US1955278A - Hydraulic press - Google Patents

Description

April 17, 1934. J, P. FERRIS ET AL 1,955,278

HYDRAULIC PRESS Filed Feb. 24, 1930 6 SheetS- -Sheet 1 INVENTOR. JUHN F. FERHIE.

JAMES K.DULH3LAS.

A TTORNE Y.

April 17, 1934. FERRls ET AL 1,955,278

HYDRAULI G PRES S Filed Feb. 24, 1930 6 Sheets-Sheet 2 I N V EN TOR.

y JAMES KDBUGLAS.

A TTORNEY.

April 17, 1934.

J. P. FERRIS ET AL HYDRAULI C PRE S S 6 Sheets-Shae: 5

Filed Feb. 24, 1930 INVENTOR. JDHN P.FEHRIS. By JAM SKDBUQLAS.

A TTORNE Y.

April 17, 1934. J. P. FERRIS El AL 1,955,278

' HYDRAULIC PRESS Filed Feb. 24'; 1950 6 Sheets-Sheet 4 A TTORNE Y.

April 17, 1934. J. P. FERRIS Er AL 11,955,278

HYDRAUL I C PRE S S Filed Feb. 24, 1930 6 SheetsSheet 5 I N V EN TOR. JBHN PF'ERRI 3. y JAMES K.D[]LJEL.AS.

A T'I'ORNE Y.

April 17, 1934. J. P. FERRIS ET AL HYDRAULIC PRESS Filed Feb. 24, 1930 6 Sheets-Sheet 6 INVENTOR. JEN-IN F.FERF IS. y JAMES KDULJBLAS.

A TTORNEY.

Patented Apr. 17, 1934 UNITED STATES PATENT OFFICE -munmumc muss John P. Ferris and James K. Douglas, Milwaukee,

Wis., assignors to The Oilgear Company, Milwaukee, Via, a corporation of Wisconsin Application February 24, 1930, Serial No. 430.999 8 Claims. (01. 138-17) novel combination and arrangement of parts for.

increasing. the available tonnage capacity of the press without requiring excessive hydraulic pressures or unduly large plunger diameters.

Another object is the provision in a press or the like of an improved pump fed hydraulic system for effecting rapid movement of the ram during idle strokes thereof and forautomatically applying a very high driving force to the ram while engaged with the work.

Another object is the provision in a hydraulic operating system for presses and the like of improved hydraulic valve operating mechanism designed to insure completion of the valve movement through dead center positions.

Other objects and advantages will appear from the following description of an illustrative em- 55 bodiment of the present invention.

In the accompanying drawings:-

Figure 1 is a front elevation of a hydraulic press embodying the present invention.

Fig. 2 is a side elevation thereof.

Fig. 3 is a diagrammatic illustration of the hydraulic system for operating the press.

Figs. 4, 5 and 6 are sectional views of a group of valves shown in Fig. 3, illustrating various characteristic positions thereof.

Fig. 7 is a sectional view of another of the valves shown in Fig. 3, illustrating the same in a different operating position.

The press selected for illustration comprises the usual standards 10, mountedv upon an appropriate base 11, and supporting a head-12. The head 12 is provided with a central opening 13 to accommodate the ram 14. In this instance the ram 14 is carried by a hydraulically actuated plunger 15 reciprocable within a cylinder 16 mounted on the head 12. The plunger 15 is single acting and is connected in tandem with a double acting piston 1'7 through a heavy rod 18 having a close sliding fit in the head 19 of the cylinder 16. The piston 17 is closely fitted for reciprocation within a second cylinder 20 which is seated upon the upper end of cylinder 16.

A removable end head 21 closes the upper end of cylinder 20, and heavy tension rods 22, passing through the head 21, secure both cylinders to the head of the press.

For' a purpose which will later appear the plunger 15 is preferably of less diameter than the piston 17 so that the effective pressure area thereof is less than the effective pressure area of the bottom face of the piston. It will also be noted that the effective pressure area of the bottom face of piston 17 is reduced by the member 18 so that-this area is less than the effective pressure area of the top face of the piston. The piston 17 and plunger 15 together form a differential piston having three different effective pres? sure areas.

