US2442058A - Remote control hydraulic apparatus - Google Patents

Description

May 25, 1948. H. E. PAGE 2,442,058

I 7 REMOTE CONTROL HYDRAULIC APPARATUS 1119a Dec. 26, 1 945 4 Sheets-Sheet 1 IMWTEMII Ma May 25, 1948. H. E. PAGE REMOTE CONTROL HYDRAULIC APPARATUS Filed Dec. 26, 1945 4 Sheets-Sheet 2 m WH Rm :2 3 32 L Jnv 15117101 Jianbart E.

May 25, 1948. H. E. PAGE REMOTE common HYDRAULIC APPARATUS Filed Dec. 26, 1945 4 Shuts-Sheet 5 Patented May 25, 1948 REMOTE CONTROL HYDRAULIC APPARATUS Herbert E. Page, Dayton, Ohio Application December 26, 1945, Serial No. 637,278

' Claims.

My present invention relates to a remote control hydraulic apparatus, and more particularly to an apparatus for delivering hydraulic fluid with a pressure and volume output which will vary in accordance with predetermined load conditions.

An object of the invention is to make an improved and simplified remote control hydraulic apparatus.

Another object is to make a hydraulic apparatus having an initial high capacity output and a secondary lower capacity higher pressure output.

A further object is to make a hydraulic apparatus havin adjustable controls for increasing automatically the hydraulic pressure applied upon a predetermined increase in the load.

A still further object is to make a plural actuating hydraulic apparatus adapted for an initial high volume, low pressure delivery under light load, and changing automatically to a predetermined high pressure, low volume delivery upon the imposition of a predetermined load.

In order to attain these objects, and others which will be apparent from a perusal of the fol lowing description and the accompanying drawings, I provide in accordance with one feature of the invention an apparatus having a plurality of cylinders of selected sizes, which are disposed at different distances from a fulcrum. Pistons are mounted to operate in the cylinders, through lever arms which may have a common fulcrum, to deliver different volumes of fluid at predetermined pressures in each. By means of simple controls the volume and pressure output of liquid by the device may be varied as required to meet predetermined or encountered load conditions.

These and other features of the invention will be apparent from the following description and the accompanying drawings, in which:

Figs. 1, 2 and 3 are respectively plan, side and end elevations of a hydraulic apparatus embodying the present invention;

Fig. 4 is a longitudinal vertical section taken on the line 4-4 of Fig. 1;

Fig. 5 is a transverse vertical section taken on the offset line 55 of Fig. 4;

. Fig. 6 is a fragmentary transverse horizontal section taken on the line 6-45 of Fig. 5;

Fig. '7 is a vertical longitudinal sectional view through a block incorporating the principal actuating parts of the apparatus taken on the line 11 of Fig. 5; I

Fig. 8 is a similar view taken on the line 8-8 of Fig. 5; and

Fig. 9 is a horizontal transverse sectional view 2 through the same block taken on the line 99 of Fig. 5.

Referring to the drawings in detail, which illustrate a preferred embodiment of my invention, a casing i 0 of sheet metal or other suitable material has a cylinder block H mounted within an end thereof. A liquid reservoir or storage cylinder l2 has one end thereof sealed'in an annular recess i3 in the block H. The other end of the reservoir is sealed in a recess H in an end plate l5. A bolt ii having a sealing gasket is under the head thereof, passes through the end plate and is screwed into a threaded opening in the block to draw the reservoir cylinder parts together into liquid-tight sealed relation. A second liquid reservoir IQ is mounted above the reservoir i2 and feeds liquid by gravity into the lower reservoir through a passage 20 interconnecting the two reservoirs. A filler pipe 2| extends upwardly from the upper reservoir [9 to a point just below the level of the casing l0, and a filler cap 22 is secured in an opening in the casing over the filler pipe M.

