US1212791A - Variable-capacity pump. - Google Patents

Description

C. M. MANLY.

VARIABLE CAPACITY PUMP.' APPLICATION FILED FEB. 4, .1911.

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. 1;.l M. MANLY. 'VARIABLE cAPAcnv PUMP. v

- 'APPLICATION FILED 'PEB.4, 191|. L 1,212,791; y Patented .Im1.16, 1917.'

C. M. MANLY.'

' Patented Jan.16,1917.

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' V'0. M. MANLY.

VARIABLE CAPACITY PUMP.

APPLICATION FILED FEB. 4, 1911.

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, Patented JAH.16,1917.v l amiens-s111514.

I l a 0.1M. MANLY.- vAmABLE CAPACITY PUMP. APPL'ICATION FILED FEB. 4, 19H. v 1,212,791. Patented Jan.16,1917.

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Inventor Mw ,0. M.`MANLY. 1 VARIABLE CAPACITY PUMP. APPLICATION FILED FEB. 4, `IlI'I. L 1,212,791, ,v Patented Ja11.16, 1917.

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Patented Jan. 16, 1917.

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y c. M. MANLY. VARIABLE CAPACITY PUMP.

l l APPLICATION FILED FEB-4,1911- 1,2r1 21,791. Patented Jan. 16,1917.

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Inventor:

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l CHARLES M. MANLY, F BROOKLYN, NEW YORK.

VARIABLE-CAPACITY PUMP.

Specication of Letters Patent.

lPatented Jan. 16, 1917.

Application led February 4, 1911. Serial No. 606,618. v f

' lTo all 'whom it may concern:

Be it known that I, CHARLES M. MANLY, a citizen of the United States, residing at 113 Montague street, Brooklyn, in the county of Kings and State "of New York, have invented a new and useful Variable- Capacit' Pump, of which the following is a speci cation.

My invention relates to variable capacity multiple cylinderV pumps, and more particu-` larly to means for varying the capacltyl thereof and controlling the interaction of the cylinders.

One object of this invention is to provide a multiple cylinder pump in which the fluid circuits of the multiple cylinders are separate from, but capable of interconnecting with, each other.

Another object is to rovide means for varying vthe capacit o the cylinders of said pump, and anot er object is to provide means for utilizing power for operating the capacity varying means.

With these and other objects in view, .my invention consists in the novel combination, construction and arrangement of parts hereinafter described and more particularlyl pointed out in the claims.

In my prior Patents Nos. 710485 and 801097, I have shown multiple cylinder .v pumps with means for varying the capacity of thesaid cylinders, but in these constructions the multiple cylinders have all been interconnected to al common fluid circuit.A

In certain practical applications of these pumps and especially .where they have been employed for generating fluid pressure for operating two or more fluid pressure motors I have found that it would be advantageous to connect up the several cylinders of such a pump to form two or more separate fluid pressure circuits, andalso `to provide means vfor interconnecting and .disconnecting the said fluid pressure circuits to and from each other. Such a pump resemblesin some respects the combination of several separate and distinct pumps,'but asingle pump comprising multiple cylinders so connected as to form multiple fluid pressure circuits may be provided with a single mechanism for varying the capacity of all of the cylinders,

vthus insuring that an exactly equal change` in the capacity of each cylinder-'will occur simultaneously with any change in the capacity of any cylinder. While, therefore, I

prefer to'use, and have illustrated,a pump-y ing mechanism in which a single mechanism 1s used for varying the capacity of the mult1ple cylinders thereof, and thereby the amount of fluidy circulated through the multiple circuits into which the said cylinders are grouped, I do not limit my invention to such a construction, as several variable ca-l pacity pumps may be so` arranged that their mechanisms for varying their capacity are caused to act in .synchronism, without departing from the spirit or scope of my invention. In 'the accompanying drawings, which illustrate one form in which my invention may be carried out, Figure 1 is longitudinal sectional elevation of the pump; Fig. 2 is a cross section on the line4 2-2 Fig. 1; Fig. 3 is across section on the line 3'-3 Fig. l; Fig. 4 is an end elevation looking in the di- `75 rection of the arrow 4 in Fig. l; Fig. 5 is a partial end elevation looking in the direction of the arrow 5 in Fig.- 1; Fig. 6 isa partial top plan view of the left hand end of Fig. 1; Fig. 7 is a developed view of the valves and so their housing which are used to control the mechanism for varying thev capacity of the pump cylinders; Figs. 8, 9and 10 are an elevation partly in section, a topi/plan lview and a cross section 'on the line -10 1O of Fig. v8, of the valve mechanism for controlling the interconnection toand separation from, each other of the multiple circuits of the pump, and Fig. v11 is a diagrammatic plan view, showing the pump adapted to Aoperate two independent hydraulic motors. Fig. 12 is a detail -view of the valve head on an enlarged scale.v

Referring now to the drawings in which the same reference characters relate to the same or corresponding parts in all the'figures, the numeral 20 indicates a crank chamber from which radiate six cylinders 21, 22,

v 23, 24,25 and 26 respectively. Radiating y from the crank chamber 2() are also six valve 10o and 39, the port 38 being connected by4 a 'similar assage, not'shown, to the cylinder 1,10

22. 'Li ewise the valve chamber I 29 has threevpotsfl, 41 and the port 41 being connected by a similar passage, not shown, to the cylinder 23. In the valve chamber 30 are the three ports 43, 44 and 45, the port 44 being connected by the passage 46 to the cylinder 24. rlhe valve chamber 31 has the three similar ports 47, 48 and 49, the port 48 of which is connected by a similar passage, not shown, to the cylinder 25, while the Valve chamber 32 has the three similar ports 490, 50 and 51, the port 50 being connected b a similar passage, not shown, to the cylinder 26. Slidably mounted in the valve chamber 27 is the piston valve 52 comprising the 3 heads, 53, 54 and 55, the head ret 54 being of a width substantially equal to the width of the port 34. Slidably mounted in the 4other valve chambers 28, 29, 30, 31'" and 32 are similar valves 56, 57, 58, 59 and 60 respectively, thevmiddle head of each being substantially equal to the width of thev` middle port of its respective valve chamber. Formed in the right hand face of the valve chamber-27, F igfl, is a passage 61 which connects at its inner end to the port 33, while a similar passage 62 connects at its inner end to the port 35. Similarly the valve chamber 30 is provided with the passages 63 and64, which connect with the ports 43;and 45 respectively. Each of the other Valve chambers is provided with similar passages which connect with their respective outer and inner ports. The outer ports 33, 40 and 47 of the valve chambers 27, 29l and 31 respectively are thus connected by theirprespective passages to the manifold 65 secured to the valve chambers by the screws 66. Similarly the manifold 67 Aconnects together the outer ports 37, 43 and 490 ofthe valve chambers 28, 30 and `32 respectively, while the manifoldl 68 connects together the inner ports 35, 42 and 49 of the valve chambers 27,.

