US2945451A

US2945451A - Hydraulic motor and/or pump

Info

Publication number: US2945451A
Application number: US349787A
Authority: US
Inventors: David E Griswold
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-04-20
Filing date: 1953-04-20
Publication date: 1960-07-19
Anticipated expiration: 1977-07-19

Description

July 19, 1960 Filed April 20, 1953 D. GRlswoLD HYDRAULIC MOTOR AND/OR PUMP 5 Sheets-Sheet 1 ATTORNEYS July 19, 1960 D. E. GRlswoLD 2,945,451

' HYDRAULIC MOTOR AND/0R PUMP Filed April 20, 1953 5 Sheets-Sheet 2 INVENTOR wvl'ai E. rs'wald BY 5M ATTORNEYQ` July 19, 1960 D. EGRlswoLD 2,945,451

HYDRAULIC MOTOR AND/OR PUMP Filed April 20, 1953 5 Sheets-Sheet 3 July 19, 1960 D. E. GRlswoLD 2,945,451

HYDRAULIC MOTOR AND/OR PUMP Filed April 20, 1953 5 Sheets-Sheet 4 #a fof July 19, 1960 D. E. GRlswoLD HYDRAULIC MOTOR AND/0R PUMP 5 Sheets-Sheet 5 Filed April 20. 1953 INVENTOR E. rllfw ATTORNEYS United States Patent le() HYDRAULIC MOTOR AND/ OR PUNIP David E. Griswold, '2330 Monterey Road,

San Marino, Calif.

Filed Apr. 20, y1953, Sel. N0. 349,787V 1s claims. (ci. 10s- 114) The present invention relates to a rotary-type fluid operated device of the positive displacement type, and includes elements adapted to be arranged so that the device may be used either as a motor or a pump.

The principal object of the invention is to provide a Vrotary-type iluid operated motor wherein the eciency is extremely high and leakage past the motor and/ or pump pistons is practically negligible.

A further object of the invention is to provide a pump structure adaptable for use as a one-way pump, and by slight modification adaptable for 4use as a reversible, or two-way, pump.

A further object of the invention is to provide a rotarytype fluid motor or pump wherein the parts are arranged and constructed so that a minimum power loss occurs through friction.

Another object of the invention is to provide apump or motor construction in which the crankcase is substantially filled with a lubricant, and wherein means is provided for preventing excess pressure from being developed in the crankcase.

A more specific object of the -invention is to provide a novel eccentric construction and method of making the same.

Another specific object of the invention is to provide a novel, yet simple means of assembling a shaft and roller with a piston of a rotary pump or motor.

Other objects of the invention will be apparent from Vthe following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional View through a reversible fluid-operated motor embodying the principles of the present invention; p

Fig. 2 is a fragmentary sectional view taken on the line 2.-2of Fig. 1 looking in the direction of the arrows;

Fig. 3 is a transverse sectional view through the motor taken on the line 3-3 of Fig. l;

Fig. 4 is a perspective view of one of the pistons of the motor, and particularly illustrating the band employed to prevent inadvertent disassembly of the roller and wrist pin associated with the piston; Y

Fig. 5 is a fragmentary sectional View taken on the line 5--5 of Fig. l;

Fig. 6 is a view of the seat for the valve which controls the distribution of lluid to the rnotor cylinders, as viewed on the line 6--6 of. Fig. l;

Fig.A 7 is an enlarged fragmentary sectional view through the fluid distribution valve;

Fig. V8 is a plan view of the valve as viewed along the line 8-8 of Fig. 7;

Fig. 9 is an inverted plan view of the valve as viewed on the line '9-9 of Fig. 7;

Fig. 10 is a horizontal sectional view taken on the line 10-10 of Fig. 7;

Fig. 11 is a vertical sectional view through a portion of the valve body taken on the line 11-11 of Fig. 10;

Fig. 12 is a horizontal sectional view through the same portion of the valve body shown in Fig. 11, but taken on the line 12-12 of Fig. 7;

Fig. 13 is a longitudinal sectional view through a reversible pump embodying a structure similar to that shown in the aforedescribed figures, but including a modified type of piston adapted to minimize the air space in its associated cylinder; and

Fig. 14 is a longitudinal sectional view of a pump similar to that shown in Fig. 13, but adapted to serve only as a one-way pump.

