US2312213A

US2312213A - Hydraulic press

Info

Publication number: US2312213A
Authority: US
Inventors: Ferris Walter
Original assignee: Oilgear Co
Current assignee: Oilgear Co
Priority date: 1941-06-18
Filing date: 1941-06-18
Publication date: 1943-02-23
Anticipated expiration: 1960-02-23

Description

Feb. 23, 1943.

w. FERRls 2,312,213

HYDRAULIC PRES S Filed June 18, 1941 2 Sheets-Sheet 1 2 BY l MENOR/vm. l

Feb. .23,v 1943. w. FERRls HYDRAULIC PRESS Filed June 18, 1941 2 Sheets-Sheet 2 Hm y @5 m M a/ H a. a lo 2m ,l d Mu l 9s 5 M4 .S .HH mm MF WR E T .L w

TTORNEY.

.W, .g m

Patented Feb. 23, 1943 HYDRAULIC PRESS waiter Ferns, Milwaukee, wis., assigner to The Oilgear Company, Milwaukee, Wis., a corporation of Wisconsin Application June 18, 1941, Serlal No. 398,521

21 Claims.

This application is a continuation in part of and a substitute for application Serial No. 304,893 filed November 17, 1939. The invention relates to a bending brake or other hydraulic press which is so wide that a plurality of' motors are required to advance and retract the bending beam or platen thereof.

An object of the invention is to provide a hydraulic press in which the beam or platen is operated by a plurality of hydraulic motors and the motors are synchronized to thereby cause both ends of the beam vto move upward or downward at the same adjustable speed and to maintain their relative positions when the beam presses against a stationary die or work piece which is located nearer to one end of the beam than to the other end thereof.

Another object is to provide a hydraulic press in which the beam or platen is operated by a plurality of hydraulic motors, the beam or platen may be initially adjusted at an angle to the head or bed of the press, and the motors are synchronized to thereby cause both ends of the beam or platen to move in synchronism and the beam or platen t0 remain at the adjusted angle throughout the stroke of the press.

Other objects and advantages will appear from the description hereinafter given of a hydraulic press in which the invention is embodied.

According to the invention in its general aspect, a hydraulic press has its beam or platen operated by two hydraulic motors which are connected thereto at or near opposite ends thereof, each motor is energized by liquid supplied thereto by a variable displacement pump, means are provided for regulating the pumps to thereby cause the motors to move the beam or platen, and means are provided for regulating one or both pumps in response to a variation in the movement of one end of the beam or platen relative to the movement of the other end thereof to thereby correct the variation in speed.

According to the invention in another aspect, the beam or platen is connected to the motors by pivotal connections whereby it may be adjusted either at an angle or parallel to the head or bed of the press. s

The invention is exemplied by the bending brake shown schematically in the accompanying drawings in which the views are as follows:

- bending brake but it is to be understood that the invention may as readily be embodied in other types of presses and that the presses may be either manually or automatically controlled.

Figs. 1-3

As shown, the bending brake is provided with a bed or base l having a bed plate or die holder 2 arranged thereon and two

columns

3 and 3* xed thereto at opposite ends thereof.

Columns

3 and 3* have two shoes 4 and I fitted thereon, respectively, and connected by rods 5 and .'ia to

pistons

8 and 3 which are fitted, respectively, in cylinders I and 'Iu carried by

columns

3 and 3 respectively, each cylinder forming with its piston and the rod thereof a hydraulic motor for sliding a,

shoe

4 or 4 vertically upon a column 3 or 3B.

Shoes t and 4B are biiurcated and support a bending beam or platen 8 which has one end thereof arranged within shoe 4 and journaled upon' a pin 9 carried thereby. The other end of beam 3 is arranged within shoe 4 and has' a rectangular slot ill formed therein to receive a slide il which is connected to shoe by a pin 9B and bears against the upper and lower edges l of slot I0 but is movable longitudinally thereof.

Fig. l is a diagrammatic view showing the relation of the several parts and the hydraulic circuit of the machine.

Fig. 2 is a sectional plan view taken on the line 2-2 of Fig.. 1 and showing the pivotal con- The arrangement is such `that any movement or force transmitted to shoe Il by motor 6-1 will be transmitted through pin 9 to one .end of beam 3, and any movement or force transmitted to shoe 4a by motor -'l will be transmitted through pin 9 and slide il to the other end of beam 8. When one end of beam 8 is raisedor lowered relative to the other end thereof, the ends of beam 8 wil1 pivot upon

pins

3 and 3", respectively, and slide I I will move longitudinally of slot I0.

Liquid for energizing motor 6-1 is supplied thereto by a reversible pump I2 which has its opposite sides connected to opposite endsy of cylinder i by channels I3 and i4 respectively. Liquid for energizing motor SSL-1 is` supplied thereto by a reversible pump I2 which has its I in Patent No. 2,114,005. such a pump has a displacement varying member or slide block which is shiftable in one direction or the other from a central or neutral position to cause the pump to deliver liquid in a direction and at a rate determined by the direction and the distance the slide block is offset from its neutral position. When the slide block is in its neutral position, the pump will be at zero stroke and no liquid will be delivered thereby. The slide block is ordinarily shifted by hydraulic actuators under the control of a rotary follow-up valve as shown in said patent but, in order that the valve and its operating mechanism may appear in the same plane, each slide block has been shown as being adapted to be shifted by ordinary hydraulic servo-motors under the control of a reciprocating valve which is connected by means of a follow-up mechanism to its actuator and to the slide block.