29 and 31 respectively, and the manifold 69 connects together the inner ports 39, 45 and 51 of the valve chambers 28, 30 and 32 respectively.

Formed integral with the manifold 65 is a pipe 70, shown broken in Figs. 1 and 4, and the purpose of which will be later explained. Similarly the manifolds 67, 68 and 69 have formed integral with them the respective pipes 71, 72 and 73. Each of the valves 52, 56, r57, 58, 59 and 60 is provided gudgeon pin 75 connecting thereto a connecting rod 74 which terminates at its inner end in a shoe 76 by means of which it is given a rocking connection through the ring 77 and the retaining rings 78 and 79,

with the valve crank pin 8O on which the said rings are journaled. The valve crank pin 80 .is formed integral with but eccentric to the sleeve 81 journaled in the bearing 82 mounted in the crank chamber 20, the eccentricityof the crank pin 80 being such that in Fig. 1 the center thereof is Vbelow the plane of the paper, whilethe line passing Laisser through the center l'of the said crank pin and ythe center of the `sleeve 81 is perpendicular l to the plane of the paper.

Rotatably mounted lin the sleeve 81 is a vcrank shaft 83 embodying a crank pin 84,

,Mounted on the crank pin 84 is an eccentric bushing 87...with a split bushing88 (formed in two halves) interposed therebetween, the eccentricity ofthe bore of the said eccentric bushing 87 with respect to its outer peripheral surface vbeing equal to the eccentricity of the crank pin 84 with respect to the crank shaft 83.' The eccentric bushing 87 terminates at its left hand end in a spur gear 89 which meshes with the internal gear 90 in which the sleeve 85 terminatesat its right hand end, the difference in diameters of the two said gears being equal to twice the eccentricity of the crank pin 84 with respect to the shaft 83, so that any 'turning of the sleeve 85, with respect to the shaft 83 causes a simultaneous turning of the eccentric bushing 87 with respect to the crank pin 84. It is readily seen that with the parts inthe positions shown in Figs. 1 and 2, the outer -peripheral surface of the eccentric bushing 87 is eccentric with respect to the shaft 834an amount equal to twice the eccentricity of the crank pin 84 with respect to the shaft 83, while if the 'eccentric' bushing be rotated 180 degrees with respect to the'crank pin 84, from its position there shown, the two eccentricities'will counteract each other, thus causing the outer peripheral surface of the said? eccentric bushing 87 to be concentric with the crank shaft 83. Ro-

tatably mounted on the eccentric bushing 87 l is a ring 91 against -which abut the shoes 92 in which the connecting rods 93 terminate. The connecting rods, shoes 92 each cover slightly less than one sixth the peripheral surface of the ring 91, lbeing free to slide circumferentially thereon, and being prevented from lifting therefrom by the retaining rings 94 under which they are free to slide. The upper end of each connecting rod has a roclnng connection through the pin 95 with a piston 96 slidably mounted in each of the cylinders 21 to 26 respectively. Any rotation of the shaft 83 carrying with it the eccentric bushing 87, causes the said pistons to be reciprocated in their respective cylinders, except when the eccentrick In efectingthe variationin 13o the capacity of the cylinders by varying the length of. the stroke of the pistons as above described, it is necessary that the v'alve crank 80 shalll always be at right angles to the real crank arm of the piston crank. The real crank arm isa line drawn from the center of the shaft 83 to the center of the outer peripheral surface of the eccentric bushing 87, and the direction of this line changes at an angular rate, only one half as great as the angular rate at which the eccentric bushing is turned on the crank pin 84,l it is necessary that the eccentric bushing 87 be connected to the sleeve 81 which drives the valve crank pin 80 by some mechanism that rotates the valve crank pin in unison with` the shaft when the eccentric bushing is not being adjusted, and whenI the bushing is adjusted will advance the valve crank pin in synchronism with the real crank arm of the composite crank pin composed of the crank v pin 84 and the bushing 87j. The mechanism shownconsists of a double eccentric piece 97 tted into the right 25 hand end of the eccentric bushing 87 and prevented from turning with respect thereto by the pin. 98, the said double eccentric comprlslng one eccentric 99 concentric with the bushing 87 and a second eccentric 100 concentric with the shaft 83 when the parts are in the positions shown, the two eccentrics being therefore eccentric to each other an amount double the eccentricity of the crank in 84 with respect to the shaft 83. Rotata ly mounted on the eccentric 99 is a square shoe 101 which its in and is free to slide in a vertical slot in the left hand face of the plate103, while the eccentric 100 has rotatably mounted on it a square shoe 102 which fits in, and is free to slide in, a horil zontal slot in the right hand face of' the said plate 103, the two slots in the said plate being thus at right angles to each other and each of a depth equal to one half the thickness of the said plate. The said plate 103 is secured by the rivets 105 to the flange 104 in which the sleeve 81 terminates, the slot in the right hand face of the plate 103 being in line with the line passing throughthe center of the shaft 83 and the center ofthe valve crank pin 80.

In operation, when the bushing is adjusted, the one eccentric 99 is sulicient to properly adjust the valve crank pin in synchronism with the real crank arm of the composite crank' pin. The eccentric 99 is in effect merely al pin at the center of the louter periphery of the eccentric bushing, working in a slot in the disk of the sleeve 81 of the Valve crank pin, radial to the axis of rotation. t is obvious -that the slot, lwhich bears a fixed relation to the crank arm of the valve crankpin must always coincide with the line connecting the supposed pin at the center of the eccentric bushing and the axis of rotation, which line as explained above 'is the real crank arm of the composite crank pin of the pump pistons. When the crank pin 84 and the eccentric bushing are rotating as a unit this connection-acts as a [simple consequently the eccentrics 99 and 100 have no radial movement in their slots. The purpose ofhaving two eccentrics is to pro# vide a driving connection when the eccentric bushing is at its zero position. In this position the eccentric bushing is concentric with the axis of rotation and consequently would merely turn in its slot without driving the sleeve 81. By employing two eccentrics oppositely disposed, one or the other isV always eccentric to thecenter of rotation-to have an effective driving engagement with the disk on the sleeve 8,1. The sleeve'81 is kept in its proper longitudinal position with respect to the Adouble eccentric 97 by the lip 106 on the ring 107 .held in the bore of the sleeve 81 by the pin 108, the said lip 106 projecting into the groove 109 in the said shaft 83.

