US604364A - -brown - Google Patents

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US604364A
US604364A US604364DA US604364A US 604364 A US604364 A US 604364A US 604364D A US604364D A US 604364DA US 604364 A US604364 A US 604364A
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ram
pilot
valve
lever
hydraulic
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66BELEVATORS; ESCALATORS OR MOVING WALKWAYS
    • B66B9/00Kinds or types of lifts in, or associated with, buildings or other structures
    • B66B9/04Kinds or types of lifts in, or associated with, buildings or other structures actuated pneumatically or hydraulically

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  • This invention relates to improvements in hydraulic lifts, especially such as are designed for raising long structures like platforms for railway-trains and cradles of ships.
  • hydraulic power is applied to lifting structures of the great length of railway-platforms and the like, it is'of course necessary to use a plurality of hydraulic lifting-rams. Therefore in the varying conditions of use it will happen that some rams will be doing more and'some less than their proper share of the work.
  • the invention consistsin combining with the plurality of hydraulic rams and their main operating-valves means controlled by the operator and connected with each of the main operating-valves by a tension connection in such manner that the movementof the valves is controlled so as to force all the main lifting-rams to move at the same rate of speed.
  • Figure 1 is a side'elevation ofone arrangement of my invention, wherein the movement of the main h ydraulic valves is controlled by a pilotbeam operated by a pilot ram.
  • Fig. 2 is an end elevation of the same.
  • Fig. 3 is an en- Serial No. 640.791. (No model.)
  • FIG. 4 is an explanatory diagram, on 'an intermediate scale
  • Fig. 5 is an enlarged section: of one of the main valves.
  • Fig. 6 is a section onthe same scale ofthe valve of the pilot-ramflheexhaust being partially opened for raising the platform.
  • Fig. 7 is a section on the same scale of the auxiliary valve for establishing communication directly between the pilotram and the exhaust-main in certain cases.
  • Fig. 8 is a broken side elevation of aform of the invention wherein some other motor than i Q the pilot-ram is employed to shift the pilot-.
  • Fig.9 is an elevation of the left endof Fig. 8
  • jFig. 10 is an enlarged detail of the motor.
  • Fig. 11 is a side elevation of apilotbeam and a double-acting hydraulic ram for shifting the same.
  • valves 6 may be of any suitable construction (the preferred form be ing hereinafter described) and are connected with the usual pressure main 10 and ex haust-main 11, 12 being a check-valve open ing inward. Each valve is operated by bent lever 14, connected with thevalve-stem Q and pivoted, at 15 on any suitable framing.
  • each of said chains 20 is connected to its proper section of platform and at the other end to a device for exerting a variable tension on said chains, so as to control said valves 6 accord ing to the load on the rams, and any device which exerts. such tension is within the scope of my invention.
  • a device for exerting a variable tension on said chains so as to control said valves 6 accord ing to the load on the rams, and any device which exerts. such tension is within the scope of my invention.
  • said device is represented as a beam 22, termed the fpilot-beam, which may be formed of an iron or steel I-beam, preferably nearly as long as the platform 1 and supported in any suitable manner, as on rollers 23, carried by the framing. Inplace of said beam 22 any other suitable device might be substitutedas, for example, a chain kept taut by weights or otherwise and connected with each of the valve-chains 20.
  • the pilot-ram which consists of a hydraulic cylinder 25, within which works a piston 26 on the end of a plunger 27 of half the cross-area of the piston and connected in any suitable manner with the beam 22.
  • valves 32 and 35wil1 The preferred construction of valves 32 and 35wil1 be hereinafter described.
  • Valve 32 is connected by pipes 36 and 37 withthe pressure and exhaust mains,respe'ctively, 38 be-' ing acheck-valve on pipe 37, opening toward the exhaust.
  • Valve 35 is connectedwith the exhaust by pipe 39, 40 being a check-valve opening toward valve 35.
  • Valves 32 and 35 are operatively connected, respectively, with handrlevers and 46, as shown in Fig. 4, and 47 48 are rods connected with hand-lever 45,
  • the mainv hydraulic valves are preferably three way spindlevalves,.as shown.