A pipe 23 connected with the lower end of cylinder 20 is controlled by a valve A; a pipe 24 connected withthe upper end of cylinder 20'is controlled by a valve B; and branch pipes 25 and 26, communicating through a pipe 27' with the upper end of cylinder 16, are controlled by the valves A and B, respectively. Valves A and B are of similar construction and both are mounted one one of the press standards 10. Each comprises a castinglongitudinally bored to receive a plunger having two heads 28-28 and 29-29' closely fitted therein. Heads 28 and 29 of valve A control pipes 23 and 25, respectively; and heads 28' and 29 of valve B control pipes 24 and 26, respectively. The opposite ends of the bore of each valve communicate with each other through a pipe 3030', pipe 30 communicating with an exhaust pipe 31 and pipe 30' with an exhaust passage 32. A supply pipe 33 leads to'the bore of valve A intermediate the heads 28 and 29, and a supply passage 34 leads to the bore of valve B intermediate the heads 28' and 29'. The arrangement is such that when the plungers of valves A and B are in the left positions of Fig. 3, supply pipe 33 communicates with pipe 23 and pipe 25 is blocked, and supply passage 34 communicates with pipe 26 and exhaust passage 32 communicates with pipe 24 through pipe 30'. When the plunger of valve B is shifted to the right position of Fig. 4 supply passage 34 communicateswith pipe 24, and pipe 26 is blocked. When the plunger of valve A is shifted into the right position of Fig. 5 supply pipe 33 communicates with pipe 25, and pipe 23 communicates with exhaust bored to receive a valve plunger having three spaced heads 35, 36 and 37. The head 36 controls communication between a supply pipe 38 and the'passage 34, and also controls communication between the pipe 38 and an exhaust pipe 39, which communicates with exhaust pipe 31. The head 35 controls communication between the exhaust passage 32 and the pipe 39. The right end of the bore of valve C is closed by a plate 40 through which a pipe 41 is connected; and the left end of the bore is closed by a block 42 bored to receive an auxiliary plunger 43, constituting an extension of the main plunger. A pipe 44 communicates with the bore in block 42. The arrangement is such that when the plunger of valve C is in the right position of Fig. 3, both passages 32 and 34 of valve B are blocked and the supply pipe 38 communicates with the exhaust pipe 39; and when this plunger is shifted into the left position of Figs. 4, 5, and 6 the supply pipe 38 communicates with the passage 34, and the exhaust passage 32 communicates with the exhaust pipe 39. The plunger of this valve is shifted into one position or the other by pressure in pipes 41 and 44 in a manner to be later explained.

Both supply pipes 33 and 38 are connected through a pipe 45 with an appropriate hydraulic pressure source such as a variable displacement pump 46. The pump shown is of a type fully described in the prior patent to Walter Ferris, No. 1,558,002, issued October 20, 1925. This pump is driven at constant speed through a pulley 47 and delivers liquid through pipe 45 at a rate dependent upon the setting of a hand wheel 48. The pump receives liquid from a sump 49 in the base of the pump housing, the sump being replenished by liquid returned thereto through the exhaust pipe 39. A low pressure relief valve 39 in the pipe 39 maintains a low back pressure therein. A high pressure relief valve 50 connected to the pipe 45 protects the pump and system against excessive pressures, the exhaust from the relief valve 50 being returned to the sump through a pipe 51. A gear pump 52 of a well known type (ordinarily contained in the pump housing) also receives liquid from the sump and discharges through a pipe 53. A low pressure relief valve 54 connected with pipe 53 determines the pressure therein and directs excess liquid therefrom through a pipe 55 to the sump. A pipe 56, communicating with the sump through pipe 55, leads to the upper end of the cylinder 16 through the pipe 27. A check valve 57 in the pipe 56 prevents the escape of liquid therethrough from pipe 27 but permits liquid to flow from the sump to the cylinder 16 during an idle down stroke of the plunger 15.

