US2014162A - Hydraulic press - Google Patents

Description

Sept. 10, 1935. E ENEDEK ET AL 2,014,162

HYDRAULIC PRESS Filed Aug. 8, 1931 9 Sheets-Sheet 2 RELIEF VALVE I 3uvcntors 1 Fa 6M P ,1935. E. BENEDEK E! AL 2,014,162

HYDRAULIC PRES 5 Filed Aug. 8, 1931 9 Sheets-Sheet 3 P 1935. El BENEDEK ETAL 4 2,014,162

HYDRAULI C PRES S Filed Aug. 8, 1931 9 Sheefos-Shet 4 QQZ 7%. attorneys.

P 1935. E. BENEDEK ET AL 2,014,162

HYDRAULIC PRES 5 Filed Aug. 8, 1931 9 Sheets-Sheet 5 I i -q G Za; Inventors,

I I I Sept. 10, 1935. E. BENEDEK ET AL HYDRAULIC PRESS 9 Sheets-Sheet 6 Filed Aug. 8, 1931 Sept 1935- E.IBENEDEK ET AL 2,014,162

HYDRAULI C PRES 5 Filed Aug. 8, 1931 9 Sheets-Sheet 7 M Gnomcgs.

Sept. 10, 1935. ,E. BENEDEK ET AL 2,014,162

' HYDRAULIC PRESS Filed Aug. 8, 1931 9 Sheets-Sheet 8 MYW Snventors, I

Sept. .10, 1935. E. BENEDEK ET AL 2,014,162

' HYDRAULIC PRESS I Filed Aug. 8, 1931 9 Sheets-Sheet 9 i we 4; (lttomegs.

Patented Sept. 10, 1935 a UNITED STATES PATENT OFFICE Application August 8, 1931, Serial No. 555,996

25 Claims.

This'invention relates generally to hydraulic presses and primarily has for an object to pronovel method of operating hydraulic presses whereby the elasticity of the pressure fluid is utilized to dampen the inertia force of the ram and to reverse the direction of travel of the mass of the ram at dead center or stroke change positions, thus providing for smooth high speed operation of the press.

Present conventional forms of hydraulic presses are of slow speedand long stroke design, and their reciprocation is controlled by valves interconnecting the press with the source of working fluid. The operation of such valves has been carried out by some auxiliary means, such as gear pump pressure or directly by fluid pressure only. In both cases, the'reaction of the valves to the working means requires a time interval, or in other words the reaction is in time lag in regard to the action, which time delay-oifsets the synchroni sm of the hydraulic circuit, which synchronism is one of the first requirements for high speed operation, where the several valves have to function simultaneously.

In such presses even greater disturbance has been caused at higher speeds by reason of the fact that conduit-sfilled with high pressure workingfiuid have to be opened almost instantaneously for the fluid in order to bypass it to another chamber of different pressure. Such quick opening or closing of fluid pressure communication presents a phenomena such as that presented by suddenly releasing a high tension spring. As the spring will carry out certain definite oscillations characterized by its spring constant, so the pressure fluid, by reason of the sudden opening or closing of control valves, will set up a certain type of pressure vibration, so that the automatic ontrol of thevalves by the pressure fluid is not quick enough clue to the pressure vibration of the fluid.

A further reason that ordinary present design prcs'es with valve control cannot attain higher is presented by the compressibility of the pressure fluid, notably of oil. The oil under ressure in a conduit-relatively long and of small cross section is capable of a slight amount of (Cl. Gil-54.5)

compression so that application of pressure at one end of the fluid column does not build up pressure at the other end of the column, until the volume of fluid diminished by compression has been replenished by new fluid. The resultant 5 time interval necessary to accomplish and compensate for this oil compression causes a lag in function of the control valves which is more or less fatal to attempts at attainment of high speed. operation. 10

It is well known that mechanical presses present advantages of high speed operation. Such presses of the fixedcrank short stroke type are capable of from to 300 cycles per minute. However, after a period of operation, these presses 15 become inaccurate at the end of their stroke, due to the wear of the crank bearings and crank pin, and therefore become impractical for close work such as fine-stamping and accurate die work. A

further undesirable feature resides in the inabil- 0 ity' of mechanical presses to stop or dwell at their lower dead center, that is, exert a squeezing action which is very essential in effecting exact die stamping and laminating operations. Adjustment of the press stroke is essential in order to 25 enable the-varying of the dwell interval at the end of the working stroke and obviously the mechanical type of press is not capable of such adjustment. An additional disadvantage is presented by the fact that the mechanical crank in ,30 such presses has to exert the total pressing force and impart it to the work, and consequently the size of the driving motor must be selected accordingly in order to assure development of the maximum power necessary to be put forth during all 35 periods of use.

Aside from the disadvantages of slow speed and complicated indirect controls hereinbefore alluded to, presses'of the hydraulic type arepreferable over the mechanical type in view of the smooth- 40 ness with which they can be made to operate, the minimization of wear, the accuracy of operation regardlessof wear, the adaptability to stroke adjustment and working stroke end dwell accomplishment, and the ability therein to take ad- 45 vantage of the well known hydraulic principle,- namely, that a high pressure applied to a small area can produce any amount of pressure on a larger area.

Therefore, our present inventive efforts are 50 directed to the production of a power press of the hydraulic type which embodies the advantages of both types of presses referred to above and at thesame time eliminates most if not all of the disadvantages alluded to. 55

In its more detailed nature the invention resides in the provision of a hydraulic press in which is included a reciprocating press ram, and a double acting reciprocating plunger pump so connected in cooperative relation to the ram that each stroke of the plunger in each direction of reciprocation efiects a stroke of the ram.

Another object of the invention is to provide means by operation of which the ram is caused to dwell at the end of the working stroke, resulting in a desirable squeezing engagement with the work.

Another object of the invention is to provide means for controlling the operation of the pump between the full discharge or maximum press ram stroke effecting phase through intermediate stroke degree phases to the no-discharge or press cut out phase. I

Other objects will in part be obvious and in part be pointed out hereinafter.-

To the attainment of the aforesaid objects and ends, the invention still further resides in the novel details of construction, the combination and arrangement of parts, all of which will be first fully described in the following detailed description and then particularly pointed out in the appended claims, reference being had to the accompanying drawings, in which:

Figure 1 is a somewhat diagrammatic vertical cross section of a hydraulic press embodying our invention, the section being taken on the line in elevation;

Figure 3 is an enlarged detail longitudinal section of one of the double acting control valves;

Figure 4 is a fragmentary side elevation illustrating the engagement of the bell crank lever with he cam thrust head;

Figure 5 is a detail central longitudinal section of the control cam;

Figure 6 is an end view illustrating the n delivery end of the cam;

Figure 7 is an end view illustrating the full delivery end of the cam.