Referring now more particularly to Fig. 1, the reference numeral 1 generally indicates a housing or casing of a motor M, preferably made of bronze or any other suitable corrosion resistant metal, Vand provided with five radially extending cylinders 2, each provided with a radial bore 3. Any suitable number of cylinders may be provided and the provision of live such cylinders in the present motor is merely illustrative of a simple but preferred form of the invention. A piston 4 is disposed in each of the cylinder bores 3 and is radially slidable therein. Each bore 3 .is provided with a groove 5 in which a sealing member in the form of a conventional O-ring 6 is disposed. The exterior surface of each piston 4 is hardened Vand ground so that it has a smooth, close sliding fit in its associated bore 3. The O-ring 6 engages the hardened and ground outer surface of the piston 4 and provides a fluid-tight seal therewith.

Each piston 4 has a flat head 7 and has its weight reduced by drilling a hole 8 axially of the piston from its inner end 9 and by milling a slot 10 diametrically of said inner end and in intersecting relation with the hole' 8. The slot 10 has a width slightly greater than the diameter of the hole 8, as is clearly shown in Fig. l. The inner end 9 of the piston 4 is of reduced diameter as indicated at 11 and is provided witha chamfer 12 at its extreme inner end and with an undercut groove 13 at a region spaced inwardly from said chamfered portion. The transverse slot 10 divides the inner end of the piston into a pair of diametrically opposed ears 1'4, and both ears are provided with a diametrically aligned opening 15 for the reception of a wrist pin 16. Each of the Wrist pins 16 is made of steel, hardened and ground to have a close tit in the openings 15.

A roller assembly 17 is mounted upon each of the wrist pins 16 and comprises a roller portion 18 and a bushing 19 disposed in concentric relation with a plurality of antifriction rollers 20 disposed therebetween. Retainers 21 are received in Iseats partially formed in the roller portion 18 and bushing 19 and serve to retain the rollers 20 in place. The bushing 19 has oil passageways 22 extending therethrough to provide for access of oil from within thehousing 2, to the rollers 20. The wrist -pin 16 is maintained in assembled relation with the piston 4 by-a brass band 23, which is slipped over the inner end 9 of the piston 5 on to the cylindrical portion 11 of reduced diameter until one edge thereof engages the abutment formed by the undercut groove 13. The chamdistorted at diametrically opposed sides into a flattened or straight condition, as indicated at 2'4 in Fig. 4, in the Yregion thereof which spans the slot 10. The band 23 is then positively lixed on the piston 4 by inwardly bending the portion thereof in the region of the undercut groove 13 as indicated at 25 in Fig. 1. Thus, the roller assembly 17 and the wrist pin 16 are maintained in more or less permanent assembly with the piston 4, without any danger of the parts becoming inadvertently disassembled while jthe motor is in use. Y

Still referring to Fig. 1, the housing 2 has a circular opening 26 formed at one side thereof and a closure plate or cover 27 is provided with a circular boss 28 received in said opening for centralizing said closure plate with respectl to Asaid housing. A ,gasket 29 is interposed between a flange 30 ofv the closure member 27 and the adjacent side of the housing 2,'to form a liquid-tight seal therebetween. The housing 2 is further provided with a plurality of threaded openings 31 adapted to receive cap screws 32 extending through the flange 30 for detachably securing the cover member 27 to the housing 2.

The housing 2 is further provided with a wall 33 disposed in confronting relation to the bossY 28 of the cover 27 and with an axially extending wall 34 which cooperates with thewall 33 and cover 27 to form a crankcase or lubricant reservoir 35. The wall 33 has an axial opening 36, which is enlarged as indicated at 37 to receive a conventional ball bearing 38. The cover 27 has a complementary axially disposed opening 39 for the reception of a conventional ball bearing 40. VA shaft 41 extends through the opening 36 in the housing wall 33 and through an opening 42 in the cover 27 and is supported for rotation relative to said housing and 40, respectively. The shaft 41 has a peripheral groove 43 formed therein in a reduced region thereof received within the housing opening 36 and a conventional rubber O-ring `44 is disposed in said groove to form a fluid-tight seal between the shaft 41 and the housing 2. The shaft 41 is also of reduced diameter in the region thereof disposed outwardly of the ball bearing 40, and a conventional packing 45 including sealing elements 46 and 47 engaged with the shaft 41 provide a double seal, the packing 46 having a lip disposed to prevent fluid from escaping from the crankcase 35 along the shaft 41, and the packing `47 having a lip disposed to preventforeign matter from entering the crankcase 45 from the. exterior of the cover 27. The sealing member 45 Vis mounted in a shouldered recess 48 formed in the cover 27. A flange 49 is formed on the cover 27 for mounting the motor upon any device which is to be driven by the shaft 41, the outer end of said shaft projecting beyond said flange for convenient connection with such device.