  • the spindle 53 preferably in two parts, as shown,works with water-tight fit through the packings 54 55 56, the-valvevbodybeing chambered at 57 58, as shown, 59
  • the pilot-valve, Fig. 6, is in essential respects the same as the main hydraulic valves, except that its spindle does not require to be diminished in'diameter at a point corresponding to part 63 of the spindles of said main hydraulic valves, because said pilot-valve does not require to have a chamber 57..
  • parts "in Figs. 5 and 6 are represented by the same reference-numerals, and the pilot-valve requires no further description.
  • the special or auxiliary valve, Fig. 7, is also in general similar to the main hydraulic valve, but has only two ports 70 and '71, respectively connecting with pipe 39 from the exhaust-main 11 and bypass pipe'33 to the pilot-ram. Its spindle 72 also requires only one reduction in diameter, 73 corresponding to the part 63 of the spindle of the main hydraulicvalve.
  • the operation is as follows:.'lo raise the platforms, the operator throws lever 45, so as to move spindle 53 of pilot-valve 32 to the left and open the left end of the pilot-ram cylinder to the exhaust; Then the pressure in the right end of said pilot-ram cylinder moves the ram and the pilot-beam 22 to the left.
  • the main rams 2 2 are 'yet motionless;the chains 20 slacken, lowering the weighted levers 14 until the valves '6 open sufficiently to allow the rams 2 2 to start up.
  • the conductor may also, by means of lever 46 and valve 35, open the cylinder of the pilot-ram to the exhaustmain, in which there is sufficient pressure to drive the pilot-ram and so allow the platform to come to the bottom. It the platform is ascending, the pilot ram and beam 22 stop, the exhaust pressure being prevented by the check-valve 38 from moving the pilot-ram in the reverse direction.
  • the conductor may lower the platform by means of lever 46. connection which controls the main valves compels the movement of all rams 2 at practically the same speedz'.
  • pilot-ram is essentially a motor for moving the pilot-beam 22
  • various other motors can be substituted, and in Figs. 8, 9, and 10 I ill strate the application of an electric motor or the purpose.
  • the pilot-beam 22 is furnished with a rack
  • the tensional i 2? in which meshes a gear 75, driven by a motor 76.
  • a brake-lever 79 provided with a head 80, isequipped with an armature 81, which is attracted to the magnets 82, which are connected with the circuit as y when current is flowing through said motor.
  • r y are the circuit-wires and 85 the switch,which may be operated by a lever 4.5 at some convenient position.
  • lever 45 By throwing lever 45 to the left the operator causes acurrent to energize the motor and magnets 82, and therebyfirst draw down lever 79-to free head 80 from rack 22 and'thenmove the pilot-beam 2i tothe left and raise the rams 2 2, as hereinbefore described.
  • the. switch breaks the circuit, lever 7 9 rises, by reason of spring 83, and looks into the rack 22 and the beam and apparatus stop. Should the circuit break accidentally, the lever 7 9 simi- :larly locks into the rack.
  • the lever 79 can be forced down byhand and gear 7 5 be turned by hand to move the beam 22 by a crank placed on its axle.
  • Fig. 11 shows one form of arrangement of a motor connected with the pilot-beam by multiple gearing, in this'the gearing being two to one, so that the pilot-beam travels twice the distance of the plunger.
  • a doubleactiug hydraulic motor, Fig. 11, consisting of the usual cylinder and plunger 86, can also be applied to move the pilot-beam 22. Sheave on plunger 86 will be double, and one chain 91 will extend from a becket 92 on some fixed part, as the head of cylinder 85, around or partly around one sheave 90 and to a becket 03 on the beam 22.
  • Another chain 95 leads in the opposite direction from a becket 96 on some fixed part of the framing around or partly around the other sheave 90 and to a becket 97 on the beam 22.
  • Said cylinder is connected by pipes 30 31 33 with a pilot-valve similar tov valve 32, Figs. 4 and 6, but not shown, and said valve will be controlled by a lever 45, as described, so that the operator can move beam 22 in either direction, as desired.
  • a special valve 35, Fig. 4: may also be provided to operate as described.
  • my invention- 1 The combination with a platform, a hydraulic motor for lifting the same, and a valve for controlling the motor, of a tensional connection operatively connected with said platform and adapted to throw said valve to various degrees of opening, and an auxiliary motor for actuating said connection, substantially as described.

Description

(No Model.) 5 Sheets-Sheet 1.