Mounted on the left hand-end of the crank chamber 20A and secured thereto by the screws 111 is a casing 112 from the left hand end of which projects the -main driving shaft 113 which is journaled in the bushing 114. Formed intermediate the ends .of the shaft 113 is a collar 117 between one side of which and the end of the bushing 114 is a thrust bearing 115, and between the other side of which and the shoulder 116 of the casing is a thrust bearing 119. Formed 1n the right hand portion of the shaft 113 are screw threads 120, while the crank shaft 83 is prolonged to telescope into 'the bore of the said shaft 113 to which it is fastened by the key 121. 1 s

`Mounted on thethreads 120 1s a coactlng nut 122 and surrounding thelnut 122 is a sleeve 123 in which are formed longitudinal slots 124 in which vare slidably mounted the blocks 125. Slidably mounted on the sleeve 123 is a ring 126 provided with-a collar 127 between one side of which and .the half yoke 128 is a thrust bearing 129, and between the other side of which and the otherv half yoke 130 is a thrust bearing 131. Connecting the ring 126, blocks 125 and nut 122 are pins 132. |The right hand end of the slotted sleeve 123 is connected by the pins 133 to the sleeve 85, and the two half yokes 128 and 130 are connected to each other by the screws 134. `If now the yokes be forced to the right, such movement will cause the nut 122 and the sleeve 123, through the blocks 125, to turn in a clockwise direction with respect to the shaft 113, when viewed from' the left hand end of Fig. 1, thus turn- . bearings 129 and 131, the said yokes may be relatively fixed as regards rotation of the shaft 113 and still exert their pushing effect on the nut 122, and thereby adjust the eccentric bushing while it is rotating with the crank shaft 83. The length of the screw 120 and of the slots 124 mayy be made such that with the proper pitch tothe screw threads, the eccentric bushing 87 will be rotated 360 degrees on the crank pin 84 by pushing the nut 122 tothe extreme limit of its motion to the right in Figl.u Since 180 degrees movement of `the eccentric bushing 87I on the crank pin 84, from the position shown, causes the outer peripheral surface of the said eccentric bushing to be concentric with the shaft 83 and thereby reduces the stroke of the pistons to zero, the remaining 180 degrees of possible movement of the said eccentric bushing will carry its center back to the point from which it started or back to maximum stroke. However, while the double eccentric 97 and its coacting parts previously described keep the valve crank pin 80 always at right angles to, or 90 degrees .ahead or behind, the real .crank arm of the eccentric bushingduring the first 180 degrees of movement of the said bushing, yet

at the mathematical point of zero stroke there is no length to the real crank arm and consequently at this mathematical point the angle between it and the valve crank pin disappears. As soon as the eccentric bushing is rotated the minutest amount more than 180 degrees, so as to carry the eccentric bushing out of zero stroke, the angle between the real crank arm and the valve crank pin reappears and is immediately 90 als degrees, but if the valve crank pin was 90 degrees behind the real crank arm during the first 180 degrees of movement of the eccentric bushing, it will be 90 degrees ahead during the second 180 degrees. The result of this is, that if, when the crank shaft 83 was rotated, the valves 52, 56, 57, 58, 59 and 60 moved outwardly in their respective valve chambers while their corresponding pistons in the cylinders 21, 22, 23, 24, 25 and 26 moved inwardly, when the eccentric bushing was in any position of its first 180 degrees of adjustment, the said valves will move inwardly when the pistons move inwardly during all positions of adjustment of the eccentric bushing in its second 180 degreesof adjustment. In the first case the pistons 96 will therefore suck in fluid during their inw ard strokes, from the inner ports of their respective valve chambers, and during their outward strokes will force it out to the outer Laisser ports of the said valve chambers, While in the second case, they will suck in Huid from the outer ports and force it out to the inner ports, thus causing the direction of How of the fluid to -be reversed.

rl`he force necessary to push the yokes 128 and 130 and thereby adjust the stroke of the pump becomes of considerable account in machines of commercial size,'and I there fore utilize power derived from the pump itself to move the said yokes by a fluid pressure adjusting mechanism broadly similar to that shown in my Letters Patent 801096, but here shown in an improvedform which Iy will now describe. Y

Formed integrally with the casing 112,

and parallel to and in the same horizontal lane with the main shaft 113, are two adjusting cylinders 136 Fig. 6 in each of which is mounted a piston 137 suitably fastened to its rod 138, the said rods passingsnugly through suitable bores in the inner ends of said 'cylinders and being prolonged to pass through the ears 139 formed on each side of the yokes 128 and 130, the yokes being secured to the said rods between the collars- 140 and 141 suitably fastened .to the said rods. Closing the outer end of each cylinder is a plug 142 and connected to the space in the cylinders between the pistons 137 andthe plugs 142 are two pipes 143, while connecte tothe space in the said cylinders between the pistons and the inner ends thereof are the two pipes 144. If fluid u-nder pressure is passed through :the pipes 143 into the outer ends of the cylinders 136 it will there act against the ends of the pistons 137 thereby forcing the yokes 128 and 130 to the right and thereby adjusting the length of stroke of the crank of the pump. If fluid under pressure is passedthrough the pipes 144 into the inner ends of the cylinders, it will act against the pistons 137 forcing them to the left, unless they are already at the limit of their motion in this direction, and thereby adjustthe stroke of the said crank in the opposite direction. In order to obtain the fluid pressure for operating the adjusting pistons described, I connect one end of the pipe 145 to one side of one of the main fluid circuits, as through the valve chamber 30, Fig. 1, and the other end of the said pipe I connect to the control valve block 146 mounted in the shell 147 on top of the casing 112, while a similar pipe 148 is similarly connected through the valve chamber 30 to the other side of the same main fluid circuit and to the said valve 'block 146. The pipesf143 and 144 connected to the adjusting cylinders 136 are also connected tol the valve block 146, and by suitable valves and passages in the said valve block 146 which I will later describe,` I control the thereby I utilize power for per orming the v work o -adjusting the stroke o f the pump.

l pin 151 to the lever 152. The 'said lever Connected to one of the collars 141 (Fig.