As shown, pump I2 is provided with a slide block I5 which is adapted to be shifted toward the left, or in a direction to cause pump I2 to discharge liquid into channel I3, by a piston I6 which is connected thereto or in contact therewith and fitted in a cylinder I1 carried by the pump casing. Slide block I5 is adapted to be shifted toward the right, or in a direction to cause pump I2 to discharge liquid into channel I4, by a piston I8 which is connected thereto or in contact therewith and fitted in a cylinder I9 carried by the pump casing, the eiective pressure area of piston I8 being considerably greater than that of piston I8.

Liquid for operating servo-motors I6I1 and I8-I9 is supplied by a gear pump 20 which is ordinarily driven in unison with pump I2 and arranged in the casing thereof according to the usual practice but which has been shown as being separate therefrom. Also, gear pump 20 has been shown as providing liquid for energizing the servo-motors of both of pumps I2 and I2 but each of those pumps may have a gear pump for energizing its servo-motor.

As shown, gear pump 20 draws liquid from a reservoir 2I and discharges it into a branched supply channel 22 having one of its branches connected to cylinder I1 so that piston I6 constantly tends to shift slide block I5 toward the left.

The liquid discharged by gear pump 20 in excess of requirements is exhausted into reservoir 2I through a relief valve 23 which is connected to channel 22 and enables gear pump 20 to maintain therein a uniform pressure great enough to enable piston I6 to exert a force considerably in excess of the force required to shift slide block I5 toward the left when cylinder I9 is open to drain and to enable piston I8 to exert a force considerably in excess of the force required to shift slide block I5 toward the right against the resistance of piston I6 when cylinder I9'is open to supply channel 22.

The flow of liquid to and from cylinder I9 is under the control of a valve 24 which is tted in the bore of a valve casing 25 having three annular grooves or

ports

26, 21 and '28 formed therein. Port 26 and the right end of valve casing 25 are connected to a drain channel 29, port 21 is connected to cylinder I9 by channel 39 and port 28 has a branch of supply channel 22 connected thereto.

Control valve 24 has been shown as having its center piston of exactly the same width as port 21 so that, when valve 24 is in its central or neutral position, the center piston of valve 24 blocks port 21 and its edges make a line and line contact with the edges of port 21. Blocking port 21 prevents liquid from flowing to or escaping from cylinder I9 so that slide block I5 is held stationary against the force exerted thereon by piston I6. When valve 24 is shifted toward the left, liquid from gear pump may flow through channel 22, valve casing and channel 30 to cylinder I9 and cause piston I8 to move slide block I5 toward the right. When valve 24 is shifted toward the right, liquid may escape from cylinder I9 through channel 30 and valve casing 25 into drain channel 29, thereby permitting servo-motor lli-I1 to move slide block I5 toward the left.

. In practice however, such a control valve ordinarily has a center piston which is slightly narrower than the port which it controls but the difference between the width of the piston and the width ofthe port is so slight that it cannot be shown in the drawings. If the center piston is slightlynarrower than port 21, its edges will be equally spaced from the edges of port 21 when valve 24 is in its neutral position, thereby permitting liquid to ilow from channel 22 into port 21 and liquid to flow from port 21 into drain channel 29 at the same rate so that there is no flow to or from cylinder I9.

The advantage of such a construction is that, if the valve piston and the port are the same width, a given movement of the valve will uncover the port the same amount while, if the piston is narrower than the port and the valve is moved a distance equal to one half the difference between the width of the piston and the width of the port, the port will be uncovered by an amount equal to twice the distance that the valve was moved so that liquid is directed to or permitted to escape from the stroke adjusting servo-motor at a rate twice as great as the rate would be if the piston and port were of the same width.

Pump I2a has been shown as being of the same type as pump I2 and as being controlled by the same kind of a valve so that a description thereof is unnecessary, corresponding parts being indicated by corresponding reference numerals with the exponent a added to the reference numerals applied to pump I2 and its valve.

Valves 24 and 24a are both actuated manually to start, reverse or to change the speed of the press and are then automatically adjusted in response to the movement of one end of beam 8 varying relative to the movement of the other end of beam 8 as reected through a three legged differential 3I which will be presently described. Diierential 3| has its first and second legs driven, respectively, from opposite ends of beam 8 and its third leg connected to a lever 32 which is normally stationary but which will swing upon its pivot in response to one end of beam 8 moving relative to the other end thereof. For example, if beam 8 is initially adjusted parallel to bed plate 2, any departure of beam 8 from parallelism therewith will cause lever 32 to swing upon its pivot.

