US1866801A - Hydraulic crane - Google Patents

Description

July 12, 1932.i l w FERR@A 1,866,801

HYDRAULI G GR NE ATTORN EY Patented July 12,* 1932 p UNITED STATES PATENT -ol-Flca WALTER FERRIS, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE OILGEAB COMPANY, i

OF MILWAUKEE, WISCONSIN', A CORPORATION WISCONSIN HYDRAULIC CRANE This invention relates to cranes and more particularly to hydraulic drives therefor.

One object of the present invention is the provision of a hydraulic drive for cranes so constructed and arranged as to return to the power source a large portion of the energy ordinarily lost during lowering of the load.

.3D In the drawings Another object is the provision of a hydraulic drive for cranes and the like in which two distinct hoisting speeds are available.

Another object is the provision of safety devices for drives of this character which will operate automatically to check the fall of the load in the event of failure in the power cir-y cuit or inthe hydraulic connection.

Another object 'is the provision in a hydraulic circuit of the type involving a reversible flow pump, of mechanism auto'- matically'operable to prevent movementof the motor when pump displacement is zero. Another object is the provision in a crane of a system of reaving which will permit the mounting of the hoisting motor on the bridge without interfering with the hoisting functions or with the free travel of the carriage along the bridge.

i Other objects and advantages will appear from the following description of an illustrative embodiment of the present invention.

Figure 1 is a plan view of a crane embodying the novel featuresof the present linvention.

Fig. 2 is a view partlyA in section and partly in side elevation of the crane of .Figure 1, taken substantially along the line 2-2 of Flgure 1.

` the usual brid Fig. 3 is a diagram of the hydraulic connections. i v l Fig. 4, 5, and 6 are sectional views of three valves, respectively, shown in Figure 3.

The crane shown in Figures 1 and 2 includes -10 mounted for transverse travel along` t e fixed rails 11 in the usual manner, and supporting a carriage 12 mounted to travel alon the usual rails 13 extending lengthwise o the bridge. The carriage is driven .by any appropriate means such as an electric motor 14 geared tothe drivin wheels of the carriage4 in 'a manner weI known. A pair of sheaves 16 and 17 are rotatably supported upon ya shaft 18 fixed at its opposite ends in spaced brackets 15 fixed to f and depending from the central portion of the carriage. The sheaves 16 and 17 are arranged side by side in vertical parallel planes extending lengthwise of the bridge.

A hoisting cable 19, anchored as at 2() at one end of the bridge, is trained over sheave 16, downwardly beneath a padlock sheave 21, upwardly over the sheave 17 ,and then aroundl horizontal sheavesv 22 and 23 rotatably fixed at the other end of the bridge. Thebther end of the cable is operatively connected with a hydraulic motor to be hereinafter described. Sheave 22 and sheavesl and 17' are preferably so disposed that the lengths of cable be- Y tween the anchorage,20 and sheave 16 and between the sheave 17 and sheave 22 lie substantially in one straight line, so that the loop '19 of the cable between sheaves 16 and 17 and sheave 21 remains substantially the same 'length during travel of the carriage 12 along the bridge. The sheave 21 is equipped with a hook 24 vor other appropriate load engagmg means.

The hoisting cable is actuated and controlled by a hydraulic motor which is herein shown as a power cylinder 25 supported in fixed horizontalv position in appropriate brackets 26 secured to the side of the bridge.- A piston 27'within the cylinder is provided with the usual piston rod 28 which carries at its outer end a yoke 29, supporting a pair of sheaves 30 and 31 freely rotatable on ashaft 32 lixed in the yoke 29. A sheave 33 is mounted in a bracket 34 fixed to the opposite end of the cylinder 25. The 'cable 19 extends from the sheave 23 over sheave 30 on. the 'piston rod, then back over the sheave 33 on the cylinder, over the other sheave 31 on the piston rod,

and finallyto the bridge where itis firmly Y anchored as at 35. As the pisto'n 27 travels toward the left, sheaves 30 and 31 move aeeordingly 'and the loop 19 of that portion of the cable between sheave 33 and SheavesjO- and 31 ,is extended. obviously shorbens the loopl 19 of the cableifand, the, hook 24 -is lifted. 'As the piston 27 travels toward the nancy right loop 19" isA shortened and dloop 19'. lengthened to lower the hook 24.

he piston 27 is actuated by a hydraulic circuit, vwithout an accumulator, which circuit is fed by an appropriate pump 36. The

pump shown is a reversible iow, variable displacement pump 'of the type fullydescribed in my applicatio2n,

