for various utilizations by retaining one or more of the features that, from the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention and, therefore, such adaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the followingclaims.

Having thus revealed this invention, I claim as new and desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent of the United States 1. A pump combining two series of aligned cylinders adapted to be revolved about a common axis; pistons slidable in said cylinders; an intake having fiuid connections to the cylinders of both series; an exhaust having fluid connections to the cylinders of both series; stationary cams mounted in said pump acting directly upon said pistons in line with their axes to give to said pistons strokes of constant length; and means to adjust the position of one of said cams with respect to the other to vary the eective action of said pistons, thereby to vary the delivery of the pump.

2. A pump combining two aligned cylinders; pistons slidable in said cylinders; intake and exhaust ports common to and having iuid connections to both of said cylinders; means simultaneously to give to said pistons opposed strokes of predetermined length to effect maximum pump delivery; and means to change the timing of the stroke of only one piston to vary pump delivery.

3. A pump combining two aligned and connected cylinders; pistons slidable in Said cylinders; fluid exhaust and inlet means for said cylinders; cams mounted on said pump to act on said pistons simultaneously to give to said pistons oppositely directed movements thereby to exhaust fluid from said cylinders simultaneously to effect maximum delivery; and means to adjust one cam to cause one piston to receive its delivery stroke during the intake stroke of the other thereby to negative fluid delivery.

4. A pump combining two aligned cylinders; pistons slidable in said cylinders; a common intake port, said pistons being simultaneously retracted by the incoming fluid therethrough; a common exhaust port having fluid connections to both of Said cylinders, means to cause said pistons simultaneously to be advanced to expel the contents of said cylinders through said common exhaust port; and means acting on, only one of said pistons to vary the time of advance and retraction of one of said pistons with respect to the other to cause one of said pistons to exhaust a portion of the contents of its cylinder into the other cylinder thereby to reduce pump delivery.

5. A pump combining two aligned cylinders; pistons slidable in said cylinders; intake and exhaust ports common to both of said cylinders; annular cams, provided with high and low points cooperating with said pistons; means to effect relative rotation between said cams and said pistons whereby the pistons are moved axially, said cams normally being positioned with their low points adjacent said intake port to permit the pistons to be retracted and the cylinders to be filled with fluid entering through said intake port, and with their high points adjacent the exhaust port to cause the pistons simultaneously to exhaust the fluid from their respective cylinders; and means for adjusting one of said cams angularly to cause the intake of one cylinder to overlap in action with the exhaust of the other and conversely.

6. A pump combining a closed casing; a rotary actuating shaft extending into said casing; two cylinder blocks within said casing provided with two series of aligned cylinder-bores arranged about the axis of said shaft; complemental pistons slidable in said bores and movable toward each oth-er to eject fluid; a valve plate intermediate said cylinder blocks and provided with intake and exhaust ports for said cylinders; an actuating cam for the pistons in each cylinder block, said cams each being provided with an annular working face arranged in line with the axis of said pistons; means to eect relative rotation between the cylinder blocks and piston and said cams to effect reciprocation of said pistons; and means to adjust one of said cams angularly to vary the time of reciprocation of one series of pistons with respect to the time of reciprocation of the other series.

7 A pump combining two cylinder blocks each provided with a series of cylinder bores, the cylinder bores of one series being aligned with the cylinder bores of the other series; pistons slidable in said cylinder bores; intake and exhaust ports having fluid connections to both seri-es; anti-friction devices carried by said pistons; a cam in contact with the anti-friction devices of each series; means to effect relative rotation between said cylinder blocks and pistons and said cams thereby to effect reciprocations of said pistons; and means to vary the timing of one cam with respect to the other.

8. A pump combining a casing; a rotary shaf't extending into said casing; a valve plate secured within said casing and provided with intake and exhaust ports; a cylinder block fixed to said shaft at each side of said valve plate, said cylinder blocks being in contact with said valve plate and provided with a plurality of aligned cylinders adapte-d to communicate with said ports upon rotation of the blocks; pistons slidable in said cylinder; an annular cam fixedly secured within said casing at one side of said valve plate and adapted, during the rotation of said cylinder blocks to effect axial movement of the pistons in the cylinder block; a similar cam adjustably mounted in said casing at the other side of said valve plate and acting during the rotation of the cylinder blocksl to efiect axial movement of the other pistons; and means 'to adjust the position of said last named cam to vary pump displacement.