As shown, valves 24 and 243L are adjusted manually by means of a pedal 33 arranged upon one end of a. lever 34 which is pivoted intermediate its ends upon a stationary bracket 35. 'I'he other end of lever 34 is connected by a rod 39 to the horizontal arm of a bell crank lever 31 which is pivoted upon a stationary pin 38. The vertical arm of lever 31 is connected to the lower end of a floating lever 38 which is'pivoted intermediate its ends upon a pin 48 carried by a rod 4| which is movable with slide block |6. In order to simplify the view, rod 4| has been shown attached to piston I3' but in practice such a rod is extended through the wall of the pump casing and attached directly to slide block I6.

'I'he upper end of lever 3 3 is connected by a link 42 to a floating lever 43 intermediate the ends thereof. Lever 43 has its lower end connected to the stem of valve' 24* and its upper end connected to differential lever 32 by a disconnectible mechanism comprising a rocker 44 having its upper end pivoted upon a pin 45 carried by a stationary support 46 and its lower end provided with a notch 41 which is normally in alinement with a hole 46 formed in support 46, a link 43 which connects the upper endl of lever 43 to rocker 44, and a link 56 which connects lever 32 to rocker 44 by means of pins 5| and 52 respectively. l

Pin 52 may be removed from the end of link 66 and inserted through notch 41 into hole 48, to hold rocker 44 and the upper end of lever 43 stationary, and link 58 may then be supported upon a flange 53 on support 46 so that it may slide thereon when differential 3| operates as will presently be explained.

' each other. Gear 12 has its internal teeth in is connected by a link 58 to the lower end of a lever 53 which is connected intermediate its ends to valve 24 by a link 60 and has its upper end pivoted upon pin 5|.

In order to simplify the drawing, the levers of the mechanism for shifting

valves

24 and 21|*L have been shown out of proportion and connected by closely fitted pin joints but it is to be understood that the levers are properly proportioned and that means. such as a pin and slot connec` Iit will be engaged by arm 6| when beam 8 approaches the limit of its up stroke. Collar 62 is held against arm 6| when the machine is idle by rod 36 being continuously urged downward in any suitable manner such as by means of a spring 63 arranged beneath foot lever 34.

Differential 3| (Figs. l and 3) is provided with a stationary shaft 64 which is arranged in a suitable housing (not shown) and has lever 32 pivoted thereon. The upper end of lever 3| carries a stub shaft 65 having a planet pinion 66 journaled thereon and in mesh with a sun gear 61 which is fixed upon a sleeve 68 journaled upon shaft 64. Sleeve 68 has a bevel pinion 69 fixed thereto or formed integral therewith and in mesh with abevel pinion 1||l which is fixed upon one end of a horizontal shaft 1|.

Sleeve 66 has journaled thereon a` compound nesn with the teem of planet pinion so and its external teeth in mesh with the teeth of a bevel pinion 13 which is fixed upon one end of a horizontal shaft 1|".

The several parts of differential 3| are so proportioned that, when shafts 1| and 1|* are rotated at the same speed in the same direction gears 61 and 12 will transmit rotary motion to planet pinion 66 at the same rate, so that shaft 3l remains stationary and transmits no motion to lever 32 but, when one shaft 1| or 1|* rotates faster than the other, gears 61 and 12 will transmit rotary motion to pinion 66 at diieren't rates and thereby cause it to travel around sun gear 61 in one direction or the other and swing lever 32 in one direction or the other.

shaft 1| is Journaled in suitable bearings and connected through intermeshing

bevel gears

16 and 16 to the upper end of a vertical shaft 11 which is provided at its lower end with a bevel pinion 18 and journaled near its lower end in a stationary bearing bracket 18 shown as being carried by cylinder 1. Pinion 18 meshes with a bevel gear fixed upon one end ofa shaft 8| which is journaled in bracket 19 and has a spur pinion 82 fixed upon its other end. Pinion 82 meshes with a vertical rack 83 which is movable vertically with the right end of beam 8 as by being attached to shoe 4.

The mechanism for transmitting motion from the left end of beam 8 to shaft 1|8L may be exactly the same as but opposite hand to the above described mechanism for transmitting motion from the-right end of beam 8 to shaft 1| but it has been'shown provided with means for enabling one end of beam 8 to be moved relative to the other end thereof.

As shown, shaft 1| is connected through bevel gears 15a and 16B to the upper end of a shaft 'Ila having the lower end thereof journaled in a bearing bracket 19*L and provided with a bevel pinion 18"l which meshes with a bevel gear 80 fixed upon one end of a shaft 8|n having a pinion 82 fixed upon the other endr thereof and meshing with a rack 83*1L carried by shoe 4'.

It will be obvious that the above described mechanisms will cause shafts 1| and 1|* to be rotated in one direction in response to upward movement of beam 8 and cause shafts 1| and 1| to be rotated in the opposite direction in response to downward movement of beam 8.

Since the slack or lost motion inherent in all gear trains would prevent pumps i2 and |29 from being accurately controlled, lever 32 is constantly urged in one direction by a spring 84 `having suflicient strength to keep all lost motion out of differential 3| and the gearing and linkage connected thereto. Also, the ratios of the gearing and linkage are such that a micrometric movement of one end of beam 8 relative to the other end thereof will cause a substantial movement of control valves 24 and 24a.