The plungers of valves A and B are actuated by liquid supplied through and controlled by two pilot valves D and E. The plunger of each of valves A and B terminates at one end in an auxiliary plunger having four spaced heads 5858',

7 59-59, 60-60, and 61-61 closely fitted in the bore of an end head 62-62, and also at the other end in a similar auxiliary plunger having spaced in the bore of the other end head 67-67. Each auxiliary plunger contains a longitudinal passage 68 open to the end of its bore and communicating with radial ducts 69 and 70 therein.

A pipe 71 leading from the pilot valve D to the bore in block 62 contains a low pressure relief valve 72 for effecting a reduction in pressure therein and also a choke coil '73 for reducing the rate of flow therethrough. A small pressure accumulator 74 is also connected with the pipe 71. A pipe 75 controlled by head 59 connects with pipe 71 between the accumulator and relief valve, and a pipe 76 controlled by head 58 and conta n g a check valve 77 connects with pipe 75. Similarly a pipe 71' leading from the pilot valve E to the bore in block 62' contains a similar relief valve 72 and choke coil 73' and connects with a similar accumulator 74'. Also a pipe 75' controlled by head 59' connects with pipe 71, and a pipe 76 controlled by head 58' and containing a check valve 77'.connects with pipe 75'.

A pipe 88 leading from the pilot valve E to the bore in block 67 contains a check valve 89 and choke coil 90 and communicates with a pipe 91 controlled by the head 64; and a pipe 92 containing a check valve 93 and communicating with pipe 91 is controlled by the head 63*. Similarly a pipe 88' leading from the pilot valve D to the bore in block 67' contains a relief valve 89 and choke coil 90' and communicates with a pipe 91? controlled by the head 64'; and a pipe 92 containing a check valve 93"and communicating with the pipe 91' is controlled by the head 63. A small pressure accumulator 94 is connected with th pipe 88.

The pilot valve D comprises a plunger having three heads 95, 96, d 97 closely fitted within the bore of a block cons tuting an integral part of the valve A. The opposite ends of the bore communicate through a passage 98 which connects with a drain pipe 99. The end'heads and 97 control the pipes'll and 88', and the intermediate head 96 controls a pipe which communicates with the pipe 23and contains a high pressure relief valve 101. The arrangement is such that when the plunger of .valve D is in the left position of Fig. 3 pipe 100 communicates with pipe 88 and pipe 71 is open to drain pipe 99 through passage 99; and when shifted into the right position of Figs. 4 and 5 pipe 100 communicates with pipe 71 and pipe 88' communicates with the drain pipe 99.

Thepilot valve E comprises a plunger having four heads 102, 103, 104, and 105 closely fitted in a bore in a block integral with valves B and C. A passage 106 connects the opposite ends of the bore and communicates with a drain pipe 107. A radial duct 108 between heads 102 and 103 communicates through a longitudinal passage 109 in the plunger with a radial duct 110 between heads 104 and 105. Pipe 88 is controlled by head 103 and pipe 71 is controlled by head 104, A pipe 111, connected with the pipe 25, communicates with the annular space between the heads 103 and 104. Pipe 111 contains a high pressure relief valve 112. The arrangement is such that when the plunger of valve E is in the left position of Fig. 8 pipe 111 is blocked and pipe 71' communicates with pipe 88'through the passage 109 and ducts 108 and 110; and when this plunger is shifted into the right position of Figs. 4 and 5 pipe 111 communicates with pipe 71; and pipe 88-communicates with the drain pipe 107 through the passages 109 and 106.

The plungers of both pilot valves D and E are connected through a rod 113 so that they operate as a unit. Each of these plungers terminates at one end in a reduced extension forming an auxiliary plunger 114 or 115 working in a bored end head 116 or 117; A pipe 118, communicating with the end head 116 of valve D, leads to and is controlled by the head 65 of an auxiliary plunger of valve 8; and a pipe 119, communicating with the end head 117, of valve E, leads to and is controlled by the head- 60' of the other auxiliary plunger of valve B. A drain pipe 120 controlled by head 65' leads to the sump and a pipe 121 controlled by head 60' connects with drain pipe 120. The arrangement is such that when the valve 3 is in the left position of Fig. 3 pipe 118 150 communicates with the drain pipe 120, and pipe 119 communicates with the pipe 75 through ducts 108 and 110 and passage 109; and when valve B assumes the position shown in Figs. 4 and 5 pipe 118 communicates with pipe 91' through the ducts 69 and and passage 68, and pipe 119 communicates with the drain pipe 120 through pipe 121.