9. In a pump, a cylinder, a piston slidable in said cylinder; an annular cam provided with a working face inclined to a line perpendicular to the axis thereof, an anti-friction roller, carried by said piston, and tracking the working face of' sai-d cam, said roller having its periphery inclined to correspond to the inclination of the working face of the cam; and means to effect relative rotation between the cam and the cylinder to effect axial movement of the piston, said working face and periphery being inclined thruout their extent in such direction that the diameter of said roller increases outwardly to thereby compensate for the outwardly increasing path of said roller on said cam.

10. In a pump, a cylinder; a piston slidable in said cylinder; an annular cam having a working face inclined outwardly and downwardly from the axis thereof; a truncated roller journaled on a pin carried by said piston, said roller having its greater diameter outermost from the axis of said cam and its periphery in contact with the working face of said cam, the inclination of said cam and roller being such as to substantially compensate for the gradually increasing length of path for the outer portions of the roller; and means to produce relative rotation between the cam and the cylinder to effect axial movement of the piston.

11. In a pump, a cylinder block provided with a plurality of cylinders arranged about the axis thereof; pistons slidable in said cylinders; a cam having an annular face in contact with said pistons; means to eifect relative rotation between the cam and pistons about th-e axis of the cam thereby to effect axial movement of the pistons; and means to prevent rotation of the pistons about their own axes comprising a cylindrically shaped guide projecting axially from said cylinder block, and a bearing member fixed to each piston having an arc-shaped surface adapted to engage said guide.

l2. In a pump, a casing; a .shaft journaled in said casing; a cylinder block fixed to said shaft and rotatable therewith; a cylindrical hub on said cylinder block; cylinders formeil in said cylinder block; pistons slidable in said cylinders and each provided with a bi-A furcated end exterior-ly of said cylinders; rollers journaled in said bifurcated ends; and a normally stationary cam in said casing and a-dapted to act upon said rollers during rotation of said cylinder block to effect axial movement of said pistons; a portion of said bifurcated ends being shaped to fit against the hub of the cylinder block to prevent rotation of the pistons as they are axially moved.

13.- A pump combining a cylinder; intake and exhaust ports adapted alternately to be connected with one end of said cylinder; a piston slidable in said cylinder; an annular open face cam having advancing and retreating portions; said advancing portion acting upon said piston at the end remote from the intake and exhaust ports and substantially in line with its axis; a fluid pressure line connected with said intake port to supply fluid thereto under pressure; means to effect relative rotation between said cam and said piston to cause the retreating portion to pass said piston; means to connect said cylinder with the intake port during the passage of the retreating portions past the piston, the fluid under pressure flowing into said cylinder and retracting said piston thereby maintaining it in contact with said retreating portion and loading said cylinder; and means to disconnect the cylinder from the intake port when the retreating portion of the cam has passed the piston and for maintaining the .exhaust port connected therewith during the action of the advancing` por-tion on the piston.

14. A pump combining a housing comprising a substantially cylindrical body portion and an end plate and a sub-casing removably secured to the opposite ends of said body portion to form a closed structure; a plurality of pump cylinders and pistons within said housing; cams within said housing adapted to actuate said pistons; a valve-plate within said housing adjacent said cylinders for controlling the admission and exhaust of fluid thereto; a. rotating shaft extending into said housing and operatively connected to effect relative rotation between the cams and the pump cylinders and pistons therein to cause said cams to effect axial movement of said pistons; and means exteriorly of the housing to adjust said cams, cylinders, pistons, and valveplate into sufficiently tight engagement for working operation after they have been assembled in said housing.

l5. A pump combining a casing; rotatable cylinder blocks in said casing provided with two series of aligned cylinderbores; opposed pistons slidable in said bores; a valve plate intermediate said cylinder blocks and havingintake and exhaust ports common to the cylinders of each block; a stationary cam arranged adjacent one cylinder block acting7 during the rotation of said cylinder blocks, to effect translation of one series of pistons; a normally stationary cam arranged adjacent the other cylinder block acting during rotation of said cylinder blocks to effect translation of the corresponding series of pistons; a manually rotatable shaft journaled in said casing; and a threaded connection between said shaft and the last mentioned cam to permit said cam to be adjusted relative to the first mentioned cam to vary pump delivery.