An eccentric generally identified by the numeral 5,0 (Figs. l and 3) is mounted on the shaft 41 between a pair of spacer rings 51 and 52 loosely mounted onl said shaft adjacent the ball bearings 38 and 40, respectively. The eccentric 50 comprises an eccentric collar 53, which is press-tted on the shaft 41 in a predetermined relation to provide the desired degree of eccentricity. A hole 54 is then drilled through both the collar 53 and the shaft 41 and a dowel pin 55 is driven into said hole to prevent relative rotation between the collar and shaft. A steel ring 56 is then axially pressed onto the collar 53 and has the same width as the collar 53, and' obstructs both ends of the hole 54, so that the pin 55 cannot possibly work its way out of the hole 54- to disrupt the.

driving connection between the shaft41 and the collar 53.

The outer periphery of the ring 56 engages the periphery of the several rollers 13 and is preferably hardened and ground to assure smooth operation and long wear. The ring 56 has a theoretical line contact with the rollers 18 and the rollers inherently remain aligned in the same transverse plane as the ring 56, so that there is no tendency for the pistons 4 to rotate at any time in their respective bores 3.

Referring to Fig. l, the housing 2 has an axially extending cylindrical wall 57 providing a valve chamber 58. A manifold 59 is secured to the outer end of the wall 57 by a plurality of cap screws 60, a gasket 61 being interposed between the wall 57 and manifold 59 to provide a liquid-tight seal. The manifold 59 has `an axially extending passageway 62 which communicates at 1ts outer end with a supply conduit 63 containing fluid under pressure and secured to the manifold by a memcover by the inner races of the ball bearings 38 and i ber 64 mounted on the manifold by cap screws 65. The manifold 59 is further provided with five ports 66 (see Fig. 5), equally angularly spaced radially and all parallel with the axially extended passageway 62. The outer end of each of the ports 66 is intersected by a radial passageway 67 having a conventional fitting 68 soldered and pressed therein as indicated at 69.

Each of the cylinder bores 3 (Fig. l) is closed at its outer end by a head 70 secured in place by a plurality of cap screws 71, a gasket 72 being interposed between each cylinder head and the adjacent cylinder end to form a fluid-tight seal. Each of the cylinder heads 70 is provided with a passageway 73 having its inner end communicating with its associated cylinder and having a conventional fitting 74 mounted in its outer end and press-fitted and secured in place by solder, as indicated at 75. Each of the manifold fittings 68 is interconnected with a cylinder head fitting 74 by a conduit 76 secured to the respective ttings by

conventional fastening elements

77 and 78, respectively. Thus, one conduit 76 connects each cylinder of the motor with one of the ports 66.

A balanced pressure fluid distributing valve 79 is disposed in the pressure chamber 58 and is adapted to control the supply and exhaust of operating fluid, successively, to each of the cylinders 3. This valve will be described in detail later. The housing wall 57 has an outlet opening 80 which communicates with a discharge conduit 81 connected with a member 82 secured to the wall 57 by cap screws 83. The exhaust or spent operating liuid from all of the cylinders is discharged from the chamber 58 through the discharge conduit 81, as will be apparent hereinafter.

The present motor is adapted to be operated by any suitable liquid under pressure, preferably one which will not have an objectionable corrosive effect upon the metal. For example, water, light oil, kerosene, or gasoline may be employed as the motivating liquid. Heavy oils may be used but preferably are avoided because they result in sluggish action. A light oil is the preferred operating medium inasmuch as it can also serve as a lubricant.