6) by the pin 149, lis a link 150, the other end of the said link being connected by the extends crosswise in the casing 112 and is connected at its otherend by the pin 153 t'o the link 154, which is connected by the pin 155 tothe rod 156 which is slidably mounted in the said casing 112. Connected to the left hand end of the rod 156, outside of the said casing, by the pin v157 is a link 158 which is alsozconnected by the pin 159 to the lever 160 fulcrumed onthe pin 161 in the bracket-162 extending from the cas` ing 112. The internal or floating lever 15,2 has a rocking connection through the pin 163 with the rod 164 slidably mounted in the bore 165 formed in the upper part of the casing 112, as more clearly see in Fig. 1. The slide rod 164 has formed across its left hand end a T slot 166 which coacts with the groove 167 formed near the right hand end of the valve 168 slidably mounted in the bore 169 of the valve block 146, whereby any longitudinal motion of the saidslide rod 164 will be communicated to the said valve 168, but any side `thrust coming on the lever 152 willbe taken up by the slide rod 164 and thus be preventedv from causing the valve 168, which must be an accurate fit in its bore, to wear itselfor its bore. The lever, links and rods, together lwith the valve and valveblock just described coact to controlV the use of Huid pressure in operating the adjusting pistons 137 wihich4 operate the stroke adjusting mechanism heretofore described. As the said valve block with its valves and passages is rather complicated, I

have shown in Fig. 7 a developed view of it and its valves, to more clearly explain the interaction of the various parts.

Referring now to Fig. 7, the valve 168 shown mounted in the bore 169 of the valve 'block 146, comprises the five heads, 170, 171,

172, 173 and 174 respectively, while the bore 169 has formed in Ait the seven ports 17 5, 176, 177, 178, 179, 180 and 181 respectively. By means of the two pipes 144 (Fig. 6) Athe port 176 (Fig.` 7 is connected to the inner end of both of the adjusting cylinders 136, while the port 1478 is similarly connected by meansof the pipes 143 to the outer end of both of the said cylinders 136. By means, which I will later describe; a supply of fluid pressure is constantly maintained in the port 177. With such luid pressure in the said port 177, any longitudinal motion of the adjusting valve 168, from the position shown, where the heads 171, and. 172 respectively cover the ports 176 and 17 8, causes fluid pressure to be admitted to one or the other of the said ports from which it passes either through the pipes 144 or the pipes 143 into one end or the other of the adjusting cylinders 136 where it acts against the vpistons 137 and forces the yokes 128 and 1,30 to move and thereby 4adjust the pump crank stroke as heretofore described.

The fluid pressure constantly maintained in the port 177 above described is mainly obtained from the main iuid pressure circuits ofthe pump, by the means which I will now describe. The pipes 145 and 148v leading from the outer and inner ports respectively of the valve chamber 30, belonging to one ofthe sets or groups interconnected by the manifolds 67 and 69, are connected to the top of the valve block 146 as already described. l Formed in the valve block 146 just below the pipes 145 and 148 is a bore 189 which is closed at its outer end by the plug 190. Mounted in the left hand end of the plug 190 is a puppet valve 191,v While a second puppet valve 192 is mounted jin the bore 194 in the said valve block in line with and just to the left of the valve 191 and a compression spring 193 is interposed between the heads of the two said valves. Connecting the bore 194 to the pipe 148 is a passage 195 and connecting the bore 189 to the pipe 145 is a similar passagev 196.` Fluid pressure in the pipe 148 is therefore free to pass therefrom, through the passage 195 and, by lifting the valve 192, 'into the passage 197 formed between the passagesl 195 and 196. Similarly fluid pressure from the pipe 145 is free to pass through the passage 196, and, by lifting the valve '191 into the said passage 197. Formed in the valve block 146, below the plane of the paper in Fig. 7 is a passage 198, shown dotted,pone end of said passage 198 being connected to plained, I term the pump valve, and which comprises the two heads 201 and 202 joined by the stem 203. Projecting from, the left,

hand head 202 is a stem 204 and surrounding the stem 204 is a compression spring 205, one end of which abuts against the head the passage 197, while the other end is conj 202, and the other end against the cover plate 206, which closes the enlarged bore I 207 in which the said spring is mounted. Formed in the bore 199 is a counterbored port 208 which is connected by means of the passage 209 with'the port 177 previously de-4 scribed. -Any, fluid pressure passing into the passage 197 from either the pipe 145er the pipe 148 is free to pass through the passage 198 into the end of the bore 199, where:r acting on the end of the valve 200 it will tend to force said valve tothe left. If the said fluid pressure is suicient to spectively of the upper main valve chamber 27, which belongs to the other group of oylinders, lead fluid therefrom to the valve block 146, and if it is desired to be able to use fluid pressure from this group of cylinders for performing the adjustment of the .pump stroke, it may be done by providing the said pipes with passages andcheck valves opening into the passage 197, similar to those just described for the pipes 145 and 148, or the pipes 210 and 211 may be provided with shunt pipes 212 and 213 respectively and check valves 214 and 215 respectively connecting through the pipe 216 with the said passage 197 as shown in Fig. 7. Thus pressure generated in either side of the circuit of either group of cylinders is conducted to the port 177, where under the control of the adjusting Valve 168, it may be utilized for operating the adjusting' pistons as already described. It is readily seen that the fluid pressure in the port 177 will come from whichever pipe has the .highest pressure, and that the check valves will-cut off' communication with the other pipes. At the same time that fluid under pressure is admitted from the port 177 through the port 176 to the inne'r endsy of the adjusting cylinders 136, an equal amount of fluid is forced .out of the outer ends of the said cylinders,

due to the motion of the pistons 137, and such fluid `passes through the port 178 and into the port 179 from whence, as later described, it is led back into the low pressure or suction sides ofthe main fluid circuits of the pump. Similarly fluid pressure admitted from the port 177 through the port -178and'into the outer ends of the adjusting cylinders 136 causes an equal amount to be forced out of the inner ends of said cy'linders through the port 176 and into the vport 175 from whichV it is similarly led into the low pressure sides of the main fluid circuits.

The fluid .exhausted from the adjusting cylinders 136 into the port 176, when the adjusting valve 168 is moved to the left and high pressure is admitted to the opposite ends of the said adjusting cylinders through the port 17 8,- isl free to pass from said port 176 into the' port 175, thence through the passage 217, and into the passage 218 where 1t is free to divide, andpart of it pass through the passage 219, and by lifting the check valve 220, into the passage 196 and Leraren from thence through the .pipe 145 into the main, fluid circuit, if the ,side of the Huid circuit to which the passage 196 is connected is at the time rthe low'pressure side. llf the passage 196 is at the time under high pressure, all of the fluid exhausted into the paspressure side ofthe main fluid circuit of one group of cylinders. The other part of ythe exhausted fluid in the passage 225 is free to pass therefrom through the radial holes 231 in the bushing 232 in the bore 233, and into the axial bore 234 in the said bushing, where it is free to lift either the check Valve 235 and pass into the vpassage 236 and from thence through the pipe 211 into the side of the fluid circuit to which the said pipe is connected, or it will lift the check valve 237 and pass vinto the larger bore 238 in the bushing 232 and pass from thence Athrough radial holes, 239 and into the passage 240 and from thence through the pipe 210 into the side ofthe circuit to which the said pipe is connected.