16. In a pump, a drive shaft formed with a collar; a thrust bearing surrounding said shaft and maintained against axial movement by said collar; a first cylinder block adapted to be slid lengthwise over said shaft and into contact with said thrust bearing and provided with a plurality of cylinders; pistons in said cylinders; a valve plate adapted to be slid over said shaft and into contact with said cylinder block; a second cylinder block adapted to be slid upon said shaft and into contact with said Valve plate, said second cylinder block having cylinders aligned with the rst named cylinders; pistons in the last named cylinders; fluid inlet and outlet passages in said valve plate adapted to communicate with said cylinders; a second thrust bearing on said shaft in contact with said second cylinder block; a casing end plate provided with an annular cam adapted to be slid over said shaft and into contact with said thrust bearing; said cam being adapted to act on the pistons in said second cylinder block; an open ended casing body portion adapted to be slid over said cylinders and into contact with said end plate; means to secure the end plate to one end of said body portion; a closure section adapted to be secured to the other end of sald body portion to form a closed casing; an annular cam within said closure section and adapted to act on the pistons of the first cylinder block; and means to adjust said Vao parts into the desired degree of engagement after they have been assembled in said closed casing.

17. A pump combining a closed casing; an inlet pipe and an outlet pipe connected therewith; fluid displacement means including cylinders, pistons and actuating cams within said casing having valve means and fluid .connections for receiving fluid from said inlet pipe and expelling it through said outlet pipe; and means accessible from the exterior of said casing to adjust said parts axially into working relation after they have been assembled and for taking up wear therein.

18. A pump combining a closed casing; an inlet pipe and an outlet pipe connected therewith; fluid displacement means including cylinders, pistons and actuating cams within said casing having valve means and fluid connections for receiving fluid from said inlet pipe and expelling it through said outlet pipe; and means including an adjusting screw threaded through said casing and acting in opposite directions on said displacement means and said casing for adjust` ing the parts into propell axial working relation after they have been assembled.

19. A pump combining a casing; a rotating drive-shaft extending into said casing; two cylinder blocks splined to said driveshaft; cylinders formed in said cylinder blocks; pistons movable in said cylinders; a valve plate non-rotatably held in said casing between, and in Contact with, said cylinder blocks and free to be moved axially; intake and exhaust ports formed in said valve plate and cooperating with the cylinders in both cylinder blocks; a cam arranged axially adjacent each cylinder and adapted to actuate the pistons therein; and means for adjusting said cylinder blocks and valve-plate axially toward one of said cams to compensate for wear.

20. A pump combining a casing; a plurality of cylinders mounted in said casing; a valve-plate provided with loading and discharge chambers connected, respectively, with intake and exhaust ports; partitions separating said chambers; pistons slidably mounted in said cylinders; a piston-actuat ing cam having an irregular face comprising a declined portion adapted to permit said pistons to be retracted when adjacent said loading chamber, an inclined portion adapt ed to advance said piston when adjacent said discharge chamber; and neutral portions, between said inclined and declined portions,

adapted to produce a dwell in the movement of said pistons as they are adjacent said partitions; and means to eect relative rotation between the cam and valve-plate and said cylinders.

21. A pump combining a casing provided with a cylindrical bore; a rotary drive shaft extending into said cylinder; a plurality of annular cylinder blocks arranged Within said bore and fixed to rotate with said shaft; cylinders formed in said cylinder blocks; an annular valve plate fitted within the cylindrical bore of said casing and engaging the adjacent ends of said cylinder blocks, said valve plate being provided with intake and exhaust ports and loading and discharge chambers co-operating with said cylinders; pistons slidable in said cylinders; annular face cams normally fixed within said casing and acting upon said pistons substantially in line with their axes to reciprocate them toward said discharge chamber to exhaust the fluid from said cylinders, said valve inlet port and loading chamber providing means for admitting fluid under pressure to retract said pistons when adjacent said loading chamber to cause said cylinders to be loaded.

22. A pump combining two aligned cylinders; pistons therein; fluid inlet means having connections arranged to simultaneously admit liuid under pressure t0 both cylinders to cause the simultaneous retraction of the pistons; exhaust means having connections to both of said cylinders; means to cause said pistons normally to be simultaneously advanced to expel the contents of said cylinders through said exhaust means; and means to vary the time of advance and retraction of one of said pistons whereby a portion of the contents of one of said cylinders is exhausted into the other thereby to reduce pump delivery.

23. A pump combining a main body member; a cylinder therein, said member and cylinder being relatively rotatable; fluid inlet and exhaust connections for said cylinder; an annular cam carried by said member having a working face inclined outwardly from the cam axis and away from said cylinder; means for adjusting said cam about its axis relative to said member; a piston in said cylinder; and a truncated roller carried by said piston adapted to track said annular cam.

In witness whereof, I have hereunto subscribed my name.

Y ADOLPH L. DE LEEUW.

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