The head 65.0f one auxiliary plunger of valve A controls communication between the duct 70 and a drain pipe 122, and the head 60 of the other auxiliary plunger thereof controls communication between a drain pipe 123 and duct 70, and head 60 also controls communication between the drain pipe 123 and a pipe 124 which leads to the auxiliary actuating cylinder 125 of a starting valve F to be later described. It will thus be noted that when the valve A assumes the position of Fig. 3 pipe 124 is open to the drain pipe 123, and pipe 91 is open to the drain pipe 122 through the ducts 69 and 70 and passage 68; and when valve A assumes the position of Figs. 4 and 5 pipe 124 communicates with pipes 71, 72, and through passage 68 and ducts 69 and 70, and the drain pipes 122 and 123 are both blocked.

The starting valve F comprises a block bored to receive a plunger having two narrow heads 126 and 127 and an elongated end head 128 which works in the cylinder 125. A passage 129 connecting the opposite ends of the bore communicates with a drain pipe 130. A pipe 131, which normally communicates with the gear pump delivery pipe 53 through a valve G, leads to the annular space between the heads 126 and 127. The pipe 41 from the right end of valve C connects with the valve F and is controlled by the head 127. A wide annular channel 132 forms a by-pass around the head 126, when the plunger of valve F is in the left position of Fig. 3, so that pipe 131 then communicates with the drain pipe 130 through the passage 129; and with the valve plunger in this left position pipe 41 also communicates with the drain pipe 130. Longitudinal grooves 133 in the head 128 also effect communication between the pipe 124 and drain pipe 130 when the valve plunger is in this left position.

When the valve plunger is shifted into the right.

position of Fig. 7 however, pipe 131 communicates with pipe 41, heads 126 and 127 separate the pipes 131 and 41 from the drain pipe 130, and grooves 133 are blocked.

The plunger of valve F is mechanically operated toward the right through a stem 134 projecting from the left end thereof. An operating lever 135 rockably supported on a fixed stub shaft 136 carries a dog 137 pivoted as at 138 thereon. Coacting stops 139 and 140 on the dog and lever limit the swing of the dog in one direction, the dog being permitted to swing counterclockwise from this limiting position. The lever and dog are so positioned with respect to the stem 136 that when the lever is depressed into the lower extreme position shown in dotted lines in Fig. 3 the valve plunger is shifted toward the right imtil the dog 137 clears the path of the stem. In this position the valve plunger is free to be returned toward the left by pressure trans mitted through pipe 124. to the cylinder 125. The pivotal mounting of the dog 137 permits return of the lever 135 to the full line position of Fig. 3 after the valve plunger has been returned to the left. A stop pin 141 in an appropriate bracket 142 limits the down stroke of the lever 135.

Pin 141 thusserves as a stop pin when the press is to execute a single down stroke only.

When a repeat operation is desired a second stop pin 143 is inserted in the bracket 142 above the pin 141. When pin 142 is inserted the lever 136 can be only partially depressed to the position shown in Fig. 7 in which position the dog 137 prevents the return of the valve plunger toward the left in spiteof pressure transmitted to the cylinder 125. .As will'be later described the press will repeat its cycle as long as-the lever 135 is held against the pin 143.

The valve G is an emergency valve by which the press can be stopped at any, .point in the down stroke thereof. This valve comprises a block bored to receive a plunger having two heads 144 and 145. The opposite ends of the bore communicate through a passage 146 which connects with a drain pipe 147. The head 144 controls a pipe 148 which connects with pipe 71', and head 145 controls the pipe 131., Pipe 53 always communicates with the annular space between the heads 144 and 145. The valve plunger is provided with an operating stem 149 equipped with an appropriate handle 150 for convenient manipulation. The normal position of this valve is shown in-Fig. 3 in which position pipe 148 is blocked by head 144 and pipe 53 is connected with pipe 131 so, as to maintain pressure therein. However when the plunger of this valve is shifted to the left by pulling the handle 150 pipe 131 is opened to the drain pipe 147 through the passage 146, and pipe 148 is opened to the pressure pipe 53. Pressure is thus transmitted to the end head 62' of valve B to return the plunger thereof to the left position of Fig. 3, after; which this pressure is transmitted through the duct 70 and pipe 119 to the end head 115 of valve E to thereby return both pilot valves D and E to the left position 'of Fig. 3, and this same pressure transmitted through duct 69 and pipes 75, '71, and 88 to the end head 67 of valve A returns valve A to the left position of Fig. 3.