Figures 8 and 9 are detail cross sections taken on the lines 88 and 99 on Figure 5 and illustrating cam face contours intermediately of the cam ends;

Figure 10 is a diagrammatic sectional view illustrating a reciprocating ram and reciprocating plunger pump connected cooperatively for constant stroke operation in accordance with the principles of our invention.

Figure 11 is a crank circle diagram on which the relation of pump plunger and press ram stroke, and also the adjustable dwell partaken of by the press ram, are indicated.

Figures 12, 13, 14, 15, 16, 17, 18, and 19 are diagrammatic sectional views showing the relative positions of the pump and press parts with the cam adjusted to the full discharge phase and the pump crank being illustrated in bottom dead center, 45", 90, and 135 after bottom dead center, at top dead center, 45?, 90, and,135 after top dead center positions respectively.

Figures 20, 21, 22, 23, 24, 25, 26, and 27 are diagrammatic sectional views showing the relative positions of the pump and press parts withthe cam adjusted to the partial discharge phase and the pump crank being illustrated in bottom dead center, 45, 90,. and 135 after bottom dead center, at top dead center, 45, 90, and 135 after top dead center positions respectively.

portion 22.

Figures 28, 29, 30, 31, 32, 33, 34, and 35 are diagrammatic sectional views showing the relative positions of the pump and press parts with the cam adjusted to the no discharge phase and the pump crank being illustrated in bottom dead center, 45, 90, and 135 after bottom dead center, at top dead center, 45", 90, and 135 after top dead center positions respectively.

In the drawings, in which like reference characters indicate like parts in all of the figures, A 10 generally designates the hydraulic press proper, which may be of any conventional double acting ram form, B the press operating plunger pump,

C the press ram operation controlling valve, D the cam which is shiftable to vary the operation of the control valve to bring about a full discharge, a variable partial discharge, or no discharge operation of the pump, E the cam position determining means, and F the mounting base on which the pump and the press may be 20 mounted as an individual structural unit.

The press A includes a base 5, a head 6 supported upon and spaced above the base by the standards or tie rods I, and the usual cylinder 8 which is shown as supported upon the head 6.

A piston plunger 9 is reciprocable in the cylinder 8 and from this piston a ram I0 depends through suitable gland equipment II, and the ram carries the usual platen I2 for engaging the work. I

A tank I3 is provided and in this particular disclosure is shown as mounted directly upon the cylinder 8. This tank is suitably connected in the hydraulic circuit and performs a function which will become apparent as the description progresses. I

For reasons which will be explained later, a stop slide I4 is provided and is guided for sliding movements as at I5 in the'press base. The slide or block I4 includes a recess or socket I6 and is connected as at I! to travel with the reciprocating ram III.

The pump Bincludes a cylinder I8, flange supported as at I9 upon a supporting base 20. The base 20 is provided with a guide bore2I and terminates at its lower end in a crank case portion 22, there being provided also a crank case base 23 which is flange connected as at 24 to the 'I'hrougithe medium of the connected flanges 24,'or otherwise, the pump B is secured as at 25 upon the mounting base F.

A crank shaft 26 is rotatably mounted in suitable bearings provided therefor in the pump casing sections 22 and 23, and is positioned so that the crank 21 thereof operates in the crank case formed compositely between said sections. One end of the crank shaft 26 is extended as at 28 to receive the cam D, and the other end is similarly extended as at 29 to provide for convenient connection with a suitable power applying motor (not shown) and for accommodating a fly wheel 30.

The crank 21 is connected by a pitman 3| and wrist pin 32 with a guide block 33 slidable in the guide bore 2I, and which has head-and-socket connection as at 34 with the reduced diameter stem 35 depending from the pump plunger or piston 36 which is reciprocable in the pump cylinder l8. The upper end of the cylinder is closed by a cover plate 31 which may be removably secured thereupon as at 38.

The control valve C includes a housing or casing 39 which is formed integrally with or attached to the pump cylinder I8, and is provided with a slide valve accommodating bore 40 which is disposed-with its axis parallel the axis of the pump tended beyond the housing 39 as indicated at 4! and is provided with an abutment head or cross pin 48 against which a compression spring, acts, said spring being interposed between the abutment 43 and the bottom of the valve housing 39. At its extreme pro ected end the control valve extension '41 is equipped with a roller which is adapted to ride the face of the cam D in a manner to be described in detail hereinafter.

The valve housing 39 is equipped with a main upper duct 5| and a main lower duct 52 which respectively provide for communication between the upper and lower portions of the pump cylinder l8 and the control valve bore 40. Upper, intermediate, and lower annular recesses respectively designated 53, 54, and 55 are associated with the upper part of the press and pump cylinders and communicate respectively through ports 56, 51, and 58 formed in the control valve housing 39 with circuit connections outside the housing, and which will be referred to in detail hereinafter. An additional or auxiliary duct 59 is provided which communicates directly between the upper recess 53 and the upper main duct 5i and cooperates with the ducts and ports above described in a manner hereinafter set forth.

The valve housing 39 is also provided with upper, intermediate, and lower recesses respectively designated 60, 6!, and 62, and which are associated with the lower parts of the press and pump 'cylinders and communicate through ports 63, 64,

and 65 respectively with the hydraulic circuit in a manner to be described hereinafter. This portion of the control valve housing is also equipped with an auxiliary duct 66 communicating directly between the recess 62 and the lower main duct 52 and serving a purpose similar to that of the upper auxiliary duct 59, as will become evident later in. this description.

The cam D is spline-connected as at 61 upon the extension 28 of the crank shaft so as to be rotatable with and yet axially adjustable with relation to said crank shaft extension, see Figure 2. By reference to Figures 5-9, it will be observed that the cam D is equipped with a varied cam face or peripheral contour, and has provision atone end for so acting upon the control valve as to bring about a no-delivery efiect of the pump operation, at its opposite end for causing a full discharge effect of the pump operation, and intermcdiately of its ends for bringing about partial effective operation of the pump in various desired degrees. For this purpose the cam is provided at its no-delivery end with diametrically oppositely disposed cam portions 68 which serve to move the control valve upwardly a maximum distance twice during each rotation of the crank shaft and two diametrically oppositely positioned flattened portions 69 active at dead center positions of the pump crank 21 to bring about a centered position of the control valve, seefor example Figures 28 and 32. The cam faceprovided by one of the cam portions 68 is constant throughout the full length of the cam D, as will be evident by reference to said Figures 5-9. See also Figures 12, 16, 20, 22, and 24, in which this same control valve position is occasioned by the same and other cam portions.