In order that beam 8 may be adjusted either parallel to base I or at an angle thereto, shaft 'l1a is divided into two sections which are normally connected to each other by a separable coupling 85, the upper section of shaft 'l1l extends through an arm 86 carried by bearing bracket 19a, and a set screw 81 is threaded into arm 86 and adapted to be advanced into contact with the upper section of shaft 11* to prevent it from rotating when coupling 85 is disengaged.

Operation and pumps I2 and I2* will deliver just enough liquid to prevent beam 8 from descending.

To start the press, pedal 33 is depressed to rock lever 34 upon bracket 35 and cause 'rod 36 to rock lever 31 upon pin 38 in a counterclockwise direction.l Lever 31 will move link 54 and the lower ends of

levers

39 and 55 toward the left to cause levers 39 a'nd 55 to pivot upon pins 48 and 56 respectively. The upper end of lever 39 and link 42 will move toward the right and cause lever 43 to pivot upon the end of link 49 and shift valve 24* toward the right. The upper end of lever` 55 and link 58 will swing lever 59 upon pin 5.I Ito cause link 88 to shift valve 24 .toward the right.

leftso that

valves

24 and 24* are returned to their neutral positions substantially as soon as movement of pedal 33 ceases at which time slide blocks I5 and I5* will each have moved through a distance proportional to the distance through which pedal 33 was moved.

The liquid discharged by pumps I2 and I2* will flow through channels I3 and I3, respectively, to the upper ends of cylinders 1 and 1* and cause

pistons

8 and 8* to move beam 8 downward and thereby cause shafts 1I and 1I* to be rotated due to

pinions

82 and 82* being rotated by

racks

83 and 83* which move downward with beam 8. d u

As lonar as both ends of beam 8 move downward at the same speed, shafts 1I and 1I* will be rotatedv at the same speed and cause planet pinion 86 to rotate on a stationary axis so that no motion is imparted to'valves 24 and 24,

However, if the right end of beam 8 should "tart to run ahead of the left end thereof, shaft 1I would start to rotate faster than shaft 1I* and thereby cause planet pinion 86 to start to move around sun gear 61 in a clockwise direction as viewed in Fig. 1. Planet pinion 68 would swing lever 32 upon shaft 84 and cause it to shift valvfa 24 toward the left so that liquid from channel 22 would flow through valve casing 25 to cylinder I9 and move slide block I5 toward the right to reduce the displacement and volumetric delivery of pump I2 and thereby reduce the speed of the right end of beam 8. At thesame time, lever 32 and link 58 would swing rocker 44 upon pin 45 and cause link 49 to move the upper end of to catch up with the right end thereof at which time movement of lever 32 would cease and the follow-up mechanism would have returned

valves

24 and 24* to their neutral positions and .beam 8 would continue downward at the adjusted speed. f

If the right end of beam 8 should start to las behind the left end thereof, the control mechanism would operate in the above describedI manner but in the opposite direction to correct the variation in the movements of the two ends of beam 8. That is, as soon as' the right end of beam 8 started to lag behind the left end thereof, shaft 1I would start to rotate slower than shaft 1I* and thereby cause planet pinion 88 to start to move around sun gear 81 in a counterclockwise direction as viewed in Fig. 1. Planet pinion 88 would swing lever 32 upon shaft 84 and cause valve 24 to be shifted toward the right and valve 24* to be shifted toward the left to increase the displacement of pump I2 and the speed. of motor 6-1 and to decrease the displacement of pump I2* and the speed of motor 8*-1* until the two ends of beam 8 were even and moving at the same speed.

When the down stroke of beam 8 has been completed, pedal 33 is released to permit control rod 38 to descend and cause

valves

24 and 24* to be shifted toward the left from their neutral positions so that liquid from channel 22 can enter eylindersIS and I9* and cause pistons I8 and I8* to shift slide blocks I5 and I5* toward the right beyond their neutral positions and thereby cause pumps I2 and I2* to discharge liquid into channels I4 and I4* respectively.

As' slide blocks I5 vand I5* vmove toward the right, rods 4I and 51 move with them and swing the upper ends of

levers

39 and 55 toward the right so that

valves

The liquid discharged by pumps I2 and |27 will flow through channels I4 and I4*, respectively, to the lower ends of cylinders 1 and 1a and

cause pistons

8 and 8*)to move beam 8 upward and thereby cause shafts 1I and 1I* to be rotated in the previously described manner but in the opposite direction.

As long as both ends of beam 8 move upward at the same speed, shafts 1I and 1I*l will be rotated at the same speed and cause planet pinion 86 to rotate on a stationary axis so that no motion is imparted to valves 24 and- 24* but, if ,the right endof beam 8 should tend to lag behind or move ahead of the left end thereof, any material movement of one end of beam 8 relative vto the other end thereof would be prevented by ldifferential 3| and the associated parts which would operate as explained above.

When beam 8 approaches the limit of its up stroke, arm 8| on shoe 4* engages collar 62 and raises control rod 38 which will shift

valves

24 and 24* toward the right to cause slide blocks I5 and I5* to move toward the left until pumps I2 and I2* are at zero stroke at which time upward movement of beam 8 ceases and rods 4I and 51 will have returned valves 24* and 24 to their neutral positions. 1 v

If pin 52 is removedto disconnect lever 32 from valve 24*, link 50 lowered upon flange 53 on which it may slide when Idifferential 32 operates, and pin 52 is inserted through notch 41 into hole 48 to hold rocker 44- and the upper end of lever 43 stationary, the press will operate in the above described manner 'except that valve. 24* will be f center, or placed on the left side only of said center but, if the work were arranged at the right side only of its center and beam 8 should be pressed against the work until motor 6--1 stalled, motor 6*-1 would continue tol move the left end of beam 8 downward until stopped by the operator or until it stalled.