A pair of bearing supports 24 and 25 project upwardly from the forward or discharge end of the block I i and in them a fulcrum shaft 26 is mounted for pivotal movement. An end portion 21 of the shaft 26 projects outwardly through an opening in a side of the casing It. An operating handle lever 2a is keyed to the projecting end portion 21 of the shaft 26, and a piston operating lever 29 is keyed to the shaft 26 between the bearing supports 24 and 25.

. A pivot pin 32 is mounted in an opening drilled transversely through the piston operating lever 29 to have a press fit in the opening with both ends of the pin projecting out from the sides of the lever. A pair of piston connecting links 30 and 3! are mounted with their upper ends pivoted one on each of the projecting ends of the pivot pin 32. The lower end of each of the piston connecting links 30 and 3! is divided, as shown in Fig. 5, and is connected pivotally to an upright projection 33 on the upper end of each of a pair of pistons 34 and 35, respectively.

The piston 35 is illustrated as being larger in diameter than the piston 34, it being apparent, however, that the diameters of the pistons may be varied at will, and should be predetermined prior to manufacture so as to produce the pressures desired in the operation of the apparatus.

The pistons 34 and35 are mounted in cylinders 31 and 38 machined in the block II. The walls of all the cylinders and pistons are finished in accordance with good current practice, such as it to seal the passage.

by guiding, lapping, honing, or otherwise to produce a desired degree of smoothness and regularity.- Each cylinder has an annular ring groove 39 in which is mounted a sealing ring 40 preferably or resilientv synthetic material.

A third piston connecting link 4| is pivoted in a notch 42 in the outer end of the piston operating lever 29, the lower end or the link 4! being connected to a third piston 43. This third piston is generally similar to the other two, but is considerably longer and, as here illustrated, larger in diameter than either of the other two pistons, The piston 43 is mounted in a cylinder 44 machined in the block I I similarly to the other two cylinders 81 and 38. The piston 43 also is provided with a sealing ring '45 mounted in an annular groove therein.

Fluid passages are provided in the block from the reservoir l2 to the cylinders, the flow of fluid therethrough being controlled by valves and other mechanisms in the following manner:

A main inlet passage 41 opens into a lower portion of the lower reservoir i2 and extends for: wardly to the plane of the lower portion of the ofiset sectional plane of Fig. 5, as indicated by the line 5-5 of Fig. 2. At this plane the passage opens into a laterally drilled passage 48, the exposed end 49 of which is plugged. From this lateral passage 48 two passages 50 and El extend upwardly, in rear of the high pressure cyl-v inders 31 and 38 respectively. Since both of these upwardly extending passages are similarly constructed, only the right hand one 50 as shown in Fig. 5 will be described in detail. This passage also is shown sectionally in Figs. 4 and 7,

The upper portion of each of the passages 5.0

is enlarged as at 52 and is further enlarged as at 53. A seat for a ball check valve is provided at each of these two enlargements of the passages, and ball check valves 54 and 55 are mountedon the seats thus provided. The enlarged upper end 53 of each passage is threaded, as shown in Fig. 7, and a plug 51 is screwed into Horizontal passages 58 and 59 connect the first enlarged portions 52 of the passages 50 and 5| into the lower ends of the cylinders 31 and 38, respectively. The forward ends of both of the horizontal passages 58 and 59 are plugged as at 60, see Fig. 7.

A cylindrical cam chamber BI is drilled transversely of the block H with its axis passing through the axes of the vertical passages 50 and A cam 62 is inserted in the cam chamber 61, and has enlarged cylindrical end portions 83 and 64 thereof journalled in the cam chamber outwardly beyond the vertical passages 50 and 5|. A sealing ring 65 is mounted in a groove near the outer end of the cam 62, and a snap retaining ring 6'! is inserted in an annular groove in the wall of the cam chamber to overlie the outer end of the cam to secure it in position.

A cam operating handle 68 is mounted on a projecting stem portion 59 of the cam, and is secured thereto as by a pin iii. A spring pressed ball H inserted in a recess 12 of reduced diameter in the base of the cam chamber 6| exerts a resilient outward positioning force on the cam to hold it against the snap retaining ring 61.