The non-constant portion of the cam D from a the double extension end above referred to over to the remaining or full discharge effecting end is gradually reduced as at (see Figures 5, 8, and 9) so as to permit the control valve to move below the center position in varying degrees, the 1 desirability of which will become evident when the operation of our improved press is described in detail hereinafter.

The maximum period of cam face reduction or depression is indicated at II, this being at the extreme full discharge effecting end of the cam, see Figures 5 and 7.

- The cam D, in addition to the bore which receives the crank shaft extension, is counter-bored as at 12 to accommodate a compression spring 73 which is compressed between the shoulder provided by the counterbore and the adjacent crank shaft bearing and serves to constantly urge the cam along the crank shaft extension in a direction tending to cause the no-delivery end of the cam to move into cooperative relation with the control valve roller 50. The cam race 15 abuts, the other ring of said race being abutted by a thrust head 16 which is bored to slidably and rotatably receive the cam extension 14. A stop pin 11 is adjustaby secured as at 18 in a threaded bore provided therefor in the end of the cam extension 74, and this stop pin projects axially through asuitable receiving bore in the thrust head 56 into position for at times entering the recess I6 formed in the slide block IA. The stop pin I? will enter the recess l6 whenever the recess is moved into receiving relation therewith, assuming of course that the action of the compression spring 13 is not opposed, However, the action of this spring is opposed during all normal operations of the press in a manner soon to be described, and for this purpose the head 76 is provided with laterally project-ing studs 19 (Figure 4).

The cam position determining means generally designated E includes a bell crank lever fulcrumed at 86 and having one arm 8| thereof forked and shaped to engage the abutment head carried studs 19 in the manner clearly illustrated in Figures 2 and 4 of the drawings. The other arm 82 of the bell crank is engaged by a spring 83 in a manner for constantly ,,engaging and holding the arm Bl in engagement with the head studs'i'9 in opposition to the compression spring 13. The spring 83 is stronger than the spring [3 and under normal conditions serves, through the arm and stud connection BI and 19, to hold the cam D against the moving tendency of the spring 13. The lever arm 82 is apertured to receive a stop bolt 84 which is secured to the mounting base F and includes an adjustable nut- 85 by which the at rest position of the fever arm 81-82, and consequently the operating position .of the cam D, may bedetermined. By loosenforce the cam D to the right until the head studs 79 stop against the lever arm' 8|. In this manner it is possible to adjust the cam D so as to cause any selected portion of its variedcontoured surface to be presented to the roller 50 for the purpose hereinbefore referred to.

At .the free end of the lever arm 82 a foot treadle 86 is pivotally mounted as at 81 and is provided with a depending heel 88 which is notched as at 89 to adjustably cooperate with a latch plate 90 mounted upon the base F. By depressing the lever 82 by use of the treadle the engagement of the lever arm 8| with the studs I9 is released and the spring I3 is permitted to force the cam bver into the no-delivery eifectreleased from its latched condition and the lever 8I82 permitted to move, under action of the spring 83, to return the cam to its adjusted operative position, and thus again bring about an active delivery of the pressure fluid to the press cylinder 8.

Our improved press operates on a closed hydraulic circuit, and this circuit includes a conduit 9I which connects between the upper recess 53 and port 56 and the upper part of the'press cylinder 8 and includes a spring loaded check valve 92 capable of opening only toward the port 56. A similar conduit 93 communicates between the lower recess 62 and port 65 and the lower portion of thepress cylinder 8, and it is similarly equipped with a spring loaded check'valve 94 capable of opening only toward the port 65. The

ducts 9I and 93 form suction ducts through which fluid is withdrawn from the press cylinder in a manner that will become apparent as the description progresses,

A conduit 95 communicates between the recess 55 and port 58 and the upper end of the press cylinder 8 and is valve controlled by a valve generally designated 95. A similar conduit 91 communicates between the recess 60 and port 63 and the lower end of the press cylinder '8 and is likewise controlled by a valve which is generally designated 98. The ducts 95 and 91 are pressure ducts through which pressure fluid is supplied to the respective ends of the press cylinder. 8.

Each of the valves generallydesignated 96 and 98 is of like construction (Figure 3) and includes a two part casing 99 having provision at I for connection directly or indirectly with the respective end of the press cylinder, and provision at IOI for connection with the duct 95 or 91, as the case may be, leading to the control valve housing ports 58 and 63. A valve cage I02 seats in the valve casing proper and accommodates a check ball I03, which in turn seats in and controls the passage provided through the .cage I02. The valve cage is slidable toward and from its seat on spider guides I and is spring Dressed toward its seat by a spring I 06', the load on which may be varied by means of the screw adjustment I01. It will thus be understood that the check ball I03 will permit free passage of pressure fluid into therespective ends which are sufllcient to movethe valve cage I02 delivery from said pump cylinder.

against the adjusted tension of the spring I06. It should be understood that the tension of the springs I06 is adjusted so that the resistance offered by the valve cage I02 always will be greater than the resistance ofiered by the check valves 5 92 and 94, so that suction through the check valves 92 and 94 will be favored over suction through the valves generally designated 96 and 98.

The valves 96 and 98 serve the purpose of permitting the ram piston to adjust its position properly in its cylinder, and. also to keep the hydraulic system free from shocks and any serious trapping of fluid. The return flow permitted through these valves enables the ram piston to adjust itself in its cylinder, especially at its dead center positions. Without such provision, should the pump pressure fluid deliveries at any time be not strictly proportional to the stroke of the press, serious trapping of fluid might result. The springs in these valves overbalance the springs in the check valves so that, during the stop period of the press, while the pump is running and the press ram is locked in its upper dead center position, any slippage in the system may be taken care of through the equalizing check valves without losing pressure fluid from the press cylinder toward the tank as might otherwise be the case.

The upper end of the pump cylinder I8 is connected with the upperend of the press cylinder 8 by a conduit I08 in which a check valve I09 is interposed at a point adjacent the pump cylinder and capable of opening only in the direction of The lower ends of the pump and press cylinders are similarly connected by a conduit H0 in which a similarly positioned and operable check valve III is interposed. The conduit H0 is capable of communication through an adjustably spring loaded low pressure relief valve H2 and conduit II3 with the interior of the tank I3, and the conduit I08 is similarly-capable of communication with said tank through the adjustably spring loaded high pressure relief valve Ill and the conduit II5 which may communicate directly with the tank or indirectly through a portion of the conduit I I3.

A by-passconduit II 6 connects the ports 51 and 64, and this by-pass conduit is capable of communication, through a conduit II I, with the interior of the tank I3. Communication between the recess 62 and port 65 and the tank conduit I I1 "is afiorded through a conduit II8 which connects the conduits H6 and 93 and is equipped with a check valve II9 permitting flow of fluid toward the recess andport but not back toward the tank i3. Thus, whenever it is necessary to draw through the port 65 a greater volume of fluid than can be drawn through the conduit 93, the conduit H8 and its connections with the a tank I3 can supply the demand.