T. E. BROWN.
HYDRAULIC LIFT.
e w a I 60 n a e w a P M M 4 WW9 0 mww W N 5 5 Sheets-Sheet 2Q "iii ll l 'l Patented May 24) 1898.
I WE/V701? By w ATTORNEY.
(No-Model.) V
r T. E. BROWN.
HYDRAULIG LIFT.
WITNESSES Mummm. v
(No Model.) 5 Sheets-Sheet 3.
T. E. BROWN.
- HYDRAULIC LIFT. No. 604,364. Patented May 24, 1898.
A 1- 6 v 52 W 5- 56 55 54 w/mqss s; I 7% NW M0 @1045. dW wM/mwmm W '7 3M flQATTOFNEY.
(.No Model.) I 5 Sheets-Sheet 4.
T. E. BROWN.
HYDRAULIC LIFT.
No. 604,364. Patented May 24, 1898.
@- x mel WITNESSES: INVENTOH;
(No Model.) 5 Sheets-Sheet 5.
T. E. BROWN. HYDRAULIC LIFT.
No. 604,364. Patented May 24,1898.
W avwentoa fi I va Q 013 351 Gum" wi l ueqoeo im/.5. (Hmwnamm KM KM Z UNITED' ST TES PATENT OFF1(:E.'
THOMAASAE. BROWN, on NEW YORK, N.
' HYDRAULl LIFT.
SPECIFICATION forming part of Letters Iatent No. 604,364, dated May 2f 1898.
Application filed June 14, 1897.
To all whom) it may concern.-
. Be it known that I, THOMAS E. BROWN, a citizen of the United States, and a resident of the city of New York, in the county and State of New York, have invented certain new and useful Improvements in Hydraulic Lifts, of which the following is a specification. This invention relates to improvements in hydraulic lifts, especially such as are designed for raising long structures like platforms for railway-trains and cradles of ships. When hydraulic power is applied to lifting structures of the great length of railway-platforms and the like, it is'of course necessary to use a plurality of hydraulic lifting-rams. Therefore in the varying conditions of use it will happen that some rams will be doing more and'some less than their proper share of the work. In such circumstances, if we suppose all the operating-valves tobe equally open, the rams doing the least work will rise with the greatest rapidity, and' the result of the unequal motion of the rams will be very inj urious strains on the structures which are being raised.
It is the especial purpose of thisinventidn to provide means for controlling the operation of the rams in such a manner as to compel each ram to move at practically the same speed. I
In its essential elements the invention consistsin combining with the plurality of hydraulic rams and their main operating-valves means controlled by the operator and connected with each of the main operating-valves by a tension connection in such manner that the movementof the valves is controlled so as to force all the main lifting-rams to move at the same rate of speed.
In the following specification and'the ac companying drawings 1 describe several modifications in the apparatus for effecting this result, but all of them applying the prin-' ciple and essential elements of construction just above mentioned.
Referring to the drawings which accompany the specification to aid the description, Figure 1 is a side'elevation ofone arrangement of my invention, wherein the movement of the main h ydraulic valves is controlled by a pilotbeam operated by a pilot ram. Fig. 2 is an end elevation of the same. Fig. 3 is an en- Serial No. 640.791. (No model.)
larged detail of the top of one of the liftingrams, showing its preferred rocker-bearing connection with the platform. Fig. 4 is an explanatory diagram, on 'an intermediate scale,
of the device shown in Fig. 1 and illustrating the. manner in which the pilot-beam is operated and how it controls the main valves. Fig. 5 is an enlarged section: of one of the main valves. Fig. 6 is a section onthe same scale ofthe valve of the pilot-ramflheexhaust being partially opened for raising the platform. Fig. 7 is a section on the same scale of the auxiliary valve for establishing communication directly between the pilotram and the exhaust-main in certain cases. Fig. 8 is a broken side elevation of aform of the invention wherein some other motor than i Q the pilot-ram is employed to shift the pilot-.,
beam. In the figure this motor is electric.
Fig.9 is an elevation of the left endof Fig. 8, andjFig. 10 is an enlarged detail of the motor. Fig. 11 is a side elevation of apilotbeam and a double-acting hydraulic ram for shifting the same.