A pair of cam lobes .13 and 14 are provided on the cam 62, one lobe being positioned in alignment with each 01. the passages 50 and BI, respectively. The cam lobes .are of a height to provide suiilcient clearance inwardly from the wall of the cam chamber to permit a free flow of liquid upwardly through the passages 58 and 4 6| at all times. A pin 15 of aslze and shape to permit hydraulic liquid to flow betweenit and the wall 01 the passage in which it is. mounted, is inserted in each or the passages 50 and-ll. These pins are of a length normally to permit the lower ball checks 54 to seat, but to raise the balls l of! their seats when the pins 75 are raised by their respective cam lobes. and 14 are arranged in partially overlapping and partially angularly offset relation, as shown in Fig. 1. In this manner either onepin or the other or both may be raised by rotating the cam to bring the desired'cam lobe or lobes into operating position. By turning the cam to move both cam lobes out of contact with both plus, it is apparent that both of the lower ball checks will be free to seat.

A lateral passage 71 shown in Figs. 4, 7, 8 and 9 connects the enlarged upper portions 53 or the 7 vertical passages 50 and ill to each other. This lateral connecting passage 11 in turn opens into the main fluid discharge passage 18 opening out of the forward end of the block II. A fitting 19 may be threaded into the forward end of this passage to connect the apparatus to a mechanism (not shown) to be supplied with the hydraulic fluid.

The above-described passages and associated parts comprise essentially the fluid intake, compression, control and discharge of the high pressure, low volume, side of the hydraulic apparatus embodying the present invention.

Referring now to the passages associated with the low pressure, hi h volume cylinder 44 and its piston 43, a cylindrical valve chamber 80 'is drilled upwardly from the bottom of the block I i, as shown in Figs. 4. 7 and 9. This valve chamber 80 has an enlarged threaded lower end portion 8|, From the upper end of the valve chamber 80, a passage 82 of reduced diameter opens upward, and at the upper end of this reduced passage the passage is enlarged as at 83 to provide a valve seat for an inlet ball check valve 84.

A seat for a second, or outlet ball check valve 81 is formed between the upper end of the first enlarged passage 83 and a further enlarged passage 85. The upper end of the passage 85 is plugged as at 88. r

A lateral passage 16 (see Figs, 7, 8 and 9) opens into the first enlarged passage 83, between the upper and lower ball checks, and this lateral passage also opens into a vertical passage 86 which in turn opens into the main intake passage 41 from the reservoir l2.

A valve piston 89 is mounted slidably in the valve chamber 88, and a hydraulic sealing ring .mounted in a groove in the piston 89. A stem 8| projects upwardly from the valve piston 88 and is surrounded by a biasing coil compression spring 92 which is held in compression between the upper end of the-valve chamber and the top of the valve piston 89, The upper portion 98 of the stem Si is further reduced in diameter and is shaped to permit free flow of hydraulic liquid between it and the wall 01' the reduced passage 82 above the valve chamber in which it is inserted. The length of this reduced stem portion 93 is such as to raise the lower or inlet ball check 84 off its seat upon a predetermined upward movement of the valve piston 89, and to permit the ball to reseat upon a predetermined return movement downward of the piston.

An axial opening 94 is drilled in the lower end of thepiston 89 to receive a stem 95 which ex= The cam lobes I3 tends upwardly from a combined sealing and valve pressure adjusting plug 91. A coil spring 98 surrounds the plug stem 95 and is heldin compression between the bottom of the piston 89 and the top of the plug 91. The plug 91 is threaded into the enlarged lower end 8i of the valve chamber 80. The plug 91 maybe adjusted axially by screwing it in or out as required to vary the force opposing the biasing action of the coil spring 92. A hydraulic sealing ring 98 is mounted in a groove in the plug 91.