Operation v In describing the operation of our improved press, we will assume the parts to be at rest with the press ram at top dead center or the 'upper limit of its stroke with the stop pin 11 in the slide block recess I6. It will be remembered that in this condition of the parts the cam D will be positioned with its no-delivery end in engagement with the control valve roller 50. By applying suitable motive power to the crank shaft 7 extension 29, the pump B will be put into operation, and the rotation of the crank 21 will be transmitted in the form of reciprocation to the pump plunger 35 through the connections 3|, 32,

"33, and 34. The cam D being in its no-delivery controlling position, the reciprocation of the plunger 36 will force no fluid into or withdraw no fluid from the press cylinder, the movement of the plunger serving only to bypass pressure fluid back and forth between the upper I and lower ends of the pump plunger.

In order to start operation of the press proper A, the treadle 86 is manipulated so as to release the notched heel 88 thereof fromthe latch plate 98 so as to permit the lever arm 82 to be elevated by the spring 83, thus causing the arm 8| to engage the head 16 and shift the cam D toward the left until the lever arm 82 engages the adjustable stop 85, when the cam will have been brought into the desired position of engagement with the roller, 58. The particular relation of the cam and roller may of course be determined by adjustment of the stop 85 in the manner hereinbefore described. This movement of the cam removes the stop pin 17 from the recess I6 and frees the slide block |4 so that it may reciprocate with the press ram. 'The reciprocation of the pump plunger 36 will now alternately force and withdraw the fluid of the closed circuit into and from the respective ends of the press cylinder 8 to impart reciprocation to the press ram in degree or stroke lengthcontrolled by the particular setting of the cam D. When the cam is set in its full delivery controlling position, each stroke of the plunger 38 will impart a full stroke to the press ram, and when the cam is set in one of its partial delivery effecting positions a portion only of the fluid displaced by the pump plunger 36 \1 will be effective in imparting travel to the press ram. The remaining portion, determined by the particular position of the cam D, will be bypassed in such a manner that it will not afiect press ram travel. I

When it is desired to stop the press, this can be accomplished by merely depressing the treadle 86 in the manner hereinbefore described in detail, permitting the stop pin H to enter the slide block recess l6 when it moves into position for receiving said stop pin, and thus automatically-enabling the spring .13 to shift the cam D to its nodelivery effecting position. In this condition of the parts, the motive power applied to the crank shaft extension 29 may be permitted to continue in operation if desired because the reciprocation of the plunger 36 will merely efiect by-passing of the fluid back and forth in the manner above referred to. The pump plunger equipment 36, 35 and the ram piston equipment 9, it] are so proportioned that the lower displacement areas of the plunger and ram piston bear the same ratio as the upper displacementareas of the plunger and the ram piston hear one to another, thus causing the fluid circuits at the respective ends of the system to be non-differential, the displacement of the plunger and piston being equal at their respective ends.

In Figures 12-19, we have illustrated, by diagrammatic sectional views, the relative positions of the pump B, the control valve C, and the press parts A during stated stages of operation with the cam D adjusted to the full discharge effecting position. In these figures the pump plunger operating .crank and the control valve operating cam are diagrammatically shown side by side, in-

stead of in their proper axially aligned position.

In Figure 12 the pump plunger 35 is at its lower dead center position, and the press ram piston 9 is at its upper dead center or stroke change position. The control valve is movingdownwardly and the control plugs thereof are so positioned relative to the closed circuit connections that the pump plunger is about to start sucking through 93, 94, 65, 62, and 66 from the press cylinder 8 ure 12, should the valve plug 44 prevent immediate fluid passage to the press cylinderas above described, this instant of normal circuit stoppage will be taken care of by opening of the check valve I99, which communicates directly with the upper end of the press cylinder through the conduit I08.

In Figure 13 the pump plunger operating crank is shown at a position 45 beyond lower dead center, and thus the pump plunger is moving upwardly. The press ram and the control valve are moving downwardly. In this position of the parts the movement of the pump plunger is sucking fluid through 93, 94, 65, 62, and 6 6 from the press cylinder beneath the ram piston, and is expelling pressure fluid through 5|, 55, 58, 95, and 96 to the press cylinder above the ram piston.

In Figure 14 the plunger operating crank is positioned 90 beyond lower dead center, and is causing the pump plunger to move upwardly. The press ram is being moved downwardly, and

the control valve has reached the lower limit of positioned 45 ahead of top dead center; and is moving the pump plunger upwardly. The press ram is being moved downwardly and the control valve is moving upwardly. In this position of the parts the suction communication between the pump cylinder and the press cylinder is through 93, 94, 65, 62, and 66, and the pressure communication between the pump cylinder and the press cylinder is through 5|, 55, 58, 95, and 96.

In Figure 16 the pump plunger operating crank is shown at top dead center, the press ram is at its bottom dead center or stroke change position,

and the control valve is moving upwardly. In this position of the parts suction communication between the pump cylinder and the press cylinder is about to start through 9|, 92, 56, 53, and 59, and pressure communication between these cylinders is about to be inauguratedthrough 52, 68, 53, 91, and 98 to thus cause the press ram to move upwardly. Should the control valve plug 44 fail to instantly open the pressure communication referred to,'the check valve I may open and provide communic'ationthrough the duct it directly with the lower end of the press cylinder. As pressure is built up beneath the ram piston in overcoming the-inertia of the ram and piston mass, the relief valve I I2 will open momentarily to open communication with the tank |3 through these cylinders is afforded through 52, 60, 63, 91, and 98.

In Figure 18 the plunger operating crank is positioned past top dead center, the press ram is moving upwardly, and the control valve is stationary at its highest position, and is about to descend. In this position of the parts suction communication between the pump and press cylinders is afforded through 9|, 92, 56, 53, and 59 and pressure communication between these cylinders is afforded through 52, 60, 63, 91, and 98.

In Figure 19 the plunger operating crank is positioned 45? ahead of bottom dead center, the press ram is moving upwardly, and the control valve downwardly. In this position of the parts suction communication between the pump and press cylinders is afforded through 9|, 92, 56, 53, and 59, and pressure communication between these cylinders is afforded through 52, 66, 63, 91, and 98. x Figures 20-27 are similar to Figures 12-19 and illustrate like positions of the .plunger operating crank with the control cam set to render a part only of the pump displacement effective in imparting movement to the press ram, thus providing for a less than full stroke operation of the press ram. It should be understood that in these partial output effecting settings of the cam the first portion of the pressure fluid expulsion occasioned by the travelling pump plunger is not directed against the press ram piston but is bypassed to the opposite end of the pump plunger,

thus rendering the desired portion of plunger travel ineffective. In the figures just referred to we have shown the cam set for imparting a half stroke to the ram, thus occasioning a by-passing of pressure fluid during the first half of the pump plunger stroke.