December 21, v 19 3, which has matured into 1 Patent No; 1,558,002, issued October 20, 1925.A

It will suiiice here to say tliat this pump is driven at substantially constant speed by any appropriate means such as an electric motor 37 and that pum .displ-'a'cement isvaried from zero to fullelivery in either direction by a control stern` 38. When the stem is in the neutral positionl shown pump displacement. is zero. When the stem is shifted lengthwise into the pump casing liquid is zo forced by the pump throu h pipe and returned to the pump throng pipe 39, the rate of flow being determine by the extent of movement of the control stem from neutral position. By shiftin the stem lengthwise in a direction away rom the casing liquid lowsfrom the pump through pipe 39 and returns to the pump through pipe 40. In

this instance the stem is operated by a llever 9, pivotally supported at its lower end upon l0 an appropriatebracket 8 fixed to the pump casing, and pivotally connected at its u per' endwith a rod-7 under the control o the operator through appropriate linkage not shown. The stem is pivotally connected with 35 the lever 9, as at 6. v

Under some conditions of operation the pump 36 acts as a motor, under the pressure of liquid returning thereto through the pipe 40, and when 'so acting delivers a driving torque to the electric motor37. In order to utilize this torque the electric motor 37 is of the regenerative type, such as a constant speed, alternating current induction motor, or a constant spee'd shunt wound direct current motor, which, when driven at a speed above normal, will act as a generator and feed back into the power circuit.

- In the circuit da am illustrated in Figure- 3 it will be not that the pipe 40 is connected to the right end of cylinder 25 through valve mechanisms, hereinafter described, which remain open during normal operation of' the crane., Pipe 40 is also connected f through a branch ppe 41 with a valve 42 un' der the control o e operator. A pipe 43 connects this valve with the left end of the cylinder. Pipe 39 is also connected with this valve 42. Valve 42 is adjustable to connect either ipe'39 or pipe 41 with the left end of der. Although this valve may assume various'forms, that shown comprises a cylindrical housing 44 enclosing a rotatable piston 45 under the control of the operator through appropriate linkage including a rod. f i 47 an arml46 connected with the piston 45.

Serial No. 682,056, filed` LamieraI The piston is cut away so as to open communication between pipes 39 and 43 when in the full line position shown and to open communication between pipes 43 and 41 when in the dotted line position shown.

Provision is preferably made for automatically blocking the escape o liquid from the right end of cylinderA 25 to thereby automatically lock the piston against movement when pump displacement has been reduced to zero or in the event of failure in the power source. The hook 24 andv load supported thereby is thus held against falling when either of the above conditions arise. For this purpose a valve of appropriate type is interposed between the pipe 40 and the right end of the cylinder 25, and this valve is placed under the control of a pilot valve which r'esponds to adjustment of the pump and to the condition of the power circuit. A valve for this purpose is shown in Figures 1, 2, 3, and 5. This -valve comprises a cylindrical housing 50 having two separate chambers 51 and 52. l

Two spaced similar grooves 53 and -54 are formed in the wall of the chamber 51, groove 54 communicating with pipe 40 and' groove 54 communicating with a pipe 40. A piston comprising two heads 57 and 58, connected by a reduced portion 59 is closely fitted for lengthwise reciprocation in the chamber 51. The arrangement is such that when the piston isiin the upper position shown in Figure 5, piston head 57'is above both grooves 53 and 54 and piston head 58 is below both grooves so that pipe 40 is in-open communication with pipe 40. lThis is the position of the piston during normal operation of the crane. When the piston is in the lower position shown in Figure 3, piston head 57 covers groove 53 and communication is eiectively closed between pipes 40 and 40. The piston is controlled bya piston 60 connected thereto by a stem 61 and closely fitted for reciprocation in the chamber 52. l The opposite ends of chamber 52 are in open communication i with pipes 62 and 63, respectively, controlled by a pilot valve of any appropriate type.