Operation.

Fig. 3 illustrates the position of the various parts with the press at rest and'ready to begin an operating cycle. Referring to this figure it will be noted that the plunger of valve C is in its right extreme position so that pipe 38 is connected with the exhaust pipe 39 and thus discharges through the low pressure relief valve 39' which thus determines the pressure in pipes 38, 39 and 33; and that the passages 32 and 34 of valve B are blocked. It will also be noted that the plungers of both valves A and B are in their left extreme positions so that pipes 25 and 26 leading to the upper end of cylinder 16 are blocked; that pipe 24 leading to the upper end of cylinder 20 is blocked; and that the pipe 23 leading to the lower end of cylinder 20 is exposed to the low pressure then existing in pipe 33 and the press ram is, thus supported in the upper position shown. It will alsobe noted that the plungers of both pilot valves D and E are in their left extreme positions so that pipe 100 is connected to pipe 88'.

To start the press on a one stroke cycle th operator depresses the lever 135 into the dotted line position of Fig. 3 to thereby shift the plunger of valve F into the position shown in Fig. 7. Pipe 41 then transmits pressure from pipe 131 to the end of the piston 37 to thereby shift the valve C into the left position of Fig. 4. Pipe 38 is thus dispump 46 (since the pipe 39 and relief valve 39 have been disconnected from pipe 26) The press ram however is sustained in upper position by reason of the fact that the lower face of piston 17 is also exposed to full pump pressure through the pipes 23 and 33. The increased pressure in pipe 23 transmitted through pipe 100 opens the relief valve 101 so that liquid then enters pipe 88 and flows through the pressure reduction .valve 89' and choke coil 90' into the end head 67 of valve B to thereby shift the plunger of this valve into the rightposition of -Fig. 4, in which position pipe 26 leading to the upper end of cylinder 16 is blocked bythe head 29' and pipe 24 leading to the upper end of cylinder 20 is connected through passage 34 with the pipe 38 leading from the pump 46, and the press ram starts down. It will be noted that the lower end of cylinder 20 is also connected at this time with the pipe 33 through pipe 23 so that the discharge from the lower end of this cylinder passes through pipe 33 into pipe 38 and is thus added to the discharge from the pump 46 to effect a rapid downward travel of the press ram.

During this downward idle stroke of the ram 15 liquid is drawn into the upper end of cylinder 16 through the pipes 27 and 56 and check valve 57 from the sump in the base of the pump; so that the cylinder 16 is maintained in a flooded condition.

It will be noted that the choke coil 90 restricts the flow of liquid through pipe 88' and thus retards the movement of the plunger of valve B toward the right. During this movement of the valve plunger liquid escapes from the end head 62' through. the pipes 76, 75, 71, 88, and 91 to the drain pipe 122 until the pipe 76 is blocked by the head 58 of the auxiliary plunger, whereupon a small body of liquid is trapped in the end head 62' which serves as a cushion to prevent the valve plunger from pounding against the end of the head 62'.

It will also be noted that as the flow through pipe 88' is retarded by the choke coil 90 liquid continues to enter pipe 88 from the pipe 100 to thereby charge the accumulator 94. The accumulator 94 when thus charged serves as an auxiliary pressure source from which liquid continues to flow through pipe v88' after the flow in pipe 100 has ceased.