- In Figure 20 the plunger operating crank is shown in its lower dead center position, and the press ram piston at its upper dead center or stroke change position. The control valve is stationary at the lower limit of its travel and about to move upwardly. In this position of the parts, instead of acting against the upper, face of the ram piston, the displacement of the pump plunger is about to be by-passed through 5|, 54, 51, H6, H8, H9, 65, 62, and 66 from the pump cylinder above the plunger to the pump cylinder beneath the plunger; and thus initial upward movement of the pump plunger does not impart downward movement to the press ram. It will be observed that the upper displacement face of the pump plunger is larger than its lower displacement face,

and consequently more pressure fluid will be displaced by said upper face than can be accommodated in the chamber beneath the lower face. This surplus displacement may pass freely to the tank l3 through the connection I H. In the event that the control valve plug 43 does not immediately open sufficiently to accommodate the bypass communication referred to, the check valve |II9 can open momentarilyto relieve the pressure.

tank I3 through the connection H! as above stated. i

In Figure 22 the plunger operating crank is positioned 90 past lower 'dead center, the control valve is moving downwardly, and the pressure fluid being displaced by the pump plunger is about to be directed against the press ram piston to cause it to travel downwardly. The parts are now positioned for affording suction communication between the pump and press cylinders through 93, 94, 65, 62, and 66, and are about to open pressure communication between these cylinders through 5|, 55, 5 8, 95, and 96. For the instant during which the valve plug 44 may obstruct the pressure communication just referred to, the desired communication with the upper face of the ram piston may be had through the check valve I69 and conduit I08.

In Figure 23, the plunger operating crank is positioned 45" ahead of top dead center, the press ram is moving downwardly, and the control valve is moving upwardly. Suction communication between thepump and press cylinders is afforded through 93, 94, 65, 62, and 66, and pressure communication between these cylinders is afforded through 5|, 55, 58, 95, and 95.

In Figure 24 the plunger operating crank is shown at top dead center, the press ram, having completed its half stroke, is stationary at its lower adjusted dead center or stroke chan ge position, and the control valve is moving upwardly. Suction communication btween the pump and press cylinders is now had through 9|, 92, 56, 53, and 59, and pressure communication between these cylinders is about to be inaugurated through 52, 60, 63, 91, and 98. It is to be understood of course that no actual travel of the ram is taking place in view of-the dead center position of the plunger operating crank. Should the valve plug 44 fail to open the pressure communication referred to the instant demanded, the check valve HI and connection H0 can momentarily provide the desired communication. It should be understood also that, during the instant of reversing the direction of press ram travel, the built up pressure, acting to dampen the inertia force of the ram, may be relieved by a momentary blowing of the relief valve H2.

In Figure 25 the plunger operating crank is positioned 45 past top dead center, and the ram and control valve are moving upwardly. Suction communication between the pump and press cylinders is aflorded through 9|, 92, 56, 53, and'59, and pressure communication between these cylinders is had through 52, 66', 63, 91, and 98. It should be understood that, during the downward movement of the plunger, the excess fluid displacement occasioned by the previous upward travel of the plunger during the by-passing interval, and forced into the tank I3, will be returned to the circuit through H1, H6, 57, 54, and 5|. See also Figure 26.

In Figure 26 the plunger operating crank is positioned at 90 past top deadcenter, and the control valve is at the upper limit of its stroke and about to move downwardly. In this position of the parts effective suction communication between the pump and the press cylinders afforded trated in Figures 22 and 24. Therefore, by the time the pump plunger operating crank has moved to the position illustrated in Figure 26 the positioned 45 ahead of bottom dead center, the

press ram is stationary as above described, and. the control valve is moving downwardly. In this position of the parts the by-passingof fluid from the displacing to the sucking end of the pump plunger continues through 52, 60, 63, 91, 98, the press cylinder chamber beneath the ram piston, H2, H3, I3, H1, H6, 51,54,and5|.

Figures 28-35 are diagrammatic views similar to Figures 12-19 and -27, and in this series of diagrams the plunger operating crank is shown in like positions, the effects of a no-delivery con- 5 trolling position of the cam being illustrated. In Figure 28 the plunger operating crank is shown at lower dead center position, and the press ram at its upper dead center or stroke change position. The control valve is stationary at the lower limit of its travel and is about to move upwardly. In this po'sition'of the parts Icy-passing of fluid from the upper end of the pump cylinder to the lower end thereof is about to take place through 5|, 54, 51, H6, H8,- H9, 65, 62, and 66. figure and in all figures of this group illustrating the no-delivery phase of pump operation the pressure fluid is by-passed back and forth from one end of the pump cylinder to the other without any effect upon the press ram. As the plunger moves upwardly it will displace more fluid than can be accommodated in the chamber beneath the plunger and consequently an outlet must be provided for the excess displacement. This excess displacement finds its Way to-the tank I3 through 5|, 54, 51, H6, and III,

In Figure 29 the plunger operating crank is positioned at 45 past bottom dead center, the press ram remains stationary at the upper limit of its stroke, and the control valve is moving upwardly. In this particular adjustment of the parts the bypassing of the fluid is taking place through 5|, 54, 51, H0, H8, H9, 65, 62, and 66, the excess of, fluid displacement finding its way to the tank I3 through H1.

In Figure 30 the plunger operating crank is positioned 90 past'bottom dead center, the press ram remains at the 'upper limit of its stroke, and. the control valve is at the upper limit of its movement and about to move downwardly. The bypassing of fluid continues to take place through 5|, 54, 51, H6, H8, H9, 65, 62, and 66, and the excess of fluid displacement finds its way to the tank 53 through H1.

It should be understood that in this sitioned at top dead center, the ram remains stationary at the-upper limit of its stroke, and the control valve is at the lower limit of its movement and about to move upwardly. The pump plunger being stationary for the instant, no actual flow of fluid is being occasioned. The by-passing of the fluid is now about to take place through 52, 60, 63, 91, 98,.the bottom chamber of the press cylinder, H2, H3, tank I3, H1, H6, 51, 54, and SI from the bottom end of the pump cylinder to the top end thereof. Owing to the differential in displacement areas at the top and bottom of the plunger, the plunger, on its downward travel, is unable to displace fluid to fill the chamber above the plunger. It will be understood, however, that fluid necessary to relieve the tendency to partially evacuate the upper pump cylinder chamber will be supplied from the tank l3 through H1, H6, 51, 54, and 5|.