From the first enlarged passage 83 between the ball checks 84 and 81 a passage I opens into the lower end of. the large cylinder 44. A low pressure discharge passage IOI connects the upper enlarged passage 85 above the upper ball 81 to [the transverse passage 11 which in turn opens into the main hydraulic discharge passage 10. v

In order to connect the main discharge passage 18 with the valve chamber 00 below the valve piston 89, a vertical passage I02 vextends downwardly from the main discharge passage 18 to a lateral passage 96., The passage 96 opens into a horizontal passage I03 which in turn opens into the valve chamber 80. See Figs. 4, 7, 8 and 9.

To permit the release of pressurized liquid from the main discharge passage 18, a hydraulic re-- lease needle valve I04 is provided. The valve'i04 is threaded into a valve chamber I05 whichopens into a co-axial passage I06 of smaller diameter than the valve chamber. A seat I01 for the needle valve I04 is provided at the offset between the valve chamber and the passage I06. The passage I06 opens into the vertical pass-age I02,

which in turn opens into the main discharge passage 18. From the needle valve chamber I05 a horizontal passage I09 extends rearwardly and opens into the reservoir I2. Thus, upon opening the release valve I04 fluid is permitted to flow from the high pressure discharge passage 10 through the passages I08 and I00, through the valve chamber I05 and thence through the passage I09 back into the storage reservoir I2.

In describing the operation of the apparatus, let us assume that the discharge passage 18 is connected to a, piece of hydraulic equipment such as a hydraulic press, not shown. In the use of such presses it is usually desirable to have the ram thereof move some distance before encountering the main work load to be imposed on it.

The loads which may be handled, of course, will vary with changes in the sizes of the three cylinders 31, 08 and 44, and the relative length of the handle 28 and that of the lever arms through which the pistons are operated. These values,- oi. course, can be calculated readily and it is believed to be unnecessary to set them forth for any specific application.

Assuming that the apparatus is ready to be operatedunder a progressively increasing load, the adjusting plug 91 may be screwed in or out as desired to an adjusted position substantially as indicated in Figs. 4 and '7, so that the lower valve spring 99partly compensates for the biasing action of the upper valve spring 92, but so that the reduced upper portion 93 of the stem Si is not in contact with the lower ball check 84. The cam 82 may be turned manually to move both of the cam lobes 13 and 14 out of register with theball operating pins 15 or into registry with either one, or both of said pins as required. The relief valve I04 is closed. 7

The free end of the handle 28 then is moved reciprocally up and down to move the lever 29,

a larger quantity of hydraulic fluid than the latter. The third cylinder 44 not only is of larger diameter than either of the other two, but also it is pivoted at a greater distance from the fulcrum shaft 26, so that it will have a longer stroke than the other two cylinders. It therefore has a larger displacement than either of the other two cylinders.

Assuming for the purpose of illustration that the cam lobes 19 and 14 are out of registry with their pins 15, initially all of the lower ball checks 54 and 84 will be positioned on their seats. On an upward stroke of the operating handle 28 the free end of the lever 29 will rise, thereby raising all three pistons. This action, of course, reduces the pressure in the cylinders and permits the hydraulic liquid from the reservoir, under atmospheric pressure, to flow into all three cylinders through the intake passages previously described. On reaching the top of the handle stroke the atmospheric pressure from the reservoir is balanced by the stopping of the pistons and the lower ball checks 54 and 84 return to their seats by gravity.

On a downward stroke of the handle 28 the lever arm 29 forces the three pistons downwardly in their respective cylinders, therebyincreasing the pressure on the liquid in each. This increase inpressure is transmitted to'the passages between the upper and lower ball checks of each cylinder, and tends to force the lower ball checks in each instance onto their seats and to raise the upper ball checks from their seats. The upper ball checks will be raised from their seats as soon as the pressure below the ball checks increasesbeyond the pressure in the discharge passages above them.

Since the passages I02, and I03 connect the discharge passage 18 to the valve chamber 00 between the piston 89 and the plug 91, the discharge pressure thus is transmitted to the lowerflow of liquid back and forth through the inlet passages past the open lower ball check 84.