`The manifold 59 has a passage 85 communicating with the passageway 62 in which a conventional fitting 86 is mounted. One end of a conduit 87 is secured to the fitting -86 yand the opposite end of said conduit is connected to a conventional fitting 88 mounted in a passage way 89 in the housing 2. The passageway 89 is shouldered to providea seat `for a ball-check valve 90 and a compression spring 91 is disposed .between the ball 90 `and the inner end of the fitting 88. The purpose of the ball-.check valve 90 `is to relieve any excess pressure that vmay .develop inthe lubricant in the crankcase chamber 35. A second ball-check valve 92 is mounted in a passageway 93 :formed in thefhousing 2, the outer end of .the passageway 93 lhavin-g a hollow screw 94 mounted therein and a compression spring 95 disposed between said ball Vand screw. The check Valve 92 will open to .relieve excess pressure in the same manner as the check valve 90, Abut the discharge lthrough the passageway 93 enters the chamber 58 for final discharge through the exhaust conduit 81;

The valve 79 comprises a body or disc portion 100 and a cover 101 is secured to a radial flange 102 ofthe body 100 by .a plurality of screws 103. A diaphragm 104 is disposed between the flange 102 and the cover 101 and forms a iiuid-tight seal therebetween. The cover 101 has a central aperture 105 intol which one end of the drive shaft 41 projects; A diametrically extending slot 106 intersects the opening 105 and a drive-pin 107 carried by lthe shaft 41 is received in said slot for drivingly interconnecting shaft 41 and the -iiuid'distribution valve 79.

-The distribution valve 79 is generally similar to the `balanced valve disclosed in the `patent to Donald G.

Griswold, 21,545,774, granted March 20, l951.l However,

the present valve involves certain improvements over the valve disclosed in said patent, as `will appear more fully hereinafter.

The details of construction of the valve 79 are best illustrated in Figs. 7 to 12, inclusive. The valve body portion or disc 100 includes a lower cylindrical portion 108 having a 'face 109 at the lower end thereof which engages la lapped seat 110 mounted on the manifold or base member 59. -It will be observed that the fi-ange 102 is counterbored at i111 .to provide a chamber 112 at the lower side of the `diaphragm 104 adapted to receive a circular, stiff brass plate 113. The counterbored area V1111 is provided with two recesses 114 for the reception of two light springs 115 which engage the lower side of the plate 113 and normally urge the same into contact with the lower side of the diaphragm 104. The cover member i101 is similarly counterbored to provide a chamber 116 (similar to the chamber 112) above the diaphragm 104. Openings y1-17 extend through the cover 101 to Iestablish free communication between the chamber 116 andthe pressure chamber 58 (note Fig. 1). A circular plate 1:18, similar to the plate `113, is disposed in the chamber 116 between the diaphragm 104 and the adjacent end -face of the shaft 41.

It will Ibe noted from Fig. 9 that a circular port 119 extends axially inwardly from the face 109 and that an elongated arcuate port 120 extends inwardly from the same face, the two ports being merged by a recessed portion or chamber v121, which interconnects the same within the disc 100 .and extends downwardly from the counterbored portion 111. A second arcuate port 1 22 also extends inwardly from the face 109 and is formed on the same radius and has Ithe same arcuate length as the port 120. The port 122 communicates with the chamber 58 in the valve body 57 through openings i123 formed in the side wall of .the cylindrical portion 108. The adjacent rounded ends o-f Ithe arcuate ports `120 and 122 are formed upon radii spaced 30 on either side of a diametrical line x, as indicated in Fig. 12. I

The porting of the seat 110 is best illustrated in Fig. 6. lit will be noted from this figure and Fig. 1, that a seat port 1124, of the same diameter as Ithe disc port 119, is arranged in axial alignment with said disc port and with the passageway 62 in the base 59. The seat 110 is further provided with five ports 125 aligned with the base ports 66 and arranged parallel with the port 124 and drilled on Ithe same radius as that of the arcuate ports 120 `and 122 of the rotary disc 110, thus assuring registration of the ports in said base and disc to effect the desired 'working cycle of lthe motor M.