In Figure 33 the plunger operating crank is positioned 45 past top dead center, the press ram remains stationary at the upper limit of its stroke, and the control valve is moving upwardly. By-passing of fluid is now being efiected through 52, 60, 63, 91, 98, the press cylinder chamber, H2, H3, tank I3, H1, H6, 51, 54, and 5|, the necessary fluid column replenishment being provided for through tank I3, H1, H6, 51, 54, and 5|.

In Figure 34 "the plunger operating cra k is positioned 90 past top dead center, the ra remains stationary at the upper limit of its stroke, and the control valve is at the upper limit of its travel and about to descend. In the position of the parts illustrated by-passing of fluid isv effected' through 52, 60, 63, 91, 98, the press cylinder chamber, H2, H3, tank I3, H1, H6, 51, 54,

and 5 I, the necessary fluid column replenishment being provided for through tank I3, H1, H6, 51,.

54, and 5|.

In Figure the plunger operating crank is positioned ahead of bottom dead center, the ram remains stationary at the upper limit of its stroke, and the control valve is moving downwardly. In this position of the parts by-passing plunger shown displaces an amount of fluid V- at its upper or larger end and V2 at its lower or smaller end. The press ram, due to the short stroke required, will travel relatively to the plunger travel an amount inversely proportionate to their areas. This proportion follows the principle that the displacements of both plungers are equal to each otheron their respective ends, thus providing for the simplest kind of closed circuit between pump and press. I

The uni-directional flow of power fluid in eac direction to andqfrom the press makes it possible to bring about reciprocation of the press ram directly by reciprocation of the pump plunger, withoutv the need of complicated operating and pilot valve systems.

It should be understood that the press ram reciprocation lags slightly behind the pump plunger reciprocation, the amount of time lagbeing due to the compressibility of fluid in the passages. The synchronous motion between the pump plunger and the press ram cannot be upelastic compression of the short columns of fluid in the press are almost negligible, and yet are suiilcient to take care of the high speed inertia that the pressure in the system will be determined by the resistance offered by the press,

-that is, by the short period of pressing resistance at the end of the working stroke and by the weight and inertia of the ram to be brought up in the upper dead center.

As the pump plunger carries out an approximate harmonic motion, so will the press ram, due to the rotation of the pump crank at a constant speed.

In Figure 11 we have attempted .to indicate diagrammatically the differences in the stroke of the pump plunger and press ram, and also the dwell actionoccasioned in the operation of the press. In order to impart a dwell to the press ram at the end of its working stroke, the pump plunger is operated at a stroke designated M--N somewhat longer than the ram stroke indicated by XY. The time interval indicated by the sector T in Figure 11 is employed for building up maximum constant pressure which is desirable in the pressing operation' and is controlled by the adjustable high pressure relief valve H4. Similar provision is made for suitable ram return pressure by the adjustable low pressure relief valve H2. It will be understood of course that in order to take up the inertia force and reverse the direction of travel of the mass of the ram and its piston a certain amount of pressure. must be built up during a certain time interval, and the valve H2 serves to accomplish this purpose. It should be understood that the setting or adjust ment of the valves H2 and H4 is always such that the elastic cushion action of the pressure fluid can be utilized to dampen the inertia force of the ram.

The equalizing check valves IDS-l II are ordinarily kept seated by pressure in the chambers above and belowthe ram piston, and open only when the pressures in the chambers above and below the pump piston overstep the pressures in said press cylinder chambers, which happens at partial stroke operation adjustments when the pump delivers only a portion of its maximum delivery, a portion "of the fluid being by-passed for purposes hereinbefore described in detail. The valves I09 and HI will pass fluid only at partial stroke adjustments when the control valve blocks valve H4 is a high pressure relief valve set for the maximum working pressure at which the press is to operate during its actual working stroke, see Figure 11. This valve H4 will blow or relieve pressure from the point indicating the beginning of the time interval T to the center thereof. However, only a very small amount of fluid will be released which is proportional to the travel indicated by MX. In this way the relief valve H4 in the circuit of the working See for example Figure 7 stroke provides an ideal means to build up constant pressure for a certain length of time, as is desired in the operation of the press. The amount of fluid to be released by the valve is so small that the valve may need only to ease up a little against its spring, thus providing for the required increase in volume represented by the overtravel designation .M-X in Figure 11. Thus we claim that the function of this. hydraulic pressure relief valve israther of a breathing character whereby it provides a time element for building up pressure for the desired high speed press operation; It is to be noted, however, that the hydraulic system or fluid circuit does not lose fluid by reason of operation of the valve. The function of the low pressure relief valve H2 is similar, except for the part it takes in the described in connection with Figures 26, 2'7, 33, 34,

and 35; and, because it provides only for the return motion of the press ram, the pressure necessary for that cycle is low, and the valve H2 will function to blow or relieve pressure only when the inertia force of the reciprocating press ram mass is in its lower dead center position.

It should be obvious therefore that the valves I09, HI, H2, and H4 operate automatically to adapt the press for the short stroke high speed operation for which our improved press has been designed.

It should be understood that the press can be controlled by various means. In this disclosure we have shown and described a mechanical, manually set, and automatically operating control mechanism. This particular mechanism may 013.35 course be modified without departing from thescope of our invention as pointed out in the appended claims.

As hereinbefore. described, the driving motor (not shown) may be coupled directly or indirect- 40 1y with the crank shaft extension 29; and the fly wheel 30 will serve to carry over the peak load of the press and thus it is possible to use a smaller driving unit or motor than would otherwise be necessary to afford proper operation at maximum loads. I

It will be observed that the control cam is of such a character and so mounted directly upon the crank shaft that, even though shifted along its axis, its neutral position alwaysis in synchronism with the dead centers of the pump.

It should also beobserved that the valves H4 and I I2 contribute toward making the press ram a free ram capable of having its relation with the pump plunger shifted during conditions of opera- 65 tion. For example, it is possible for the press ram to engage work and be stopped thereby in advance of the end of its normal stroke, the pressure thus built up being relieved through the valve H4. The ram, being thus displaced from its normal relation with the plunger, will start "to move from its advanced position when the pressure fluid is applied beneath the same in the manner hereinbefore described, and thus, on its return stroke, the ram will reach its upper limit much earlier than would ordinarily be the case, and will be stopped by engagement with the upper endof the press cylinder. The pressure built up due to the continuation of the pump plunger stroke while the press ram is stationary can be relieved by the valve 1 l2, and the ram may thus be returned to its normal relation with the pump plunger.

In the foregoing description we have disclosed a novel form of hydraulic press in which the following advantages are present in addition to those hereinbefore referred to and otherwise obvious:

(a) The direct connection of a press with a double acting reciprocating plunger pump or its equivalent.

(b) The provision in a press of the character stated of uni-flow passages for the working fluid during the working stroke as Well as for the reverse stroke of the press ram.