As it is assumed, for the present illustration, that both the cam lobes 13 and 14 are out of registry with their pins,15, continued operation of the handle after the largest cylinder 44 has thus been made inoperative will be at a much greater mechanical advantage then before. The output then will be entirely by the two smaller cylinders 31 and 38', with their pistons operating through a shorter lever arm than the largest piston.

If thereafter the load increases to a point where it is beyond the capacity of both of the two smaller cylinders 31 and 38, either one or the other of these two cylinders can be made inoperative by turning the cam handle 61 to bring either of the cam lobes 13 or 14 into engagement with the pin 15 of the cylinder it isdesired to make inoperative. This raises the lower ball check 54 of the selected cylinder and prevents further pumping action by that cylinder. The upper ball check 55 of the inoperative cylinder holds the both inlet ball checks 56 from their seats. When this is done, upon the pressure in the discharge passage rising sufiiciently to move the valve piston 89 upwardly to lift the lower ball check 86 from its seat, all three cylinders will thereupon be inoperative. The pressure will be held at this point until pumping is contlnuedwith either the cylinder 3] or 38, or both, made operative by turning the cam handle 88 to move the cam lobe controlling the selected cylinder out of contact with the pin controlling the ball check for that cylinder.

After a working stroke of the operated mechanism has been completed, the pressure in the delivery zone can be released byturnlng the needle valve I (it to open it. Upon opening the needle valve, the pressurized liquid is free to flow from the main discharge passage 18 back into the reservoir i2,

While I have illustrated and described a preferred form of my invention, it will be clear to those familiar with the art that modifications can be made without departing fromthe spirit of the invention. Therefore, it is not desired to limit the invention except as specifically defined in the appended claims.

I claim:

L'A hydraulic apparatus comprising, in combination, a high pressure cylinder, a low pressure cylinder, common outlet means connected to both cylinders, separate inlet means for each cylinder, a piston operatively mounted in each cylinder, a biased pressure operated valve operatively controlling the low pressure cylinder,

and a pressure transmitting connection between the common outlet and the pressure operated biased valve to transmit pressure from the common outlet to the valve in a direction opposed to the bias of the valve to move the biased valve on the attainment of a predetermined pressure in the common outlet to inactivate thev low pressure cylinder.

2. A hydraulic apparatus comprising, in combination, a high pressure cylinder, 9. low pressure cylinder, common outlet means connected to both cylinders, separate inlet meansfor each cylinder, a piston operatively mounted in each cylinder, a

check valve operatively mounted between thecommon outlet and each cylinder, a check valve operatively mounted in the inlet to each cylinder, a biased pressure operated valve control member operatively controlling the inlet to the low pressure cylinder, and a pressure transmitting connection between the common outlet and the pressure operated biased valve to transmit pressure from the common outlet to the valve in a direction opposed to the bias of the valve to move the biased valve on the attainment of a predetermined pressure in the common outlet to inactivate the low pressure cylinder.

3. A hydraulic apparatus comprising, in combination, a high pressure cylinder, a low pressure cylinder, common outlet means connected to both cylinders, separate inlet means for each cylinder, a piston operatively mounted in each cylinder, a checis valve operatively mounted between the common outlet and each cylindena check valve operatively mounted in the inlet to each cylinder, a biased pressure operated valve control member comprising a cylindrical housing, a floating piston operatively mounted in the housing, spring biasing means mounted to act on one side of said p ston, adjustable spring counterbalancing means mounted to operate on the other side of said piston, and a pressure transmitting connection between the common outlet and the pressure operated biased valve to transmit pressure from the common outlet to the valve in a direction opposed to the bias of the valve to move the biased valve on the attainment of a predetermined pressure in the common outlet to inactivate one of said cylinders.