As explained and shown in my U. S. Letters Patent No. 801097 and in my pending application above referred to, l provide means for collecting and returning to the .main fluid circuits of the pump any fluid leaking therefrom. 4This is especially advantageous Where-the -pump is utilized as the fluid pressure generator of a hydraulic variable speed gear,.where the fluid acted on by the pump is circulated in a closed fluid circuit from the pump to one or more vmotors, and back to the pump and the return to this circuit of fluid leakage as rapidly as it occurs is necessa-ry in order to keep the circuit completely full of fluid, as the maintenance of va full circuit is essential to the proper operation of the hydraulic gear. In such use ofthe pump the fluid is preferably oil, .which serves the double function of transmitting the power and lubricating the working parts and the fluid which leaks from the circuits to the interior of the crank chamber there mingles with the reserve supply into which the rotating parts splash and thus are kept lubricated. 1n the `'aiifesent case the fluid leaking by the pistons and valvescollects in the crank chamber 20 Fig. 1 from w ence it is free to pass through the holes 241 in the bearing bushings 82 and 86 and into the casing 112. Closing the bottom of the said casing is a pan 242 attached thereto by the screws 243, the said pan being divided into two compartments, 245 and 246 respectively, by the vertical wall 244, the

compartment 245 being covered by a wire' net strainer attached to the frame 247 secured by the screws 2,48, whereby all the fluid passing into the compartment 245 will be strained of any solid particles.

Mounted in the casing 112 and secured to the bosses 600 by the screws 249 is a gear pump 250, which for convenience, I term a leakage pump. The said leakage pump embodies a pinion 251 secured to the shaft 252 on the right hand end of which is formed a gear 253 which meshes with the gear 254 formed on theleft hand end of the slotted sleeve 123 heretofore described. Meshing with the pinion 251 is a second pinion 255 secured to the shaft 256, the right hand end of the said gear pump thus formed being closed by the cover 257 in4 which the said shafts 252 and 256 are journaled. Assuming the shaft 113 to be driven by some external source of power ina clock- Wise direction as viewedin Fig. 5, the gear 253 will be driven counter clockwise thereby, and the leakage pump 250 will tend to suck in fluid through a suitable passage, provided in the boss 258 on the right hand similar passage in the boss 259 on the left hand side. Connected tothe boss 258. is a` pipe 260 to which is connected a pipe 261 leading into the side of the compartment '245 in thepan 242. The pipe 260 is continued beyond its junction with the pipe l261 to the housing 147 on top of the casing 112, the said pipe 260 being Athere connected through .the side oftheI valve block 146 (Fig. 7) with the 'y enlarged bore 263 in which the bore 221 previously described terminates. Connected to the boss 259 on the pressure side ofthe leakage pump 250 is a pipe 264, the other end of-which is .conf.

nected through the housing 147 with the valvev block 146, the said connection being made through the ,side of-fthe said valve block by a passage '265 which terminates in the central longitudinal passage 266 inv the valveblock 146 as clearly shownrin Fig. 7. l.

-The right hand end of the passage y266 is connected by .the passage 267 with the bore l 268 which it crosses, the passage-267 terminating in the bor'e 199 previously described.

269cm the left hand e'nd of which is formed a stem 270. Surroundingthe stem 270 and4 mined force.4 Connectingthe enlarged.bore 272 to Ithe passage- 223, shown ldotted in Fig. 7, tovwhichthe bore 221' is also connected asalready" described, is a passage a collar 282.

side thereof andA force it out through a.

Mounted in the bore 268 is a puppet valve.

274, while a second passage 275V connects the said bore 272`also-withthe port 179, the said passage 275 crossing the bore 199 through the counterbored port 276. Formed in the stem 203 of the pump valve 200 is a hole 277 which extends through the stem 204 thereof and connects the enlarged bore 207 with the bore 199 between the heads Mounted between the said collar 282 and the right hand end of the enlarged hole 263 is a compression spring 283, While a similar spring 284 is mounted between the other side of the'said collar and the cover plate 206,- the said springs tending to keepv the said valve 278 in the position shown with the bore 221 closed from communication With the -zenlarged bore 263. Connected to the bore 221 near the valve head 27 9 is a passage which is shown dotted in Fig. 7 and as terminating at its-lower end in the port 180, while connected to the passage 266 is a passage also shown dotted and as terminating in the port 181, the passage 266 -being thus connected to the bore 221' when neither the valve head 173 nor the head 174 covers the port 180 or 181 re-` spectively, the said passages, ports and valve heads thus constituting 4a switch,

which may be opened or closed by movepump lthe liuid pressure generated by it is utilized. as already stated for operating fluid pressure motors andthe fluid exhausted by the said motors is returned to ,the suction side of the pump at the same'rate, except for leakage, as the `motors receive the iluid under pressure from the pump, the fluid thus circulating in a closed circuit from 'the high .pressure side .of the circuit of one group of pump cylinders to a motor and 'back to the low pressure or suction side of the circuit of the same group-of cylinders, and where the pump is usedI for such. purposes I ind it advantageous to maintain a back pressure sub-v stantially higher than atmospheric pressure on the low pressure or suction v side of the circuit of each group yof cylinders, the leakage pump in` such cases serving .a double purpose. Since the leakage pump 250 runs whenever the main driving shaft 113 isl'revolved,1tl1e said leakage pump sucks up the'l reserve fluid' and the leakage collected in vthe compartment 245of the panv 242 and v forces it-through the pipe 264 and the pasf r sage 2 65 `into the passage 266 fromrwhich r it is free to"v pass throughV the interconnect-V ing ports and passages into the passages 219 and 225 and from thence, through the check valves tand pipes already described, into Awhichever sides of the two main circuits are the low pressure Vor suction sides of. the