(0) The provision of a press of the character stated in which simultaneous and synchronous reciprocation of the hydraulic pump and the press ram is provided for.

(d) The provision of a press of the character stated in which the control of the starting and stopping is provided for direct from the pump driving shaft.

(e) The provision in a press of the character stated of means affording direct connection with the shaft of the prime mover of a hydraulically balanced and mechanically driven by-pass eifecting valve in order to obtain a variable stroke in the press.

(f) The provision in a press of the character stated 'of means whereby the control of the reversing of the direction of travel of the high speed ram is provided for by action of the pressure fluid without the introduction of a special reversing valve or valve system.

(9) The provision in a press of the character stated of a double acting varied-contoured cam. mounted on the shaft of the prime mover or pump and capable of controlling the stroke of the press While the prime mover or pump is running.

(h) The employment in a press of the char-- acter stated of a long stroke small area plunger driving a short stroke large area press ram, thereby enabling the connection of the small area plunger with a moderate size of crank shaft, and the employment of a small size motor or driving unit, and providing for the convenient building up of high tonnage in the press operation.

(2') The hydraulic adjustment of the stroke of the press ram by employment of a varied-contoured cam in order to build up operating pressure over the desired time interval at the end of the working stroke or at the so-called dead center or stroke change position of the ram. This adjustment is positive, and permits the application of working pressureduring the desired time interval to exert a squeezing pressure on. the work.

(7) The provision in a press of the character stated of means for providing direct communication, during short stroke by-passing delivery, be-' tween the pump cylinder and the press cylinder through the pressure equalizing check valve so as to prevent trapping of oil by the by-pass control.

'(k) The direct connection of a high speed press ram with a high speed plunger pump in which means is provided for utilizing the compressibility of the fluid to allow considerable margin for the taking up of the inertia forces of the reciprocating masses. It is notable that, in the system herein disclosed, the plungers are still in their dead centers and communication closed when the kinetic energy of the press ram has to change its motion for the reverse stroke. The elastic fluid, being more or less positively closed in the pump and press chambers, will exert a reaction on the ram, as it starts to reverse its direction, due to the harmonic motion of the pump plunger and the ram piston, and the ram piston stops for an instant at the dead center or stroke change position. In ordinary valve controlled presses, the reversing valve opens suddenly, either too early or too late, and thus the system cannot regain the kinetic energy of the 5 .plunger forcontrolling the operation of the press and building up working pressure therein.

(0) The employment in a press of the character stated of a control valve cooperating with a 20 reciprocating pump and a hydraulic press in controlling the starting, the stopping, and press stroke variation, and the time element adjustment for the duration of working pressure during the actual working period.

From the foregoing description taken in connection with the accompanying drawings it is thought that the novel details of. construction, the manner of use, and the advantages of our, invention will be readily apparent to those skilled 30 in the art to which it relates.

We claim:

1. In a hydraulic press, the combination of a double acting reciprocating ram, a double acting reciprocating plunger pump, a closed hydraulic 35 pressure circuit connecting the pump and ram in, cooperative relation whereby each stroke of the pump plunger will impart a stroke to the ram, and valve means operated in timed relation with said pump plunger and being adjustableto bypass a portion of the displacement of the pump plunger to vary the length of strokes imparted to the ram by the plunger. v

2. In a hydraulic press, the combination of a double acting reciprocating ram, a double acting cooperative relation whereby each stroke ofthe pump plunger will impart a stroke to the ram, and means to vary the stroke imparted to the ram by each pump plunger stroke, said means including by-passingducts connected in said circuit,

a control valve connected in the circuit for controlling said ducts, and a valve actuating cam operatively connected withsaid valve and being operated in timed relation with the pump.

3. In a hydraulic press, the combination of a double acting reciprocating ram, a double acting reciprocating plunger pump, and a closed hydraulic pressure circuit connecting the pump and ram in cooperative relation whereby each stroke of the pump plunger will impart a stroke to the ram, said pump including a crank shaft and connections for imparting reciprocations to the plunger, and means including by-passing ducts 5 connected in said circuit, a control valve connected in the circuit for controlling said ducts, anda valve actuating cam operatively connected With said cam and being operated in timed rela tion with the pump and adjustable to vary operram in cooperative relation whereby each stroke of the pump plunger will impart a stroke to the ram, said pump including a crank shaft and con nections for imparting reciprocations to the plunger, a flyv wheel on the crank shaft, and means including by-passing ducts connected in said circuit, a control valve connected in the circuit for controlling said ducts, and an adjustably positioned varied-contoured valve actuating cam mounted to rotate with the crank shaft and adjustable to variably control the actuation of the control valve.

5. In a hydraulic press,,the combination of a double acting reciprocating ram, a double acting reciprocating plunger pump, a closed hydraulic pressure circuit connecting the pump and. ram in cooperative relation whereby each stroke of the pump plunger will impart a stroke to the ram, and means including bypassing ducts connected in said circuit, a control valve connected in the circuit for controlling said ducts, and a shiftable valve actuating cam operatively connected with said valve and having provision when in one position for actuating the valve to effect a full discharge of the pump, in another position for ac-.

tuating the valve to effect a no-delivery condition of' the pump, and at other positions for actuating the valve to efiect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram.

6. In a hydraulic press, the combination of a double acting reciprocating ram, a double acting reciprocating plunger pump, a closed hydraulic pressure circuit connecting the pump and ram in cooperative relation whereby each stroke of the pump plunger will impart a stroke to the ram, means including by-passiug ducts connect ed in said circuit, a control valve connected in the circuit for controlling said ducts, and a shiftable valve actuating cam operatively connected to said valve and having provision when in one position for actuating the valve toefiect a full discharge of the pump, in another position for actuating the valve to eiTect a no-delivery condition of the pump, and at other positions for actuating the valve to eflect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram, and means acting automatically to stop the press with the cam in position for actuating the valve to effect a no-delivery condition of the pump.

7. In a hydraulic press, the combination of a double acting reciprocating ram, a double acting reciprocating plunger pump, a closed hydraulic pressure circuit connecting the pump and ram in cooperative relation whereby each stroke of the pump plunger will impart a stroke to theram, means including bypassing ducts connected in said circuit, a control valve connected in the circuit for controlling said ducts, and a shiftable valve actuating cam operatively connected with said valve and having provision when in one position for actuating the valve to eiiect a full discharge of the pump, in another position for actuating the valve to effect a no-delivery condition of the pump, and at other positions for actuating the valve to effect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram, and means acting automatically to stop the press with the cam in position for actuating the valve to efiect a no-delivery condition of the pump and including a recessed block movable with the press ram, a member' movable with the cam and adapted to enter the block recess, means to urge the cam and member toward the block, and releasable means normally active to hold the cam against movement toward the block.