4. A hydraulic apparatus comprising, in combination, a plurality of high pressure cylinders, a low pressure cylinder, common outlet means connected to both cylinders, separate inlet means for each cylinder, a piston operatively mounted in each cylinder, cam means selectively controlling the inlet to each high pressure cylinder, a biased pressure operated valve operatively controlling the inlet to the low pressure cylinder, and a pressure transmitting connection between the common outlet and the pressure operated biased valve to transmit pressure from the common outlet to the valve in a direction opposed to the bias of the valve to move the biased valve on the attainment of a predetermined pressure in the common outlet to inactivate one of said cylinders,

5. A hydraulic apparatus comprising, in combination, a cylinder block having a fulcrumed handle, a high pressure cylinder and a low pressure cylinder in said cylinder block, a piston operatively mounted in each cylinder, means operatively.

connecting the pistons to the fulcrumed handle, common outlet means connected to both cylinders, separate inlet means for each cylinder, a check valve associated with each cylinder normally to prevent return flow of liquid from the cylinder toward its inlet, a secondary check valve operatively mounted between each cylinder and a common outlet normally to prevent flow of liquid from the outlet toward the cylinder, a spring biased pressure actuated member associated with one of said inlet valves, and a, pressure transmitting connection between the common outlet and the pressure operated biased member to transmit pressure from the common outlet to the biased member in a direction opposed to the bias of the I biased member to move the biased member relatively to one of said inlet check valves on the attainment of a predetermined pressure in the common outlet to unseat said inlet check valve.

6. A hydraulic apparatus comprising, in combination, a cylinder block having a plurality of cylinders formed therein, an operating handle fulcrumed on the cylinder block, a piston operatively mounted in each cylinder, means operatively connecting the pistons to the handle, a liquid reservoir, a separate inlet passage from the reservoir into each cylinder, an inlet check valve between each cylinder and the reservoir, a common outlet ior both cylinders, an outlet check valve betweenthe common outlet and each cylinder, a biased valve control member normally out of restrictive relation with the inlet check valves. pressure operated means mounted to oppose the'bias of the valve control member. and pressure transmitting means operatively connecting the common outlet and the pressure operated means, to operate the pressure operated means on a predetermined increase in outlet pressure, thereby to move the separate inlet passage from the reservoir into nected to the common outlet and to the side of each cylinder, an inlet check valve between each cylinder and the reservoir, 9, common outlet for both cylinders, an outlet check valve between the common outlet and each cylinder, a biased valve control member normally out of restrictive relation with the inlet check valves, pressure operated means mounted to oppose the bias of the valve control member, and pressure transmitting means operatively connecting the common outlet and the pressure operated means, to operate the pressure operated means on a predetermined increase in outlet pressure, thereby to move the biased valve control member into valve opening relation to one of the inlet check valves.

8. A hydraulic apparatus comprising in combination a cylinder block, a shaft pivoted on the block, an operating handle secured to the shaft, a piston actuating lever secured to the shaft, a pair of pivot pins carried by the lever at diiferent distances from the shaft, a pair of pistons operatively connected to the pivot pin which is closer to the shaft, a single larger piston operatively connected to the pivot pin which is farther from the shaft, a cylinder in the cylinder block operatively receiving each piston, a liquid reservoir, 8, separate inlet passage from the reservoir into each cylinder, an inlet check valve between each cylinder and the reservoir, a common outlet for both cylinders, an outlet check valve between the common outlet and each cylinder, a biased valve control member normally out of restrictive relation with the inlet check valves, pressure operated means mounted to oppose the bias of the valve control member, and pressure transmitting means operatively connecting the common outlet and the pressure operated means, to operate the pressure operated means on a predetermined increase in outlet pressure, thereby to move th biased valve control member into valve -opening relation to one of the inlet check valves.