The 4driving of the motor shaft 41 under the control of the rotary valve 79 is effected by the successive registration of the

disc ports

120 and 122 with the ports 125 of the seat 110 for successively admitting operating fluid into the cylinders 2 and exhausting operating fluid from said cylinders to actuate the pistons 4 to cause the rollers 18 associated therewith to exert force on theeccentric 50 to rotate the shaft 41 to drive any device connected therewith exteriorly of the cover 27. The valve 79, of course, is driven by the shaft `41 through the connection provided by the pin 107 and slot 106.

Fig. 13 illustrates .the manner in which the motor M Y described hereinbefore can be modified to make it serve as a reversible pump P. The only changes required eccentric 50 to serve as a driver lfor the modified pistons.

Thus, the axial bore Sis omitted from the piston, here identified by the numeral 4a, and a recess 150 of sub stantial depth is formed in the outer end of the piston, Vthus providing a cylindrical wall 151 of substantial height.

A filler member 152 is disposed in the recess 150 and 4"has a flange i153 at its inner end to maintain the same fcentralized in 'the recess 150. A compression'spring 154 is disposed in the cylinder 2 between theange 153 and the cylinder head 70, and between the outer periphery of the filler member -152 and the inner surface of the wall 151, and serves to maintain the roller18 en- `gaged ait all times with the ring 56 of the eccentric 50.

The head 70 has a `cavity 70a to receive the filler member' 152, which is of greater length than the depth ofithe recess 150. It is to be understood that .all five pis tons of .the device conform with the foregoing description so that each cylinder acts in succession as a pumping cylinder.

When the device is modified to serve as a pump, the shaft 41 is either manually driven, or driven by a motor or other prime mover, not shown. When the valve 79 is rotated relative to the seat 110, suction is produced in the conduit 63, through the conduits 76 as the pistons ,4a are successively retracted or forced inwardly by the springs 154 as permitted by the eccentric 50, so .that the liquid to be pumped is drawn into the valve 79 and passes therethrough to the .particular cylinders =2 whose pistons 48 are being retracted under the infiuence ofthe springs i154. Correspondingly, the conduit 81 'becomes a discharge conduit for liquid successively forced out of the cyilnders 2, by outward radial movement of the pistons 4a by the ececntric 50, it being understood that the fluid distribution valve 79 is rotated simultaneously with the shaft .41 .to successively position the inlet port v and the outlet port y122 thereof in registration Awith the seat ports 125 and the ports 66 in the manifold l59.

The pump illustrated in Fig. 13 can be made to' operate in a reverse manner, by positioning the valve assembly 79 so that it is 180 out of phase with respect to its previous position. When the angular relation of the valve 79 is thus changed relative to the drive shaft 41, the functions occurring in the pump are reversed. 'I'hat is to say, the cylinder which would ordinarily be receiving operating fluid under pressure is4 o'pen to exhaust and vice-versa. Correspondingly, a suction is then created in the conduit 81 for drawing the liquid to be pumped into the cylinders 2, and the liquid forced out of the cylinders 2 by the pistons 4a is discharged through the conduit 63. The ball-check valves 90 and 92 prevent excess pressure from being built up in the crankcase 35 irrespective of the direction in which the shaft 41 is being rotated.

It is to' be understood that the device illustrated in Fig. 13 can be used as a motor instead of a pump, should such operation be desired. This would mean, of course, that with the valve 79 in one operative position fiuid under pressure would be introduced through the conduit 63 into the chamber 121 and distributed by the valve 79 successively to* the various cylinders 2 to provide hydraulic power for forcing the pistons 4' radially inwardly and in this manner cause the rollers 18 acting on the eccentric 50 to effect positive rotation of the shaft 41. Exhaust or spent operating fluid would then be discharged through the

ports

122 and 123 of the valve 79 into the chamber 58, the same as described in co'nnection with the motor shown in Fig. l, and eventually discharged through the conduit 81. Moreover, the direction of rotation of such motor can be reversedby shifting the position of the valve 79 thro'ugh an angle of 180 relative to the shaft 41, and then supplying operating fluid under pressure through the conduit 81, with the ultimate discharge thereof as'exhaust through the conduit 63. irrespective of'the direction in which the device of Fig. 13 is operated, the additional resistance offered by the springs is insufficient to effect the practicability of the use o'f the device as a motor instead of a pump,

since the spling forces are distributed about the axis of the shaft 41 and offset each other.