The pilotvalve shown comprises a piston having two heads 64 and 65, connected by a reduced portion 66, and closely fitted or lengthwise reciprocation in the cylindrical bore 67 of ,a casing 68. The space between the piston-heads is maintained flooded with liquid under pressure supplied from a convenient pressure source through pipe 69 connected midway of the length of the bore 67. The oppositeends 'of the bore communicate at all times with a discharge pipe 71, through branch pipes 7 2 and 73. A groove 76 in the wall of the casing controlled by the piston head 64 and a groove 77 iscontrolled bythe piston head 65. Pipe 62 is connected with groove 7 6 and pipe 63V with groove 77.- The arrangement is such that when th'e piston is in the lower position of Figure pipe 63 communicates with pressure pipe 69 and pipe 62 with branch pipe 72 and discharge pipe 71, and when the plston-is in the upper position of Figure 4 pipe 62 communicates with pressure pipe 69 and pipe 63 with branch pipe 73 and discharge pipe 71. The piston is controlled by a stem 78.

The pilot valve in this instance is placed under the joint control of the pump control mechanism and a solenoid which responds to the condition of the electric power circuit for the motor 37. In the mechanism shown this is accomplished by mounting a floating lever 79 upon the stem 78 of the'valve. This lever is pivotally connected intermediate its ends to the stem. Theright end lofthe lever is connected with the armature of a solenoid 80. The solenoid is connected through leads 81 and 82 with the opposite sides of the electric power circuit for the motor 37. During the active condition of the power circuit the solenoid is energized and holds the endV of the floating lever 79 in elevated position against the action of the spring 83. Should the power circuit fail, however, the solenoid is deenergized and the end of the lever falls under the action of the spring. A roller 84 journaled within the left end of the floating lever 7 9 rides upon a rotary cam 85 actuated bythe control rod 7 through a rack and pinion 85. With the rod 7, lever 9, and pump control stem 38 in the neutral position of Figure 3, in which position pump displacement is zero, the cam roller is engaged in the depressed portion 86.of the cam 85 and the left end of the lever 79 is depressed. Upon movement of the control rod .7, in either direction from this position, so as to cause the pump to deliver liquid in one direction or the other, the cam 85 is rotated accordingly and the cam roller 84 rises out of the depressed portion 86, lifting the left end of the iioating lever and the valve stem 78.

The arrangement is such that under normal conditions the right end of the floating lever is maintained in an elevated position by the solenoid 80. With the control rod 7 in the -neutral position shown in Figure 3, pump displacement is zero, the c am 'roller 84 rests within the depressed portlon 86 of the cam,

.the valve stem 78 is lowered, and the pilot valve is in such position as to eiect communication between the pressure pipe 69 and' f pipe 63. Fluid pressure is thus applied above the other,ftl1'e cam 3,85 is actuated and the roller 84rises, out of the depressed portion,

thereof and lifts the left end of the floating lever, to thereby elevate the valve stem 78 and lift the pilot valve into the position of Figure 4. `Communication is thus established between the pressure pipe 69 and pipe 62, the piston 60 moves upwardly, and the piston valve in chamber 51 assumes the upper position of Figure and communication is established between pipes 4() and 40. This condition is maintained until the control rod 7 is returned to neutral position-or until yiailure in the electric power circuit. Should the power circuit fail the solenoid would become deenergized and the right endof the floating lever would fall under the pressure of the spring, so as to lower the pilot valve and thereby adjust the valve 50, so as to block the hydraulic circuit. Provision is also made for automatically shutting o the flow of liquidpfrom the right end of the power cylinder in the event that breakage occurs in the pressure pipe 40, to thereby sustain the hook 24 and load against falling. This is .accomplished in this instance by inserting another valve in the hydraulic circuit between the pressure pipe and the right end of the cylinder and by making this valve respond to an excessive rate of flow from the right end of the cylinder to cut off the flow. A valve for this purpose is shown at 88 in Figures 1, 2, 3, and 6. The valve shown is similar to that shown in Figure 5 in that it comprises a piston having two heads 89 and 90 connected by a reduced portion 91 and reciprocating longitudinally in the cylindrical chamber 92 of the valve casing. The space between the heads 89 and 90 is always in open communication with the right end of the power cylinder 25 through a port 93, beneath the head 89, and through a Venturi tube 94 which communicates at all times with the right end of the cylinder. A similar groove 95, communicating with pipe 40 is controlled by the head 90.'A The piston is normally retained in the lower position shown in Figure 3 by a compression spring 96 disposed in the upper endi of the chamber 92. In this posi-.

tion the head 90 is below the groove 95 and pipe 40 is in communication with the Ven-v turi tube and the right end of the power cylinder. When shifted into the upper position of Figure 6, however, the head 90 cov- 'ers the groove 95 and communication .betweenpipe 40 and the Venturi tube is blocked. The piston 1s raised by upward' movement of a p1sto1897 to which it is connected through a stem The. piston 97 reciprocates in a chamber 99 llt within the valve casing. A pipe 100 connects the upper end of chamber 99 with the restrictedpo'rtion of the Venturi tube and a pipe 101 connects the lower end of chamber 99 with a wide portion of the Venturi tube.