9. A hydraulic apparatus comprising, in combination, a cylinder block, a plurality of cylinders formed in the cylinder block, an operating handle fulcrumed on the cylinder block, a piston operatively mounted in each cylinder, means operatively connecting the pistons to the handle, a liquid reservoir, a separate inlet passage from the reservoir into each cylinder, an inlet check valve between each cylinder and the reservoir, a common outlet for both cylinders, an outlet check valve between the common outlet and each cylinder, a cylindrical valve chamber formed in the cylinder block, a floating piston mounted in the cylindrical valve chamber, a pin operatively connected to the piston and movable by the piston into unseating engagement with the inlet check valve of one of the cylinders, a, spring mounted to exert a biasing force on the piston away from such unseating movement, a second spring mounted to exert a force on the piston opposed to that, of the first spring, adjusting means mounted to adjust the relative forces of the two springs, and pressure transmittingmeans conthe piston opposed to'the biasing spring to move the pin into unseating engagement with its check valve on a predetermined increase in pressure in the common outlet.-

10. A hydraulic apparatus comprising, in combination, a cylinder block, a plurality of cylinders formed in the cylinder block, an operating handle fulcrumed on the cylinder block, a piston operatively mounted in each cylinder, means operatively connecting the pistons to the handle, a

liquid reservoir, a separate inlet passage from the reservoir into each cylinder, an inlet check valve between each cylinder and the reservoir, 9, common outlet for both cylinders, an outlet check valve between the common outlet and each cylinder, a cylindrical valve chamber formed in the cylinder block, a floating piston mounted in the cylindrical valve chamber, a pin operatively connected to the piston and movable by the piston into unseating engagement with the inlet check valve of one of the cylinders, a spring mounted to exert a biasing force on. the piston away from such unseating movement, a second spring mounted to exert a force on the piston opposed to that of the first spring, adjusting means mounted to adjust-the relative forces of the two springs, pressure transmitting means connected to the common outlet and to the side of the piston opposed to the biasing spring to move the pin into unseating engagement with its check valve on. a predetermined increase in pressure in the common outlet, a pressure release passage from the common outlet to the reservoir, and a pressure release valve mounted in the pressure release passage, said pressure release valve having a closed condition to prevent flow of liquid from the common outlet to the reservoir through the passage, and an open condition to release liquid from the common outlet through the passage to the reservoir.

11. In a multi-stage pressure generator, a plurality of cylinders, a fluid reservoir, valve controlled conduit means connecting the cylinders with the reservoir and with an outlet, a piston operatively mounted in each cylinder, lever means connectlng'the pistons to a common fulcrum, and pressure actuated release means operatively connected with one of said cylinders to make ineffective the motion of the piston in said one cylinder on the attainment of a predetermined outlet cylinders to make ineifective the motion of the piston in said one cylinder on the attainment of a predetermined outlet pressure.

13. In a multi-stage pressure generator, a plurality of cylinders, a fluid reservoir, valve controlled conduit means connecting the cylinders with the reservoir and with an outlet, a piston mounted in each cylinder, lever means of difierent lengths connecting the pistons to a common fulcrum, and pressure actuated release means operatively connected to the cylinder having its piston operated by a longer of said lever arms to make ineffective the motion of the piston in said latter cylinder on the attainment'of a predetermined outlet pressure.

V plurality of cylinders, a fluid reservoir, a common outlet from said cylinders, ,a piston mounted in each cylinder, conduits connecting said reservoir to said cylinders and other conduits connecting said cylinders to said outlet, inlet and outlet check valves associated with each said cylinder respectively controlling flow into and out of said cylinders through said conduits in response 12 a to reciprocation oi'said pistons, means for reciprocating said pistons, pressure actuated means -for moving the inlet check valve associated with one of said cylinders to open position, means ren-i dering said pressure actuated means responsive to the fluid pressure at said outlet, and means inhibiting actuation of said pressure actuated means until a fluid pressure of p nin value is attained at said outlet.

HERBERT E. PAGE.

REFERENCES I The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 753,530 Ten Eyck Mar. 1, 1904 1,781,404 McNab Nov, 11, 1930 so 1,829,451 McNab Oct. 27, 1931 McGee June 15, 1937

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