Fig. 14 illustrates a device similar to that shown in Fig. 13, except that the ball-check valve 92 has been omitted, thus rendering the device useful as either a oneway pump, that is, a uni-directional pump, or as a one- 7 way bruni-directional Imotor. In either event, the valve 79 'functions the sameas previously `described herein to control the distribution fluid to and from the cylinders 2.

Hydraulic motors Aand pumps constructed in accordance with the principles of the invention are about 95 Vto 9% eicient, the loss in eiiiciency being attributable mainly to expansion of the parts during o'peration and the compression'of Vair in the operating fluid or liquid being. pumped.

It will be understood that the present motor and/ or pump utilizes the medium being handled as a lubricant in the crankcase 35. Thus, the present device is ideal `for -being operated as a motor by a light oil or for pumphaving a crarikcase and a plurality ofY cylinders disposed radially relative to said crankcase; a head closing the outer end 4ofeach cylinder; a shaft extending through said crankc'ase and being rotatably supported in said housing; a piston in each of said cylinders; a pin carried by each of said pistons adjacent the inner end thereof; a roller mounted on each pin; an eccentric secured to Vsaid shaft and engageable by the rollers of the respective pistons, the cylinders providing the only guide means for the pistons and rollers whereby said pistons are free in their associated cylinders to allow said rollers to automatically adjust themselves to make substantially line contact with the outer periphery of said eccentric, each of said pistons having a wall portion defining a recess in the outer end thereof; a filler member substantially'iilling each recess, said filler member having a portion thereof removed to provide an annular space disposed inwardlyof the portion of the piston wall defining lsaid recess; and a compression spring mounted in each annular space having one end thereof engaged with a head and its other end engaged with a filler member.

2. In a device of the character described, a casing having a cylinder provided with a bore; a head closing one end of said cylinder; a piston in said bore having the end thereof adjacent said head recessed; a ller member in said recess substantially filling said recess and'having a ange adjacent the bottom of said recess providing an annulus between the filler member and the wall of said recess; a spring in said annulus between said flange and head normally urging said piston in a Adirection 4away from said head; means to conduct fluid to and from said cylinder in cyclically timed relation with the reciprocation of said piston; a shaft rotatably mounted in said casing; and means establishing a driving connection between ysaid piston and shaft.

3. In a device of the character described, a casing having a cylinder "provided with a bore; a head closing one end of said cylinder; a piston in said bore having the end thereofadjacent said head recessed; a iiller member in said recess substantially filling said recess and having a flange adjacent the bottom of said recess providing an annulus between the filler member and the wall of said recess; a spring in said annulus between said ange and head normally urging said piston in a direction away from said head, said head having a cavity confronting said ller member, and said filler member being of-great-er length -thanthe depth of said cavity so that the outer end of said filler member extends into said cavity when `the piston is at the outer end of its stroke; means to conduct'iiuid to and from said cylinder in lcyclically timed relationwith the reciprocation of said ""piston; Lashaft rotatably `mounted in said -ca`sing;.and1;

'8 means establishing a driving connection between said piston and shaft.

4. In a device of the character described, -a housing havin-g a crankcase and a plurality of cylinders disposed radially relative to said crankcase; a head closing the outer end of eachcylinder; a shaft extending throughsaid crankcase and being rotatably supported in said housing; `a piston in-each of said cylinders, each piston having a portion at one yend thereof reduced in diameter to provide a shoulder, said reduced portion having a groove formed therein adjacent said shoulder and having axially spaced, aligned openings extending therethrough in a region between said groove and said one end of said piston; a pin mounted in the openings in the ears of each piston; a roller member mounted on each pin between the ears thereof; a retainer band overlying the outer end of the openings in said-ears and embracing said reduced portion of each piston and having edge portions thereof extending inwardly into said groove to lock the band in place; an eccentric secured to said shaft and engageable by the rollers of the respective pistons, said pistons being free in their -associated cylinders to allow said rollers to make substantially line contact with the outer periphery of said eccentric, each of said pistonsalso having a recess in the outer end thereof; a iiller member in each recess; and `a compression spring in each recess having one end thereof engaged with a head and its other endengaged with a iiller member.