When the plunger of valve B reaches the right position of Fig. 4, duct communicates with pipe 118 and liquid from pipe 88' passes therethrough to the end head 116 of pilot valveD to thereby shift the plungers of both pilot valves D and E into the right position of Fig. 4. During this action of valves D and E liquid escapes from the end head 117 of valve E through the pipe 119 to the drain pipe 121;

The press ram continues its rapid downward travel under the driving action of the piston 17, with both ends of the cylinder 20 open to the discharge side of the pump 46, until the ram engages and is resisted by the work. Then as the work resistance increases the pressure in the pipes 23 and 24 increases until the relief valve 101 again opens under the pressure transmitted from pipe 23 through pipe 100. Liquid from pipe 100 then flows through valve D into pipe 71 (Fig. 4) and through the pressure reduction valve 72 (Fig. 3) and choke coil 73 into the end head 62 of valve A to thereby shift the plunger of valve A into the right position of Fig. 5, in which position the pipe 23 leading from the lower end of cylinder 20 is connected with the exhaust .upper ends of their cylinders.

pipe 39 through pipes 30 and 31, and pipe 25 leading to the upper end of cylinder 16 is connected with the pressure pipe 33 leading from the pump. Since the pipe 24 leading to the top of the cylinder 20 remains connected to the pump delivery pipe 38 through the valves B and C the press ram continues its down stroke under the combined pressure transmitted from the pump to the upper faces of the piston 17 and plunger 15. a

It will again be noted that the choke coil 73 restricts the flow through pipe 71 so as to retard the movement of the plunger of valve A and to effect charging of the accumulator 74 by the flow from pipe 100. During the movement of the plunger of valve A toward the right liquid escapes from end head '67 through the duct 70 and drain pipe 122 until pipe 122 is blocked by head 65, whereupon a body of liquid is trapped in the head 67 which serves to cushion the final end thrust of the valve plunger.

It will also be noted that when the plunger of valve A reaches the right extreme position of Fig. 5 pipe 75 communicates with pipe 124 through the ducts 69 and 70 and passage 68, so

that pressure is thus transmitted from the accumulator 74 to the cylinder 125 of valve F to thereby return the plunger thereof to the left position of Fig. 3. Excess liquid from the accumulator 74 then escapes through the grooves (Fig. 3) and passing through the pressure reduction valve 72' and choke coil 73' into the end head 62 of the valve Bto thereby shift the plunger of this valve into the left position of Fig. 6, in which position pipe 24 leading from the upper end of cylinder 20 is connected to the exhaust pipe 39 through the pipe 30' and passage 32, and pipe 26 communicating with the upper end of cylinder 16 is connected with the pressure pipe 38 through the passage 34.

When the plunger of valve B reaches the left position of Fig. 6, liquid from the pipe 71 flows through passage 68, duct 70, and pipe 119 into the end head 117 of pilot valve E to thereby shift the plungers of both pilot valves into the' left position of Fig. 6, liquid escaping from the end head 116 of valve D through pipe 118 to the drain pipe 120. When the pilot valve E has thus been re turned to this left position pipe '71 is connected to the pipe 88 through the valve E and liquid flows through the check valve 89 and choke coil 90 into the end head 67 of the valve A to thereby shift the plunger thereof into the left position of Fig. 6, in which position pipe 25 is blocked, and pipe 23 from the lower end of cylinder 20 is connected to the pressure pipe 33 and the. press ram rises. During this upward travel of the ram liquid escapes from the cylinder 16 through the pipes 27, 26, and 38 and entering the pipe 33 adds to the discharge from the pump 46 to thus cause the ram to move rapidly.

This upward rapid travel of the ram continues with the lower face of piston 17 and the upper end of plunger 15 exposed to the discharge of the pump until the piston and ram stall against the This causes an abrupt rise in pressure in pipes 23 and 25 causing the relief valve 101 to open. Relief valve 112 remains closed because pipe 111 is then blocked by the plunger of valve E. When relief valve 101 opens liquid passes from pipe 100 through pipes 88v and 44 into the end head 42 of valve C and, since the pressure in pipe 41 has been destroyed by the previous return of valve F to the position of Fig. 3, valve C is returned to the position of Fig. 3 by the pressure applied to the auxiliary plunger 43 thereof. This action of valve C connects pipe 38 with the'drain pipe 39 so that the discharge from the pump 46 escapes through the low pressure relief valve 39. All of the parts have thus been returned to their original positions shown in Fig. 3 and the press is ready to begin a new cycle.