Since there is no assurance that short pieces of work would always be placed, either symmetrlcally about the center or under the left half of beam 8, both of valves 24 and 24EL are operated by differential 3| as explained above.

It is sometimes desired to bend a work piece a.

greater amount at one side or end than at the othervside or endl thereof. Instead of providing special dies fory this purpose as is customary, beam 8 may be adjusted at an angle to bed I so that ordinary straight dies may be employed.

Adjustment of beam 8 to any desired angle maybe accomplished by removing pin 52 *and permitting link 50 to be supported upon flange 53, inserting pin'52 through notch 41 into hole` 48 to hold rocker 44 stationary, advancing set screw 81 into engagement with the upper section of shaft 11a to prevent it from being rotated, then disengaging clutch 85, and then depressing pedal K`33 slightly to cause motors 8-51 reduced to zero so that motor 6-1 will hold the right end of beam 8 stationary.

When the left end of beam 8 has been lowered to the desired point, pedal 33 is returned to its neutral position to stop further downward movement of the left end of beam 8, collar 62 is moved downward into contact with arm 6I, clutch 85 is re-engaged, set screw 81 is retracted out of con.-

bed l or inclined in one direction or the other,

the press will operate in the above described manner and both ends of beam 8 will be moved through the same distance during both the down stroke and theup stroke of beam 8.

asis

Fig. 4

The machine may be employed to operate upon work which does not require that its beam or platen be maintained parallel to the bed or at .a predetermined angle thereto, that is; one end of the beam or, platen may advance slightly ahead of the other end without affecting the quality of the work.

In such a case, it is not necessary to start both the motors simultaneously by shifting the slide block of both pumps simultaneously when initiating a stroke of the beam or platen. It is only necessary to start one motor and cause the other motor to follow it.

This may be accomplished by omitting disconnecting mechanism 44-53 and connecting 'link 42 directly to the stemv of valve 24, and omitting link 54 and pivoting the lower end of lever 55 upon a stationary pin asA shown in Fig. 4. Then when pedal 33 is depressed, motor 6-1 will start to move the left end of beam 8 downward in the previously described mannerbut. as soon as the left end of beam 8 starts to move, gear train '151---83a will rotate shaft 1I and thereby cause differential 3| to shift pilot valve 24 which will cause slide block |5`of pump |2 to beshifted so that pump I2 will deliver liquid to motor 6-1. and cause it to move the right end of beam 8 downward as previously explained. Due to the very large ratio between gear 15* and rack 83a, the lower end of beam 8 need only a small fraction of an inch to effect operation of motor 6-1.

The machine will operate in exactly the same manner as the machine shown in Fig. 1 except that one motor starts and theA other motor-follows it instead of the motors starting simultaneously. This results in slight departures from parallelism between the various positions of the beam.

The press described herein is susceptible of various other modifications and adaptations without departing from the scope of the invention which is hereby claimed as follows:

l. The combination, with a plurality ofI reciprocating hydraulic motors, of an equal number of reversible pumps each hydraulically connected to one of said motors and having hydraulic means A for varying its displacement and a valve for controlling said hydraulic means `to thereby control the pump, means for supplying liquid through said valves to said hydraulic means, means for shifting said valves in one direction or the other simultaneously to cause said pumps to deliver liquid to one end or the other of said motors and thereby cause said motors to operate simultaneously in one direction or the other, and means responsive'to the speed of oneic'f saidl motors varying relative to the speed of another motor for further adjusting at least one of said valves to thereby correct said variation in speed.

2. The combination, with two reciprocating hydraulic motors, of two reversible pumps veach hydraulically connected to one of said motors and having hydraulic means for varying its displacement and a valve for controlling said hydraulic means to thereby control the pump, means for supplying liquid through said valves to said hydraulic means, means for shifting said valves in one direction or the other simultaneously to cause said pumps to deliver liquid to one end or the other of said motors and thereby cause said motors to operatesimultaneously in one direction or the other, and means responsive to the speed of one of said motors varying relative to lthe speed of another motor for further adjusting said valves to decrease the speed oi said one moj tor and increase the speed of said other motorv until said variation in speed is corrected.

other simultaneously to` cause said pumps to deliver liquid to one port or the other of said motors and thereby cause said motors to operate simultaneously in one direction-or the other and a follow-up mechanism for moving each valve toward its neutral position i'n response to movement of the displacement varying member of the pump controlled by that valve, and means responsive to the speed of one of said motors varying relative to the speed of another motor for further adjusting at least one oi said valves to thereby correct said variation in speed.