5. In a device of the character described having a cylinder, aV piston andmeans to conduct iiuid to and from said cylinder, said piston comprising: a generally cylindrical'body having a portion at one vend thereof reduced in diameter to provide a shoulder, said reduced portion having a groove formed therein adjacent said shoulder and having axially spaced, aligned openings extending therethrough in -a region between said groove and said one end of said body; a pin mounted in said openings; a member mounted on said pin between said openings; and a retainer -band overlying the outer end of .the openings and embracing said reduced portion and having edge portions thereof extending inwardly into said groove to lock'said band in place.

6. I-n a device of the character described having a cylinder, a piston and means to conduct fluid to and from said cylinder, said piston comprising: a generally cylindrical body having a portion at one end thereof reduced in diameter to provide a shoulder, said reduced portion having a diametrical slot extending thereacross dividing said one end into a pair of spaced ears, said ears having openings disposed substantially perpendicular to said slot; a pin mounted in said openings; a roller mounted on said pin between said ears; and a retaining band surrounding said reduced portion and overlying the outer ends of said openings for retaining said pin in place.

7. In a device of the character described having a cylinder, a piston and-means to conduct uid to and `from said cylinder, said piston comprising: a generally shoulder and also having a diametrical slot extending thereacross and dividing said one end into a pair of spaced ears, said ears having openings disposed substantially perpendicular to said slot; a pin mounted in said openings; aroller mounted onsaid pin; and a band surrounding said reduced portionr and retaining said pin in position, said band having a portion extending into said groove to lock said band in place.

W8. A device as defined in claim 7, in which the band is continuous and the ears have theirl outer edges chamfered to facilitate mounting the band on the reduced portion of the piston.

'9. `In a fdevice of the character described having ga :eylinde'rfaapiston and meansrto conduct uidto and from said cylinder, said piston comprising: a generally cylindrical body having a portion at one end thereof reduced in diameter to provide a shoulder, said reduced portion having a groove formed therein adjacent said shoulder and also have a diametrical slot extending thereacross and dividing said oneY end into a pair of spaced ears, said ears having openings disposed substantially perpendicular to said slot; a pin mounted in said openings; a bushing mounted on said pin between said ears; a roller surrounding said bushing; roller bearings disposed between said bushing and roller; rings at the opposite ends of said roller bearings retaining said roller bearings in place; and a band surrounding said reduced portion and retaining said pin in position, said band having a portion bent into said groove to lock said band in place.

10. In a device of the character described, a valve comprising: a housing having a chamber provided with a ported seat; a rotary valve element in said chamber including a ported disc engaged with said seat, means to conduct uid to and from said valve, a diaphragm overlying one face of said disc, a cover overlying said diaphragm, means securing said cover and diaphragm to said disc, and a plate disposed between said diaphragm and cover, said cover having a diametrically extending slot and having a central opening intersecting said slot, and a shaft extending into said opening and carrying a pin engaged with said slot to provide a driving connection between said shaft and rotary valve element, Whereby said rotary valve element is rendered readily detachable from said shaft and adapted to be rotated through an angle of 180 to reverse operation of the device.

11. In a device of the chanacter described, a valve comprising: a housing having a charnberprovided with a seat, and having ports communicating with said seat; a rotary valve element in saidchamber including a ported disc, one face of said disc engaging said seat, means to conduct uid to and from said valve, and diaphragm means having one side thereof overlying the other face of said disc, a cover overlying said diaphragm and having a diametrical slot extending therethrough and an axial opening also extending therethrough and intersecting said slot; a shaft extending into said opening; a pin carried by said shaft and received in said slot for providing a driving connection between said shaft and cover, said rotary valve element having arcuate inlet and outlet ports disposed on opposite sides of a diametrical line coinciding 'with said slot, whereby said rotary valve can be readily detached from said shaft and rotated through an angle of 180 to reverse the operation of the device.

l2. In a device of the character described, a housing having a plurality of radial cylinders; -a piston in each of said cylinders; a shaft rotatably mounted in said housing; means on said shaft for actuating said pistons, said housing having a chamber for operating uid under pressure provided with a ported seat; conduit means establishing communication between the outer end of each cylinder and la port of said seat; a rotary valve in said chamber including a ported disc engaged with said seat and a cover subject at all times to the pressure of said operating fluid for maintaining said disc seated and having a diametrically extending slot and a central opening intersecting said slot, said shaft extending into said opening from the side of said disc remote from said seat and carrying a pin engaged with said slot to provide a driving connection between said shaft and rotary valve, whereby said rotary valve is rendered readily detachable from said shaft and adapted to be rotated through an angle of 180 to reverse operation of the device.