If continuous operation of the press is desired the pin 143 is inserted in the bracket 142 and the lever 136 is depressed against the pin 143, as indicated in Fig. '7, and held in that position throughout the desired period of operation.

When so held the plunger of valve F is retained in the. right position of Fig. '7 so that pressure is thus maintained within the pipe 41 and therefore against the head 37 of the valve C. This pressure is sufficient to maintain the valve C. in the left position of Fig. 6 against the pressure transmitted to the auxiliary plunger 114 through pipe 44 when the relief valve 101 opens at the end of the up stroke of the press ram, so that the pressure thus transmitted through the relief valve merely shifts the plunger of valve' B to the right in the manner previously described to thereby cause the ram to start down on a new cycle.

As previously pointed'out the down stroke of the ram may be stopped at any point by pulling the handle 150 of valve G and'thus effect the prompt return of the several valves A, B, D and E to the left positions shown in Fig. 3.

Various changes may be made in the embodiment of the present invention hereinabove described without departing from. or sacrificing any of the advantages of the invention as defined in the appended claims.

We claim:-

1. In a hydraulic press the combination of a ram, a differential piston for operating the same, said piston having three pressure faces, a pump, means including a valve for connecting the discharge side of said pump with one of said faces, means including a second valve for connecting the discharge side of said pump with another of said faces, and hydraulic connections controlled by both of said valves for connecting the discharge side of said pump with the third of said faces.

2. In a hydraulic press the combination of a ram, a differential piston for operating the same, said piston having three pressure faces, a pump, means including a valve for connecting the discharge side of said pump with one of said faces, means including a second valve for connecting the discharge side of said pump with another of said faces, hydraulic connections controlled by both of said valves for connecting the discharge side of said pump with the third of said faces, and automatic means for operating'said valves in definite sequence.

3. In a machine of the character described the combination of a reciprocable member, a piston for operating the same, a pump, a valve controlling communication between said pump and piston, hydraulically actuated means for operating said valve, means for retarding the movement of said valve, and a hydraulic pressure accumulator for supplying driving liquid to said hydraulically actuated means to complete the movement of said valve.

4. In a machine of the character described the combination of a reciprocable member, a hydraulic motor for operating the same, a pump, a valve controlling communication between said pump and motor, means actuated by pressure supplied from said pump for operating said valve, means for retarding the movement of said valve, and a hydraulic pressure accumulator energized by pressure supplied from said pump for completing the movement of said valve.

5. In a machine of the character described the combination of a cylinder, a plunger therein, a member driven by said plunger, a second cylinder, a piston therein of greater diameter than said plunger, a rod in one end of said second cylinder connecting said piston and plunger, a pump, and means including valve mechanism operable to connect said pump to both ends of said second cylinder to effect rapid movement of said member in one direction, to connect said pump to said first named cylinder and to one end of said second cylinder to increase the driving force applied to said member, or to connect said pump to said first named cylinder and to the rod end of said second cylinder to effect rapid movement of said member in the opposite direction.

- 6. In a machine of the character described the combination of a hydraulically driven member, a pump, a hydraulic circuit fed by said pump for driving said member, said circuit including a valve for controlling the movement of said member, hydraulically actuated means energized from said circuit for operating said valve, and a hydraulic pressure accumulator energized by said circuit and hydraulically connected with said last named means to complete themovement .of said valve.

7. In a machine of the character described the combination of a hydraulically driven member, a pump, a hydraulic circuit fed by said pump for driving said member, said circuit including a hydraulically actuated valve for controlling the movement of said member, means including a hydraulic pressure accumulator energized from said circuit for operating said valve, and means for resisting discharge of liquid from said accumulator to said circuit.

8. In a machine of the character described the combination of a hydraulically driven member, a pump, a hydraulic circuit fed by said pump for driving said member, said circuit including a. valve operable to control the movement of said member, means including a hydraulic pressure accumulator energized from said circuit for operating said valve, and a pilot valve for controlling said first named valve.

JOHN P. FERRIS. JAMES K. DOUGLAS.

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