Referring to Figs. 1 to 7, inclusive, 1 is the I per part of said cylinder and with a downward inclination, Fig. 4, there being a sufficient "waterway around the stops 8 on the bottoms of the rains -2. Said valves 6 may be of any suitable construction (the preferred form be ing hereinafter described) and are connected with the usual pressure main 10 and ex haust-main 11, 12 being a check-valve open ing inward. Each valve is operated by bent lever 14, connected with thevalve-stem Q and pivoted, at 15 on any suitable framing. (Not shown'as being no part of this invention.) The free armof said lever 14.- carries a sheave 16 and a sliding weight 18, said arm being weighted sufficiently to throw the valve '6 open-i. 6., to the right of Fig. 4-when not prevented bythe chain 20. At oneend each of said chains 20 is connected to its proper section of platform and at the other end to a device for exerting a variable tension on said chains, so as to control said valves 6 accord ing to the load on the rams, and any device which exerts. such tension is within the scope of my invention. In Figs. 1, 2, and 4 said device is represented as a beam 22, termed the fpilot-beam, which may be formed of an iron or steel I-beam, preferably nearly as long as the platform 1 and supported in any suitable manner, as on rollers 23, carried by the framing. Inplace of said beam 22 any other suitable device might be substitutedas, for example, a chain kept taut by weights or otherwise and connected with each of the valve-chains 20. In the form of the apparatus shown in Figs. 1, 2, and 4 said pilotrbeam 22 is reciprocated by the pilot-ram, which consists of a hydraulic cylinder 25, within which works a piston 26 on the end of a plunger 27 of half the cross-area of the piston and connected in any suitable manner with the beam 22. p
30 is a connection from the front of piston 26 directly to pressure-main 10. 1
31 is a connection from behind piston 26 to V the pilot-valve 32, and 33 a by-pass to a .spe .30
cial or auxiliary valve 35.
The preferred construction of valves 32 and 35wil1 be hereinafter described. Valve 32 is connected by pipes 36 and 37 withthe pressure and exhaust mains,respe'ctively, 38 be-' ing acheck-valve on pipe 37, opening toward the exhaust. Valve 35 is connectedwith the exhaust by pipe 39, 40 being a check-valve opening toward valve 35. Valves 32 and 35 are operatively connected, respectively, with handrlevers and 46, as shown in Fig. 4, and 47 48 are rods connected with hand-lever 45,
- carried adjacent to or through an arm of lever 14', as shown, and provided with stops 49 50, respectively, so that the motion of lever 14 will in certain circumstances throw lever 45 and pilot-valve 32. i
- Referring to Fig. 5, the mainv hydraulic valves are preferably three way spindlevalves,.as shown. The spindle 53, preferably in two parts, as shown,works with water-tight fit through the packings 54 55 56, the-valvevbodybeing chambered at 57 58, as shown, 59
being the pressure-inlet, 60 the connection to the hydraulic cylinder, and 61 the connection to the exhaust. Said spindle 53 is diminished in diameter at 63 on the pressure side and at 64 on the'exha-ust side. At the latter point are provided V-n'otohes 65, as shown, to
' produce agradual opening and closing of the exhaust, and 65 are similar V-notches to produce a gradual opening and closing of the communication from pressure 57 to the outlet 60 ,to effect a gradual opening and closing 'of the supply. The stuffing-box glands 66 67 and the rings 68 63 in chamber 58 are all as well known in the art, and in general said a valve is of a type well known in hydraulics responding hydraulic cylinder 3, and the proper ram 2 rises; but when it moves to the left it opens communication from the corresponding cylinder 3 to the exhaust, and the ram 2 falls because of the weight of the platform. i
The pilot-valve, Fig. 6, is in essential respects the same as the main hydraulic valves, except that its spindle does not require to be diminished in'diameter at a point corresponding to part 63 of the spindles of said main hydraulic valves, because said pilot-valve does not require to have a chamber 57.. parts "in Figs. 5 and 6 are represented by the same reference-numerals, and the pilot-valve requires no further description. The special or auxiliary valve, Fig. 7, is also in general similar to the main hydraulic valve, but has only two ports 70 and '71, respectively connecting with pipe 39 from the exhaust-main 11 and bypass pipe'33 to the pilot-ram. Its spindle 72 also requires only one reduction in diameter, 73 corresponding to the part 63 of the spindle of the main hydraulicvalve.