8. In a hydraulic press, the combination of a double-acting reciprocatingram, a double acting 5 reciprocating plunger pump, a closed hydraulic pressure circuit connecting the pump and ram in cooperative relation whereby each stroke of the pump plunger will impart a stroke to the ram, means including by-passing ducts connected in said circuit, a control valve connected in the circuit for controlling said ducts, and a shiftable valve actuating cam operatively connected with said valve and having provision when in one position for actuating the valve to effect a full discharge of the pump, in another position for actuating the valve to effect a no-delivery condition of the pump, and at other positions for actuating the valve to effect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram, and means acting automatically to stop the press with the cam in position for actuating the valve to effect a nodelivery condition of the pump, the displacement of the upper ends of the plunger and ram being equal and the displacement of the lower ends of the plunger and ram being equal to provide for perfect balance in the circuit during full discharge operation of the pump.

9. In a hydraulic press, the combination of a double acting reciprocating ram, a reciprocating plunger pump, a closed hydraulic pressure circuit connecting the pump and ram in cooperative relation whereby each stroke of the pump will impart a stroke to the ram, and valve means operated in timed relation with said pump plung er, said valve means being adapted to automatically by-pass a portion of the displacement of the pump and thus control the length of stroke imparted to the ram. 40

10. In a hydraulic press, the'combination' of a reciprocating ram, a hydraulic pressure circuit,

a pump for forcing pressure fluid through the circuit for moving the ram, and control means for controlling the flow of fluid and including a reciprocable control valve, and a shiftable valve actuating cam having provision when in one position for actuating the valve to effect a full discharge of the pump, in another position for actuating the valve to effect a no-delivery condition of the pump, and at other positions for actuating the valve to effect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram.

11. In a hydraulic press, the combination of a reciprocating ram, a hydraulic pressure circuit,

a pump for forcing pressure fluid through the. circuit for moving the ram, control means for controlling the flow of fluid and including a reciprocable control valve, and a shiftable valve 6 actuating cam having provision when in one position for actuating the valve to efiect a full discharge of the pump, in another position for actuating the valve to effect a no-delivery condition of the pump, and at other positions for actuating the valve to effect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram, and means acting automatically to stop the press with the cam in position for actuating the valve to efiect a no-delivery condition of the pump.

12. In a hydraulic press, the combination of a reciprocating ram, a hydraulic pressure circuit, a, pump for forcing pressure fluid through the circuit for moving the ram, control means for controlling the flow of fluid and including a reciprocable control valve, and a shiftable valve actuating cam having provision when in one position for actuating the valve to effect a full discharge of the pump, in another position for actuating the valve to effect a no-delivery condition of the pump, -and at other positions for actuating the valve to effect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram, means acting automatically to stop the press with the cam in position for actuating the valve to effect a no-delivery condition of the pump and in eluding a recessed block movable with the press ram, a member movable with the cam'and adapted to enter the block recess, means to urge the cam and member toward the block, and releasable means normally active to hold the cam against movement toward the block.

13. In a hydraulic press, the combination with l the press ram, the hydraulic circuit, and the pressure fluid circulating pump, of ram travel control means comprising a fluid flow control valve, a shiftable valve actuating cam having provision when in one position for actuating the valve to efiect a full discharge of the pump, in another position for actuating the valve to effect a nodelivery condition of the pump, and at other positions for actuating the valve to effect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram, means tending to force the cam toward the no-delivery effecting position, a cam holding lever in yielding abutment with which the last named means holds the cam, and releasable means for securing the lever in position forming a fixed abutment for the cam.

14. In a hydraulic press, the combination with ward the no-d elivery effecting position, a cam holding lever in yielding abutment with which the last named means holds the cam, adjustable means for determining the position in which the lever forms a fixed abutment for the cam, and means for moving the lever away from abutting relation with the cam to enable movement of the cam toward the no-delivery eirecting position 1 thereof.

15. In a hydraulic press, the combination with the pressram, the hydraulic circuit, and the prestrol means comprising a fluid flow control valve, a shiftablevalve actuating cam having provision when in one position for actuating the valve to effect a full discharge of the pump, in another position for actuating the valve to effect a nodelivery condition of the pump, and at other positions for actuating the valve to effect various degrees of discharge of the pump, thereby controlling the effect of the pump upon the press ram, means tending" to'force the cam toward the nodelivery effecting position, a cam holding lever in yielding abutment with which the last named means holds the cam, adjustable means for determining the position in which thelever forms a fixed abutment for the cam, a recessed block movable with the press ram, a stop pin movable with the'cam, and means for moving the lever away from abuttingrelation with the cam to enable movement of the cam to its no -delivery effecting position and of the stop pin into the recess in said block for causing press operation to stop with the ram in a fixed position determined by engagement of the stop pin in the block recess.

16. In a hydraulic press, the combination of a reciprocating ram, a hydraulic pressure circuit, a pump for forcing pressure fluid through the c'ir cuit for moving the ram and including a pump shaft, control means for controlling the flow of fluid and including a reciprocable control valve, and a shiftable valve actuatingcam having provision when in one position for actuating the valve to effect a full discharge of the pump, in another position for actuating the valve to effect a no-delivery condition of the pump, and at other positions for actuating the valve to eifect various degrees of discharge of the pump, thereby controlling the eifect of the pump upon the press 'ram, and stop means adapted to positively prevent movementof said ram, said control means and said stop means being supported directly on said pump shaft.

17. In a hydraulic press, the combination of a double acting short stroke large area reciprocating ram, a double acting long stroke small area sides of the pump plunger respectively and active at times when the ram stroke is being by-pass controlled to prevent trapping of pressure fluid in the circuit adjacent the associated sides of the plunger.

18. In a hydraulic press, the combination of a double acting reciprocating ram, a reciprocating plunger pump, a closed hydraulic pressure circuit connecting the pump and ram in cooperative relation whereby each stroke of the pump will impart a stroke to the ram, valve means operated in timed relation with said pump plunger, said val means being adapted to automatically by-pass a portion of the displacement of the pump and thus control the length of stroke imparted tothe ram, and relief valves controlling the building up of a predetermined pressure at each change stroke or dead center ram position and also for trapping the pressure fluid ahead of the ram at each 7 change stroke or dead center position thereof to enable the compressibility of the entrapped fluid to exert a cushioning reaction whereby to facilitate the taking up of inertia forces of the ram mass. v

19. In a hydraulic press, the combination of a double acting reciprocating ram, a reciprocating plunger pump, a closed hydraulic pressure circuit connecting the pump and ram in cooperative relation whereby each stroke of the pump will impart a stroke to the ram, valve means operated in timed relation with said pump plunger, said valve

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