pump. lf the pressure of the leakage pump rise above the amount necessary to force the head 279 of the low pressure relief valve 278 out of the bore 221l against the action of the spring 284, the excess fluid will pass into the enlarged bore 263 and from thence` will be discharged through the nipe 260 (Fig. 5) back to the suction side of the leak# age pump 250, and such fluid so discharged in passing by the point where the pipe 261 joins the pipe 260 will have an injector effect tending to draw other fluid up from the .pan 242 to the suction side of the said' leakage pump, and thereby reducing the force necessary to drive said leakage pump 250. Of course fluid will blow off through the pipe 260 only when the leakage pump supplies more fluid to the main circuits than is leaking therefrom, but as l find it advantageous in certain applications of this mechanism to make the capacity of' thesleakage pump great enough to always give an oversupply, a reserve supply of fluid is in such cases kept in the pan 242 and the low pressure relief valve is blowing o practically all of the time that the machine is in operation. On this account it is advantageous as regards the efficiency of the machine to arrange the discharge in this manner to reduce the power necessary to run the leakage pump. Also,'the having of the discharge connected to the `suction side of the leakage pump instead of permitting it to blow off into the casing 112 as heretofore, prevents the said discharge from becoming mixed with air and drawn back laterinto the leakage pump in such mixed condition,

as in certain applications of the machine the .stroke is zero, there is no pumping action and therefore there is no high pressure m either side of either circuit. 1n order to supply fluid Ipressure fr adjusting the crank stroke lout of zero, l'provide a reservoir 286 (Fig. 7) and connect the pipe 216, previously described, to the bottom thereof. Slidably mounted in the said reservoir 286- is a free piston 287.1 By means of the valved fitting 288 on top of the said reser-Y voir airis admitted to the upper part of all cases.

the said reservoir when the piston is at the bottom thereof. 1n some uses air under pressure isforced into the upper part of the said reservoir by a hand pump or any suitable means.l With the said reservoir thus 'connected to the ipe 216, any uid pressure in the port 1 7 or the pipe 216,

coming thereto from the main fluid circuits as already explained, acts on the bottom of the piston 287 forcing it upward and compressing the air on the upper side, so that when the crank stroke is brought to zero, there is stored in the said reservoir a volume of fluid under pressure, which being connected to the port 197 and thereby to the port 177 of the adjusting valve, provides fluid pressure for operating the adjusting mechanism to carry the crank stroke out of zero. Owin to the difficulty of preventing air lfrom lea ing past a piston, 1 find it advantageous to cover the upper side of the piston 287 with .a layer of thick oil 300, A

or other more viscous fluid, so that the air is prevented from coming into dlrect con tact with the said piston and leakmg by it .and mixing with the oil in the lower partof the reservoir which flows torand from the main circuits.

As the pressure in the main circuits sometimes fluctuates rapidly, there is at such times a. tendency for the fluid pressure to surge back and forth in the pipe 216, with the result that' the check valves 191, 192, 214 and 215, already described, tend to hammer 'on their sea-ts and thereby not only pound themselves t'o pieces, but also make an obj ectionable noise. 1n order to overcome this, ll provide the said check valve 191 with a small plungeror stem 290 which is slidably mounted in a bore 291 in the plug 190 and so fitted thereto that while fluid can How slowly past the. said plunger into or out of the said bore, yet it prevents `the said plunger from being rapidly reciprocated and thereforeprevents the said check valve 191 from hammerin on its seat.' Similarly ll `provide the chec valve 192 with a plunger fitted to a corresponding bcre in the valve block 146. 1n some applications of my pump I find that a plunger on one end of the check valves does not give sufficient dashpot effectto prevent hammering of the said valvesand 1 have therefore shown'the check valve 214 by which the pipe 210 is lconnectedto the pipe 216, as provldedl with plungers 301 and 302 at each end coperating with suitable bores 303 and 304 inthe valve shell and cap thereof respectively, and I find that this prevents the hammering in The check valve 215 'is similarly provided with plungers at either end coperating with suitable bores.

As it is a very ldifficult `matter-to get the crank out of zero stroke unless there is fluid -pressure available in the port 177 of the '13@ adjusting valve for operating the adjusting mechanism, and as it sometimes happens mounted, is made of such astiffness that the fiuid pressure on the right hand end of it necessary to force the head 201 to the left of the port 208 is sufficiently high to operate the crank stroke adjusting mechanism. If the fluid pressure introduced into the right hand end of the valve bore 199 from the passage 197 is therefore not sufficiently high to operate the said adjusting mechanism it will be unable to force the pump valve 200 sufiiciently to the left to enable it to pass into the port 177. As the valve head 201 is made of a width just equal to the width of the port 208, it is apparent that if the right hand end of the bore 199 is disconnected from the port 17 7, then the said valve head is either just covering the port 208 or the port 177 is connected to the middle portion of the bore 199 and consequently to the passage 266. In either vcase if the operator attempted to perform an adjustment of the crank stroke he would find that his move- .ment of the adjusting valve 168 as previously described could not cause an adjustment to be performed. If, however, he moves the said adjusting valve in either one direction or the other until either the head 17 3 or the head 174 thereof covered the port 180 or the port 181, such closing of either of said po-rts will cut off communication betweenthe passage 266 and the valve bore 221. The leakage pump will therefore be caused to raise its pressure until it is sufficiently high to raise the valve 269 in the bore 268 and thus permit the fluid that blows off by the said valve 269 to pass through the passage 274 and the bore 221 into the passage 218. The spring 273 is made sufficiently stiff' to require that before it can be raised the leakage pump must raise its pressure sufiiciently high to operate the adjusting mechanism,

and such high pressure from the said leakage pump on passing into the bore 199 passes therefrom through the passage 209 into the port 177 where it is available for such use. If the head 201 of the pump valve 200 happens to cover the port 208, the high pressure from the leakage pump on passing into the bore 199, also passes through the hole 277 in the said valve and acting on the left hand end thereof forces the said valve to the right, thus permitting the said high pressure fluid to pass into the port 177. This overcomes any sluggishness or hesitation on the part of the valve 200 when it accidentally rests in a balanced condition coveringthe port 208. It is thus seen that the leakage pump may be called on to furnish high pressure fiuid for operating the crank stroke adjusting mechanism at any time that there is not sufficient pressure obtainable from the main circuits for such purpose. A