13. In a device of the character described, a housing having a plurality of radial cylinders; a piston in each of said cylinders; a shaft rotatably mounted in said housing; means on said shaft for actuating said pistons, said housing having a chamber provided with a ported seat; conduit means establishing communication between the outer end afa-45,4517

of each cylinder and a port of said seat; a rotary valve in `said chamber including a ported disc engaged with said seat, means to conduct duid to and from said valve, a diaphragm overlying one face ofrsaid disc, a cover overlying said diaphragm, means securing said cover and diaphragm to said disc, and a plate disposed between said diaphragm and cover, said cover having a diametrically extending slot and having a central opening intersecting l said slot, said shaft extending into said opening and carrying a pin engaged with said slot to provide a driving connection between said shaft and rotary valve, whereby said rotary valve is rendered readily detachable from said shaft and adapted to be rotated through an angle of '180 to reverse operation of the device.

14. In a -device of the character described, a housing having a plurality of radial cylinders; a piston in each of said cylinders; a shaft rotatably mounted in said housing; an eccentric on said shaft and a roller carried by each piston and engaged with said eccentric, said housing having a chamber for operating uid under pressure provided with a ported seat; a conduit means establishing communication between the outer end of each cylinder and a port of said seat; a rotary valve in said chamber including a ported Idisc engaged with said seat, and a cover subject at all times to the pressure of said operating uid for maintaining said disc seated and having a diametrically extending slot and a central opening intersecting said slot; said shaft extending into said opening from the side of said disc remote from said seat and carrying a pin engaged with said slot to provide a driving connection between said shaft and rotary valve, whereby said rotary valve is rendered readily detachable from said shaft and adapted to be rotated through an angle of to reverse operation of the device.

15. In a device of the character described, a housing having a crank case chamber adapted to receive a lubricant and having a plurality of cylinders disposed radially relative to said crank case chamber; a piston in each of said cylinders; a shaft extending through said crank case chamber and being rotatably mounted in said housing; an eccentric on said shaft and a roller carried by each piston and engaged with said eccentric, said housing having a chamber for operating iluid under pressure provided with a ported seat; conduit means establishing communication between the outer end of each cylinder and a port of said seat; a rotary valve in said chamber including a ported disc engaged with said seat, and a cover subject at all times to the pressure of said operating iiuid for maintaining said disc seated and having a diametrically extending slot and a central opening intersecting said slot, said shaft extending into said opening from the side of said disc remote from said seat and carrying a pin engaged with said slot to provide a driving connection between said shaft and rotary valve, whereby said rotary valve is rendered readily detachable from said shaft and adapted to be rotated through an angle of 180 to reverse operation of the device.

References Cited in the le of this patent UNITED STATES PATENTS 688,860 Key et al. Dec. 17, 1901 `1,128,579 Brousseau Feb. 16, 19115 1,277,420 Human Sept. 3, 1918 1,359,321 Brown Nov. 16, 1920 1,920,123 Ernst July 25, 1933 1,979,863 Carruthers Nov. 6, 1934 l1,982,958 Kraus Dec. 4, 1934 1,984,718 Wistrand Dec. 18, 1934 1,995,756 Smith Mar. 26, 1935 2,120,533 Tillson June 14, 1938 2,215,488 Svenson Sept. 24, 1940 2,246,074 Joy lune 17, 1941 (Other references on following page) fll UNITEDSTATES PATENTS `Wellsv Sept. 30, 1941 Ioy Aug. 14, 1945 /Adams Aug. 28, 1945 Anderson `May 20, 1947 Browne Sept. 9, 1947 Griswold Mar. 20, 1951 Delegard Sept. 30,1952 Coberly Dec. 9, 1952 Svenson Apr. Y27, 1954 12 Raymond July 13, 1954 'Heater Mar. 1, 1955 FOREIGN PATENTS Great Britain of V1901 Italy fSept. 18, 1930 Great-.Britain Mar. 20, 1930 Italy Dec. 2, 1947 Great Britain May 17, 1946 Great Britain Sept. 13, 1948