4. The combination, with two hydraulic motors, of two reversible pumps each hydraulically connected to one of said motors and having a member for varying its displacement and hydraulic means for shifting said member, means for supplying liquid to the hydraulic means of each pump including a valve for controlling that pump, said valves being normally in neutral positions and shiftable therefrom to effect operation of said hydraulic means, means for adjusting said valves including means for shifting said valves in one direction or the other simultaneously to cause said pumps to deliver liquid to one port or the i other of said motors and thereby cause said motors to operate simultaneously in one direction or the other and a follow-up mechanism for moving each valve toward its neutral position in response to movement of the displacement varying member of the pump controlled by that valve, and means responsive to the speed of-gne of said motors varying relative to the speed fanother motor for further adjusting said valves to decrease the speed of said one motor and increase the speed oi said other motor until said variation in speed is corrected.

5. 'I'he combination, with a first and a second hydraulic motor, of a rst and a second pump for energizing said first and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for shifting said element, means for supplying liquid to said hydraulic means including a flrst valve for controlling said first pump and a second valve for controlling said second pump, means for adjusting said valves to thereby control the operation of said motors, a three-legged diilerential having a first and a second leg thereof driven in response to movements created by said iirst and second motors respectively whereby the third leg thereof rotates in response to the speed of one motor varying from the speed of the other motor, and means responsive to rotation oi said third leg for further adjusting atleast one of said valves to thereby correct said variation in speed.

6. In a machine having a stationary member, a

platen normally arranged parallel to said member and power means arranged at opposite sides of the center of said platen for reciprocating said platen toward and from said member, the combination of means for pivotally connectingsaid platen to each of said power means, and control means responsive to uneven travel of said platen for adjusting said power means to restore even travel of said platen and including means for adjusting said control means to cause said power means to adjust said platen at an angle to said member. y Y

7. In a machine, the combination of two reciprocating hydraulic motors spaced from each other, a platen normally arranged at right angles to the axes of said motors and pivotally connected to 4 said motors to be reciprocated thereby, two reversible pumps each hydraulically connected to one 0i said motors and having hydraulic means for varying its displacement and a valve for' controlling said hydraulic means to thereby control the pump, means for supplying liquid through said valves to said hydraulic means, means for causing one of said motors to move one end of said platen relative to the other end thereof to change the angle between said platen and the axes of said motors, means for shifting said valves in one direction or the other simultaneously to cause said pumps to deliver liquid to one end or the `other of said motors and thereby cause said motors to operate simultaneously in one direction or the other, and means responsive to the speed of one of said motors varying relative to the speed of the other motor for further adjusting at least one oi said valves to thereby correct said variation in speed.

8. In a machine, the combination of two reciprocating hydraulic motors spaced from eachv other, a platen normally arranged at` right angles to the axes of said motors and pivotally connected to said motors to be reciprocated thereby, two reversible pumps each hydraulically conlnected to one of said motors and having hydraulic means for varying its displacement and a valve for controlling said hydraulic means to thereby control the pump, means for supplying liquid through said valves to said hydraulic means, means for causing one of said motors to move one end of said platen relative to the other end thereof to change the angle between said platen and the axes of said motors, means for shifting said valves in one direction or the other simultaneously to cause said pumps to deliver liquid to one end or the other of said motors and thereby cause said motors to operate simultaneously in one direction or the other, and means responsive to the speed of one of said motors varying relative to the speed of the other motor for -further adjusting said valve to decrease the speed of said one motor and increase the speed of said other motor until said variation in speed is corrected.

9. -In a machine,'the combination of ytwo re.

ciprocating hydraulic motors spaced from each other, a platen normally arranged at right angles to the axes of said motors and pivotally connected to said motors to be reciprocated thereby, two reversible pumps each hydraulically connected to one oi.' said motors and having a member for varying its displacement and hydraulic means for shifting said member, means for supplying liquid to the hydraulic means of each pump including a valve for controlling that pump, means for causing one of said motors to move one end of said platen relative to the other end thereof to change the angle between said platen and the axes of said'motors, said valves being normally in neutral positions and shiftable therefor shifting said valves in one direction or theV other simultaneously to cause said pumps to deliver liquid to one end or the other of said motors and thereby cause said motors to operate simultaneously in one direction or the other and a follow-up mechanism for movingl each valve toward its neutral position in response to movement of the displacement varying member of the pump controlled by that valve, and means responsive to the speed of one of said motors varying relative to the speed of the other motor for further adjusting at least one of said valves to thereby correct said variation in speed. i

10. A machine, comprising a reciprocable member, two spaced apart guides for guiding said member, separate means for connecting one end of said member to one of said guides and the'other end of said member to the other of said guides and adapted to permit one end of said member to be advanced a substantial distance ahead of the other end thereof, a first hydraulic motor for reciprocating one end of said member, a sec'ond hydraulic motor for reciprocating the other end of said member, a first and a second pump for energizing said first and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for shifting said element, means for supplying liquid to said hydraulic means including a first valve for controlling said first pump and a second valve for controlling said second pump, means for adjusting said valves to thereby control the operation of said motors, a three-legged differential having one of its legs driven by said first motor and a second leg driven by said second motor whereby its third leg rotates in response to the ends of said member moving through different distances, means responsive to rotation of said third leg for further adjusting at least one of said valves to thereby maintain said motors in synchronism, and means for causing One of said motors to operate independently of the other and move one end of said member relative to the other end thereof to thereby adjust the angular position of said member relative to said guides.