As the variation in the len th of stroke of the crank for each degree of angular motion of the eccentric bushing on the 'crank pin is greater the nearer the length of stroke is to zero, and as the length of stroke is exactly zero only when the center of the eccentric bushing is exactly coincident with the center of the crank shaft, it is sometimes difficult for the operator to so adjust the control mechanism as to cause the crank stroke to be brought to zero exactly, even minute movements of the control rod 156 causing the length of stroke of the crank to vary appreciably. In order to enable the operator to easily adjust the stroke to zero and to readily know when it is zero, I provide the control rod 156, as shown in Fig. 6, with a groove or notch 400 which coacts with the pawl or button 401 pressed against the rod by the spring 402, the pawl 401 being slidably mounted in the bore 403 forme-d eccentrically in the plug 404 which is threaded into the eccentric bore 405 in the plug 406 which is in turn threaded into the casing 112. If there is no lost motion in the various joints of the floating lever 152, the yokes 128 and 130, nut 122, thread 120, and other coacting parts by means of which the crank stroke is adjusted and controlled, so that the crank stroke' is exactly the same for definite positions of the control rod 156 no matter whether the rod 156 is being adjusted backward or forward, then the groove 400 is made'to exactly fit the rounded or otherwise shaped end of the pawl 401, and the said groove isI so positioned in the rod 156 that when the pawl is in the groove the crank stroke is exactly zero. It is then both easy for the operator to adjust the stroke to zero and to know when he has effected such adjustment, since the pawl tends to assist the control rod to move after it has started to enter the groove but resists movements of the rod when it is fully into the groove. However, I find it very difficult in practice to avoid a considerable amount of lost motion in the various joints above referred to,

and vconsequently the position of the control control rod of a Width equal to the' pawl lus twice the' lost motion in either direction., The pawl therefore does not act against the side of the groove toI resist movement of the rod in either direction until the rod 13o out raising or lowering its center.

has moved the extra amount necessary to make up for the lost motion in the joints. As it is difficult in manufacturing practice to locate the groove and pawl so' exactly that they will properly locate the exact zero of stroke, I provide the eccentrically bored plugs 404 and 406 above described, and 1t is readily seen thatby turning these two plugs the center of thepawl can be shifted to one .rapidity .with which the operator may adjust the stroke lof the pump, andas in such cases, the operator is likely to exert so much force on his control rod as to bend or injure the 'connection between the floating lever 152 and the control valve 168,1 provide the two lugs 407 and 408 formed in the casing 112 in the' plane of the lever 152 and so posi'- tion these lugs that while they permit the Vlever 152|to be moved suiiiciently to operate the valve, 168, yet they act as stops to prevent the valve from being moved too far and alsobeingin the plane of the lever, any undue stress on it will be taken up on' them and thus prevent any injury to the valve andv its connecting .par-ts. It is furthermore the leakage pump orV its coacting' valves' should -fail to supply fluid pressure to the adjusting mechanism to move the crank i e stroke out of zero, thek operator may move 'his control rod till the iloating lever abuts agains'tfoneiof these lugs 407 and 408 and l thenby manual exertionon .the control rod forcethe nut 122 to one side orv the other and thus ,adjust the stroke out of zero.

1I' have above stated that the middle head vofthe main valves of the pump are made of a width substantially equal to the width on .the middle port of their 'respective valve Vchambers.' vIn Figs.` 1 and 3, -I have shown the main lva'lver52a-s provided with a middle valve head-in the edges ofwhich are formed V notches 306v and 307, and inv practice I make -thef distance from the vpoints of the V -notches v306 in one edget'o the points ofthe v similarly I I rvidey Vnotchesin themiddle V notches 307'in the opposite edge slightly greater than'the width of the port 34, and* head of each ofl thevotherl main valves arranged in -a similar In'anner.- The object Vof `the V notches is to cause the valves to give a more gradual opening and closing of the middle. port, for since the valve crank is either ninety degrees ahead or ninety degrees behind the pump crank, the valves are moving'at their highest velocity just as they are opening or closing the middle port of the valve chamber and the piston at this same instant is moving slowest since it is at'either its outer or its inner dead center, and if-at its inner dead center it is instantaneously changing from a condition of sucking fluidk into its cylinder tol a condition of forcing it out..` If the valve abruptly change the middle port connection from where it is letting low .pressure fluid be sucked into the cylinder, to 'where the cylinder is connected to the high pressure side of the main fluid circuit, before-'the piston has moved far enough on its outward stroke to really begin to force fluid fromfits cylinder, the high pressure or their equivalents, is readily seen when it 1s noted that; with the valve stroke and piston stroke as here shown, the valve opens about twenty times as fast as lthe piston moves when the piston crank isA at full stroke v and is moving through the first three degrecs of its travel ,from either. dead center, whereas the total movement of the valve is onlyabout one half as great as the total movement of the piston. As they stroke of a the piston crank is decreased, the opening seen that if the crank stroke 1s at 'zero-and 40 v amount of powery absorbed by the pump, the

pressure of the iuid will be increased exactly as the crank stroke is decreased, the difference between the pressure ofthe vfluid 1n the cylinder when'the piston issl'lcking in and vwhen it'is forcing fluid out becomes greater and this difference makes the ab` v ru'ptness` of openingxof the valve worse and By 'providing` the head of the valves with V notches and properlywproportioning kthem as to number, length, "breadth and depthy I have been able to make pumps work ilo without appreciable .noise at speeds vof over' v twelve hundred revolutions per minutepand pressures of over two thousand pounds. I have also found it advantageous, where the middle port is utilized to control the flow of fluid and'where the valve coperating 4therewith is consequently provided with a middle or controlling head, 'to make the width of 4the valve head between the V notches inits opposite edges slightlv wider than the port,

so that the piston will have actually begun to compress the fluid-.inthe cylinder before i valve bodies 353 and 354 respectively.' 55

the valve opens, thereby tending to make the pressure in the cylinder nearer equal to that in the high pressure circuit when the valve connects it to the cylinder. Where the outer and inner ports are utilized to control the flow of fluid, the valve has no middle head,y

but the other heads are made longer and the V notches are then made in the inner edges of each head, and the distance between the points of the V notches is made slightly less than the distance from the inner edge of one port to the inner edge of the other. I also find it advantageous to so space the V notches in each edge of the valve that the edge becomes a series of sharp points, so that there is at no period of the stroke of the valve any abrupt change in the space between the valve edge and the edge of the port through which the fluid is flowing, thereby obviating any abrupt changes in the velocity of flow of the fluid. It is readily seen that by properly proportioning the .V notches the area of port opening for the passage of the fluid to and from the cylinder can be made to change in any d ired relation to the change in velocity of the piston in its stroke, and I find in practice thatgood results are obtained where thel V notches are so proportioned that the area of port opening varies in substantially the same manner as the velocity of the piston, the velocity rof flow of the fluid through the port,opening thus varying in synchronism with the velocity imparted to the fluid by the piston movement, or as the sine of the angle of the crank.