The operation is as follows:.'lo raise the platforms, the operator throws lever 45, so as to move spindle 53 of pilot-valve 32 to the left and open the left end of the pilot-ram cylinder to the exhaust; Then the pressure in the right end of said pilot-ram cylinder moves the ram and the pilot-beam 22 to the left. As the main rams 2 2 are 'yet motionless;the chains 20 slacken, lowering the weighted levers 14 until the valves '6 open sufficiently to allow the rams 2 2 to start up. As soon as any valve 6 has opened suffieiently to enable its ram to move as fast asthe pilot-beam 22the ram will take up its chain 20 as fast as the said pilot-beampays it out, and therefore its corresponding sheave l6, lever 14, andvalve will now remain stationary. Since a lightlyloaded ram will rise more rapidly, pressures being equal, than a heavily-loaded one, it follows that alightly-loaded .ram will open its valve slightly, while a heavily-loaded ram 'will open its'valve to a greater degree, and this invention will compel all the rams to move at the same speed. When the operator throws lever '45 so as to bring spindle 53 to center, the pilot ram and beam 22 stop, the rams 2 Similar IIC continuing to raisethe platform and tighten the chains 20' until the valves 6 close and all rams come to rest. Should the rams 2 come to the top of their stroke and butt against cylinder-heads, the pilot-ram, being a little longer, can continuemoving, so as to open said valves 6 wide, leaving all rams under pressure, so that'no movement or settlement can take place during loading'or unloading at the upper landing. In lowering the plat form the operation is the reverse, the pilotbeam 22 moving ahead, lifting the sheaves 16 and levers 14, and opening valves 6 to the exhaust until each ram 2 receives an outlet sufficient to enable it to descend as fast as the pilot-beam moves. 1 3
Should a ram leak in risin-g,-i twill lag until its valve 6 opensi its supply-port sufficiently to balance the leak.
7 Should a cylinder 3 leak while its ram 6." is descending, the rain will tend to run ahead and close the outlet-port of the valve until the discharge is diminished by theamount of the leak, and if the leak is sutficient the ram will continue moving the valve and-will open the pressure-main to the leaking ram. Hence a leaking ram can be controlled up to the limit of a leak equal to the full power-supply.
If, when lifting, a pipe clogs or a sufficient leak exists to prevent a ram moving, weight 18 on lever 1t of this ram will descend-as the pilot-beam moves and will continue descending until lever 14 comes in contact with stop 50 of rod 48 and moves this rod, which in turn pulls lever 45 to the central position, and thereby stops the pilot-ram and in consequence the whole machine. Similarly in descending should a ram 2 fail to respond the similar rod 47 would be pulled and valve 32 brought to center and the machine be stopped.
Suppose that the pressure-main 10 bursts. If the platform 1 is descending, the pilot-ram ceases to move for lackof pressure and the apparatus comes to rest. The conductor may also, by means of lever 46 and valve 35, open the cylinder of the pilot-ram to the exhaustmain, in which there is sufficient pressure to drive the pilot-ram and so allow the platform to come to the bottom. It the platform is ascending, the pilot ram and beam 22 stop, the exhaust pressure being prevented by the check-valve 38 from moving the pilot-ram in the reverse direction. The conductor, as before, may lower the platform by means of lever 46. connection which controls the main valves compels the movement of all rams 2 at practically the same speedz'. e., at the same speed proportionally to the speed of the pilotbeam 22-and prevents any ram from moving the part of the platform to which it is applied more rapidly than other parts of the platform are moved, and thus prevents any undue strains on the platform or apparatus. The particular means for operating the tensional connection thus far described may of course be modified without afiecting the essential invention, and I will now describe certain of those modifications.-
Since the pilot-ram is essentially a motor for moving the pilot-beam 22, various other motors can be substituted, and in Figs. 8, 9, and 10 I ill strate the application of an electric motor or the purpose.