11. A machine, comprising a frame, a member guided by said frame, a first and a second motor connected to said member near opposite ends thereof to reciprocate the same, a first and a second pump for energizing said first and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for shifting said element; means for supplying liquid to said hydraulic means including a first valve for controlling said first pump and a second valve for controlling said second pump, a three-legged diierential having one of its legs driven by said first motor and a second leg driven by said second motor whereby its third leg moves in response to the ends of said member movingthrough different distances, means for adjusting said valves simultaneously,

vand means for further adjusting at least one of said valves in response to movement of the third leg of said differential to thereby correct any variation in the movement of one end of said member relative to the movement of the other end of said member.

12. A machine, comprising a frame, a member guided by said frame, a nrst and asecond motor connected to said member near opposite ends thereof to reciprocate the same, a first and a second pump `for energizing said first and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for shifting said element, means for supplying liquid to said hydraulic means including a first valve for controlling said first pump and a second valve for controlling said second pump, saidvalves normally being in neutral positions and shiftable therefrom to effect operation of'said hydraulic means, a three-legged differential having one of its legs driven by said first motor and a second leg driven by said second motor whereby its third leg moves in response to the ends of said member moving through different distances, means for adjusting said valves including means for shifting said valves simultaneously from their neutral positions and a follow-up mechanism for moving each valve toward its neutral position in response to movement of the displacement varying element of the pump controlled by that valve, and means for further adjusting at least one of said valves in response to movement of the third leg of said differential to thereby correct any variation in the movement of one end of said member relative to the movement of the other end of said member.

13. A machine, comprising a frame, a member guided by said frame, a first and a second motor connected to said member near opposite ends thereof to reciprocate the same, a first and a second pump for energizing said first and second motors respectively, each .of said pumps having an element for varying its displacement and hydraulic means for shifting said element, means for supplying liquid` to said hydraulic means includng a' iirst valve for controlling said first pump and a second valve for controlling said second pump, said valves normally being yin neutral positions and shiftable therefrom to effect operation of said hydraulic means, a three-legged diiierential having one of its legs driven by said first motor and a second leg driven by said second motor wherebyv its third leg moves in response to the ends of said member moving through different distances, an actuator, a first follow-up mechanism for connecting saidv first Valve to said actuator and to the element of said first pump, a second follow-up mechanism for connecting said second valve to said actuator and to the element of said second pump, means for operating said actuator to cause said valves to be simultaneously shifted from their neutral positions, said valves being moved toward their neutral positions by said follow-up mechanisms in response to movement of said displacement varying` elements, and means for connecting said follow-up mechanisms to the third leg of said differential so that said valves are further adjusted in response to movement ofsaid third leg to thereby correct any variation in the movement of one end of said member relative to the movement of the other end of said member.

i4. A machine, comprising a reciprocable member, two spaced apart guides for guiding said member, separate means for connecting one end of said member to one of said guides and the other end of said member to the other of said guides andadapted to permit one end of said member to be advanced a substantial distance motor for reciprocating one end of said member,

a second hydraulic motor for reciprocating the other end of said member, a first and-a second pump for energizing said first and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for shifting said element, means for supplying liquid to said hydraulic means including a first valve for controlling said first pump and a second valve for controlling said second pump, means for adjusting said valves simultaneously to thereby cause said motors to move both ends of said member in unison, means for' causing one of said motors to operate independently of the other and move one end of said member relative to the other end thereof, a three-legged differential having one of its legs driven by said first motor and a second leg driven by said second motor whereby its third leg moves in response to the ends of said member moving through different distances, and means for fur-l ther adjusting at least one of said valves in response to movement of the third leg of said differential to thereby cause said motors to move both ends of said member in synchronism regardless of whether one end of said member is even with or ahead of the other end of said member.

15. A machine, comprising a reciprocable member, two spaced apart guides for guiding said member, a first shoe slidable upon one of said guides, a second shoe slidable upon the other guide, means for pivotally connecting said shoes to said member near opposite ends thereof, va first and a second hydraulic motor for reciprocating said first and second shoes respectively upon said guides to thereby reciprocate said member, a first and a second pump for energizing said rst and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for shifting said element, means for supplying liquid to said hydraulic means including a first valve for controlling said rst pump and a second valve for controlling said second pump, means for adjusting said valves simultaneously to thereby cause said motors to move both ends of' said member in unison, means for causing one of said motors to operate independently of the other and move one of said shoes relative to the other to thereby cause said member either to be perpendicular to said guides or to be inclined thereto, a three-legged dierential having one of its legs driven by said first motor and a second leg Idriven by said second motor whereby its third leg moves in response to the ends of saidmember moving through different distances, and means for further adjusting at least one of said valves in response to movement of the third leg of said differential to thereby cause said motors to move both ends of said member in synchronism regardless of whether one end of said member is even with or ahead of the other end of said member.