Referring again nowto Figs. 1 and 4 where the pipes 70, 72 and 71, 73 leading from the manifolds 65, 68 and 67, 69 respectively by which the cylinders are arrangedin two groups of three each, are shown broken; where it is desired to provide means for interconnecting thel two groups of cylinders either at the will of the operator or automatically by some coacting mechanism, before leading 'the said pipes to the' mechanisms to which the fluid pressure is to be delivered, I interi, ose in the said circuits the control valve shown in Figs. 8, 9 and 10.- This control valve comprises a main Shell 350 in which are formed the two i symmetrically# arranged chambers 351 and 352, in which are rotatably mounted the Formed in the chamber 351 at the lower level are the three equidistant ports 355, 356 and 357. At the same level in the chamber 352 are the three ports 358, 359 and 360,

the port 356 of the chamber 351 being con- V nected to the port 359 of the chamber 352' fold 68. Similarly the port 358` is connect- I height is a blind port 364, while diametrically opposite the 1)ort 356 is a similar blind port`365. In the chamber 352 are similar blind ports 366 and 367 At a higher level in the chambers 351 and 352 there are similar sets of ports 368, 369, 370, 371, 372 and 373, 374, 375, 376 377 shown dotted in Fig. 9 and some of them in section in Figs. 8 and 10, the ports 369 and 374 being connected bv the passage 378, while connected to the ports 368 and 373 are the pipes 70 and 71 respectivelv leading from the manifolds 65 and 67 respectively of Fig. 4. Connected to the ports 370 and 375 are the pipes `37 9 and 380. The valve body 353 comprises a top 381 on which is formed a gear 382, while depending from the lower face of the said top 381 are the four lobes 383, 384, 385 and 386, the outer peripheral surfaces of whlch fit snugly against the inner surface of the chamber 351, the said lobes being joined together at the bottom of the said chamber by a plate 387 which also lits the bore of the said chamber. tegrally with the said lobes is a mid plate 388 which also fits the bore of the chamber 351 and thus divides it into an upper and a lower compartment. All of the ports in the chamber 351 are madeof an equal size and the four said lobes are made of a width equal to that of the ports, while the lobe 383 is arranged diametrically opposite to the lobe 385, and the lobe 384 is diametrically opposite the lobe 386. The valve body 354 in the chamber- 352 comprises a top plate 390, gear 391,

Formed infour lobes, 392, 393, 394 and 395, a bottom plate 396 and a mid plate 397, similar in all respects to the corresponding parts of the valve body 35.3. Formed on the valvel body 353 is a stem 398 on which is mounted a crank handle 399 by` means of which the valve bo'dv 353, and through the ir termeshthrough its respective compartment to the pipes 37 9, 380, 362 or 363 respectively, but

the lobes which cover the passages 361 and 378 prevent communication between the fluid in the two chambers, whilethe mid plates prevent communication between the upper and lower compartments of their respective chambers. The diametrically opposite arrangement of the lobes and ports as above described makes the valve bodies balancedl against the pressure of the fluid passing through them.

In Fig. 11 of the drawing the pump is shown as adapted to operate two independent hydraulic motors 450 and 451, The mo-l tors, which may be of any desired type, are

provided with outer ports for receiving the fluid under pressure and inner ports through which the fluid is returned to the pump. 'As shown, the pipe 379 delivers fluid under pressure from the upper compartment of the chamber 351 of the control valve 350 to the outer port .of the motor 450 and vthel pipe 362 returns `the iuid from the inner port of the motor to the lower compartment external power in a clockwise direction.I .when viewed from the left hand end of Fig. 1, the pipe 362 is connected to a source of fluid supply and leads fluid therefrom `through the lower compartment of the chamber 351 of the circuit control valve 350 4and from thence by the pipe 72 to the manifold 68 connected to the inner ports of the valve chambers'27, 29 and 31, while the pipe 379. delivers fluid pressurefrom theI upper compartment of the said chamber of the control valve 350 to some receptacle or mechanism requiring fluid pressure -to be delivered to it, such fluid pressure being brought into said control valve from the outer ports of the valve chambers 27; 29 andl 31 through the manifold'65 and pipe 70. Similarly the pipe 363 fromthe lower compartmentl of the chamber 352 of the control valve 350 leads fluid, from the same `or a second source of supply, through the pipe 73 and the manifold 69 to the inner ports of the valve chambers 28, 30 and 32,

while the pipe 380 leads fluid under pressure ,from the upper compartment of ,the

said -control valve chamber to a second receptacle or mechanism, said fluid pressure -being delivered to said upper compartment .from the outer ports of said valve chambers 28, 301and 32 by the manifold 67 and pipe 71. Since all the pistons have a common y crank pin that actuates them, they all must at all times have equal strokes, and if all .of the cylinders are of the same. diameter all must furnish equal amounts of `fluid under vpressure to the manifold 'to which their respective valve chambers are connected and 1 must all receive equal amounts of fluid from u theV other manifold belonging to the same group. If for any reason a higher Huid pressure is desired or obtained in the presi sure side of the manifold of one group than in the pressure side of the manifold of the other group, such dierence in ressure in the two groups will in no way a ect the operation of the pump. If for any reason it is desired to deliver more fluid to one receptacle or driven mechanism than,A to the other, the operator can, by moving the control val've handle 399, swing either the lobe 385 around to partly close the port 357 or -the lobe394 to partly close the port 360, in leither case as the lobe closes the delivery rection' it will completely shut oil the delivery port of one or the other of the control valve chambers and cause all the Huid from this chamber to be delivered to the other chamber along with an equal amount already delivered to and through this latter chamber. By means of the blind ports, above described, in the valve chambers, the lobes which are in front ofthe said blind ports4 are. caused to have the same variation in radial pressure as the diametri'eally opposite lobes which coact with the delivery and bypass ports, and consequently the, control valveremains.l perfectly balanced in all positions. Similarly if the directionof flow of the fluid inthe-control valve is reversed by carrying the pump stroke through zero, the lobes of the control valve coacting' with the ports in the upper compartments of the chambers of said control valve cause a similar diverting of the fluid pressure delivery from one chamber tothe other by similar movements of the control valve handle. At the same time thatv the 'fluid pressure delivery is diverted by movement ofthe control handle, the fluid supply through the control valve is similarl affected since the same amount of throttlmg occurs simultaneou'sly in both compartments' of eitherv chamber of the control valve.

When the pump'is connected 'to two separate motors in the mannershown in Fig. .11,

the control valve 350 may be operated to produce any desired relative speeds of the two motors or t-o stop either motor independently of the other. When the control 'handle 399 is in the position shown in Figs. and 11 `with the pumpcircuits disconnected the moi tors 450 and 451 willreceive equal .volumes/ of Avfluid under pressure from the pump and, lif the motors are identical, will bel driven at

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