The pilot-beam 22 is furnished with a rack Thus, it will be seen, the tensional i 2?, in which meshes a gear 75, driven by a motor 76. A brake-lever 79, provided with a head 80, isequipped with an armature 81, which is attracted to the magnets 82, which are connected with the circuit as y when current is flowing through said motor. :r y are the circuit-wires and 85 the switch,which may be operated by a lever 4.5 at some convenient position. By throwing lever 45 to the left the operator causes acurrent to energize the motor and magnets 82, and therebyfirst draw down lever 79-to free head 80 from rack 22 and'thenmove the pilot-beam 2i tothe left and raise the rams 2 2, as hereinbefore described. When he throws the lever to the central position to stop beam 22, the. switch breaks the circuit, lever 7 9 rises, by reason of spring 83, and looks into the rack 22 and the beam and apparatus stop. Should the circuit break accidentally, the lever 7 9 simi- :larly locks into the rack. To start the beam again in this'case, the lever 79 can be forced down byhand and gear 7 5 be turned by hand to move the beam 22 by a crank placed on its axle.
Fig. 11 shows one form of arrangement of a motor connected with the pilot-beam by multiple gearing, in this'the gearing being two to one, so that the pilot-beam travels twice the distance of the plunger. A doubleactiug hydraulic motor, Fig. 11, consisting of the usual cylinder and plunger 86, can also be applied to move the pilot-beam 22. Sheave on plunger 86 will be double, and one chain 91 will extend from a becket 92 on some fixed part, as the head of cylinder 85, around or partly around one sheave 90 and to a becket 03 on the beam 22. Another chain 95 leads in the opposite direction from a becket 96 on some fixed part of the framing around or partly around the other sheave 90 and to a becket 97 on the beam 22. Said cylinder is connected by pipes 30 31 33 with a pilot-valve similar tov valve 32, Figs. 4 and 6, but not shown, and said valve will be controlled by a lever 45, as described, so that the operator can move beam 22 in either direction, as desired. A special valve 35, Fig. 4:, may also be provided to operate as described.
Now, having described my improvements, I claim as my invention- 1. The combination with a platform, a hydraulic motor for lifting the same, and a valve for controlling the motor, of a tensional connection operatively connected with said platform and adapted to throw said valve to various degrees of opening, and an auxiliary motor for actuating said connection, substantially as described.
2. The'combination with a platform, a hydraulic motor for lifting the same, and avalve for controlling the motor, of a reciprocating tensional connection operatively connected with saidplatform and adapted to actuate said valve, and an auxiliary motor for actuating said tensional connection, substantially as described.
3. The combination of a platform, a. plurality of lifting hydraulic motors and valves therefor, a plurality of tensional connections each operatively connected with said plat- 5 form and adapted to independently actuate each valve, and an auxiliary motor adapted to actuatesaid tensional connection, substantially as described. i
4:. The combination in hydraulic lifting ap- IO paratus,of a platform, aplurality of hydraulic lifting-rams operatively connected therewith, a main operating-valve for each ram, a pilotram and tensional connections operatively connecting the pilot-ram with said platform 1 5 and each of said main operating-valves,-whereby each of said liftingerams is required to move the same distance proportionally to the V movement of the pilot-ram, substantially as described.
paratus, of a platform, a plurality of hydraulic lifting-rams cperati vely connected therewith, a main operating-valve for each ram, a lever for throwing said valves, a pilot-ram and ten- 25 sional devices from said pilot-ram to each of 5. The combination in hydraulic lifting apsaid levers and said platform, whereby each of said lifting-rams is required tomove the same distance proportionally to the" movescribed.
6. The combination in hydraulic lifting apparatus of a plurality of hydraulic liftingrams, a main operating-valve-for each ram, a pilot-ram controlled by the operator, a tensional connection from said pilot-ramto each main operating valve and an auxiliary valve THOMAS BROWN.
Witnesses:
HENRY- L. BRANT,
CHARLES L. DUAnKE in the exhaust connection from said pilot-ram ment of said pilot-ram, substantially as de-
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2761285A (en) * 1953-09-03 1956-09-04 Julian B Beecroft Control system for power-operated moving members
US2764869A (en) * 1954-08-19 1956-10-02 Origins Inc Means for synchronizing the travel of two or more traveling work elements
US3393635A (en) * 1966-08-25 1968-07-23 Pacific Press & Shear Corp Independently operable press brakes having tandem coupling means

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2761285A (en) * 1953-09-03 1956-09-04 Julian B Beecroft Control system for power-operated moving members
US2764869A (en) * 1954-08-19 1956-10-02 Origins Inc Means for synchronizing the travel of two or more traveling work elements
US3393635A (en) * 1966-08-25 1968-07-23 Pacific Press & Shear Corp Independently operable press brakes having tandem coupling means

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