16. A machine, comprising a reciprocable member, two spaced apart guides for guiding said member, a first shoe slidable upon one of said guides, a second shoe slidable upon the other guide, means for pivotally connecting said shoes to said member near opposite ends thereof, a first and a second hydraulic mot-or for reciprocating said first and second shoes respectively upon said guides to thereby reciprocate said member, a first' and a second pump for energizing said first and second motors respectively, each of said pumps having an element for -varying its displacement and hydraulic means for shifting said element, means for supplying liquid to said hydraulic means including a first valve for controlling said first pump and a second valve for controlling said second pumpl said valves normally being in neutral positions and shlftable therefrom to effect operation o1' said hydraulic means, means for adjusting said valves'including means for shifting said valves simultaneously from their neutral positions and a follow-up mechanism for moving each valve toward its neutral position in response to movement of the displacement varying element of the pump controlled by that valve to thereby cause said motors to move both ends of said member in unison, means for causing one of said motors to operate independently of the other and move one end of said shoes relative to the other to thereby cause said member either to be perpendicular to said guides or to be inclined thereto, a three-legged differential having one of its legs driven by said first motor and a second leg driven by said second motor whereby its third leg moves in response to the ends of said member moving through different distances. and means for further adjusting at least one of said valves in response to movement of the third leg of said differential to thereby cause said motors to move both ends of said member in synchronism regardless of whether one cnd of said member is even with or ahead of the other end of said member.

17. A machine, comprising a reciprocable member, two spaced apart guides for guiding said member, a first shoe slidable upon one of said guides, a second shoe slidable upon the other guide, means for pivotally connecting said shoes to said member near opposite ends thereof, a first and a second hydraulic motor for reciprocating said first and second shoes respectively upon said guides to thereby reciprocate said member, a first and a second pump for energizing said first and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for shifting said element, means for supplying liquid to said hydraulic means including a first valve .for controlling said first pump and a second valve for controlling said second pump, said valves normally being in neutral positions and shiftable therefrom to effect operation of said hydraulic means, an actuator, a first followup mechanism for connecting said first valve to said actuator and to the element of said first pump, a second follow-up mechanism for connecting said second, valve to said actuator and to the element of said second pump, means for operating said actuator to cause said valves to be simultaneously shifted from their neutral positions to thereby cause said motors to move both ends of said member in unison, said valves being moved toward their neutral positions by said follow-up mechanisms in response to movement of said displacement varying elements, and means for connecting at least one of said followup mechanisms to the third leg of said difierential so that at least one of said valves is further adjusted in response to movement of said third leg to thereby cause said motors to move both ends of said member in synchronism regardless of whether one end of said member is even with or ahead of the other end of said member.

18. A machine, comprising a reciprocable member, two spaced apart guides for guiding said member, separate means for connecting one end yof saidr member to one 'of said guides and the plying liquid to said hydraulic means including a iirst valve for controlling said iirst pump and a second valve for controlling saidsecond pump', means for adjusting said valves simultaneously to thereby cause said motors to move both ends of said member in unison, a threelegged differential, tw drives for driving two legs of said diieren al from opposite ends of said member to thereby cause the third leg of said diierential to move in response to the ends of said member moving through different disstances, means for further adjustingat least one of said valves in response to movement of the third leg of said differential to Ithereby correct any variation in the movement of one end of said member relative to thevmovement of the other end of said member, and means for causing one motor to operate independently of the other motor and move one end of said member relative to the other end thereof including means for restraining one leg of said differentialjrom rotating and means for rendering ineffective the drive connected to that leg.

19. A machine, comprising a reciprocable member, two spaced apart guides for` guiding said member, a iirst shoe slidable upon one of said guides, a second shoe slidable upon Vthe other guide, means for pivotally connecting said shoes to said member near opposite ends thereof, a first and a second hydraulic motor for reciproeating said nrst and second shoes 'respectively upon said guides to thereby reciprocate said member, a rst and a second pump for energizing said iirst and second motors respectively, each of said pumps having an element for varying its displacement and hydraulic means for 'shifting said element, means for supplying liquid to said hydraulic means. including a first valve for controlling said iirst pump and a secondv valve for `controlling said second pump, means for adjusting said valves simultaneously to thereby cause said motors to move both ends Aof said member in unison, a three-legged diierentiaLitWo drives for driving two legs of said diierential from opposite ends of said member to thereby cause the third leg of said differential to move in response to the ends of said member moving through different distances, means for further adjusting at least one of said valves in response to movement of the third leg of said differential to thereby correct any variation in the movement of one end of said member relative to the movement of the other end of said member, and means for causing one motor to operate independently of the other motor and move one end of said member relative to the other end thereof including means for restraining-"one leg of said differential from rotating and means for rendering ineffective the drive connected to that leg.

20. The combination with two hydraulic motors and means for supplying motive liquid to said motors to energize the same and including means for`controlling the ow of liquidto each motor, means for adjusting said ilow control means to eiect an initial adjustment of one motor relative to the other motor, means for adjusting said iiow control means to effect operation of said motors, and means responsive to a variation in the relative speeds of said motors for further adjusting said flow control means Ito correct such'variation in speed.

2&1. The combination with two hydraulic motors and means -for supplying motive liquid to said motors to energize the same,- of a control mechanism including means for controlling the ilow of liquid 'to each motor, 4means for operating said tive to each other in response to operation of said operating means.

\ WALTER FERRIS.