The arrangement is such that during normal operationv of the crane the velocity of liquid ilow through'the Venturi tube, to and from the right end of the cylinder 25, is such that the difference in fluid pressure at the restricted and wide portions of the Venturi tube is insufficient to raisethe iston 97 and valve against the pressure of e spring 96.

- Should the hydraulic circuit fail, however,

due for instance to a bursting ofthe p1 40,

so as to permit the high pressure liquid 1n the right end of the cylinder to escape through the venturi at high velocity, the diii'erence in pressure in the tpipes 100 and 101, due to this' hi h' velocity ow.' through the venturi, is

' s cient to lift the piston 97 against the pressure of thespring 96, s as to lift the valve into the position shown in Figure 6. The head 90 then covers the groove 95 and thus eifectively blocks the further escape of liquid from the cylinder. Itis of course understood that the rate of low from the cylinder during normal lowerin is much less than upon rupture and not su cient to cause actuation of. the piston 97.

A brief crane will now be description of the operation of the given. Assume that the motor 37 is running, that the control rod 7 isin the neutral position shown so that pump displacement is zero, that the valves 42:, 50, p

and 88 ,are in the positions shown in Figure 3, and that the ho'ok 24 has been lowered to receive the load. To obtain a slow hoist the control rod 7 is shifted toward the left so as to shift the cam 85 toward` the left and the pump control stem 38 into the pum casing. The pilot-valve is thus lifted into t e upper position of Figure 4, the valve 50 is raised so asto open communication between pipesv 40 and 40', and the pump delivers liquid through these pipes and through valve 88 and venturi 94 into the right end of the cylinder 25. The piston 27 is thus forced toward the left, expanding the loop 19. of the cable 19. and contracting the loop 19' o f the cable to lift the load. During this movementl of the piston 27 the fluid discharged from the left end of -cylinder isreturned to the 36 through pipe 43, valve 42, and pipe 39.

Forrapid hoisting the valve 42 is adjusted into the dotted line position of Figure 3, so

as toopen ,communication between pipes 41 and 43. The-volume of liquid from the left end of the cylinder isthus-directed to the right end thereof and added to the volume of-liquid delivered by the 'pump to thereby obtain rapid travel ofthe piston 27 toward thel right. I Under this condition .both ends of the cylinder are exposed to the delivery side of the pump, so that the unit fluid pressure on both sides of thev piston 27 is the` same. vIt will be noted however that' thearea of the left face of the piston is reduced bythe area of the piston rod-28, so that the pressure available to move the piston 1,see,ec1

trol rod 7 is shifted toward the right so as to adjust the Apump control stem 38 toward the right, and to cause the cam roller 84 to rise out of the depressed portion 86. The valve is thus caused to again assume the upper osition of Figure 5, to reopen commumcatlon tween pipes 40 and 40', and the pump discharges. into the pipe 39. During lowering, the valve 42 isset into the full line position of Figure 3 so that fluid delivered by the pump the cylinder 25 and the piston 27 is effectively vretained against movement.

To eeet lowering of the hook 24, the con' through pipe 39 passes through pipe 43 into y the left end of the power cylinder. The iston 27 moves toward the right, the loop 19" of the hoistingcable contracts and the loop 19 expands, and the hook 24 lowers. Liquid dischar d from the right end of the cylinder passes t rough the venturi 94, valve 88, pipe 40", valve 50 and pipe 40 back to the pum When lowerin' under load the piston Y is actuated prima y by the weight of the load on the hook 24 and by the consequent tension in the loop 19 of the 'hoistingscabla Underl this condltrion the pump ten to speed up under the pressure of the liquid -foreed'from the cylinder 25 through pipe 40 thereto, and

the pump thus as a hydraulic motor tends to up the electric motor 37 so as to cause e same to act as a generator an return power to the electric circuit.

Thus with a constant speedelectric motor of the' t hereinabove mentioned and a variable laement pump various' holstin speeds in a dition to the twoabove describecf,

n as various lowering speeds, may be obtained by adjusting pump' displacement. During lowering un er loa the liquidl re turnin from the cylinder 25 to the pump 36,

Tthrong pipe 40, lsunder pressure proportional tothe load and, acting on the pump, causes the pump to act as a motor, which reacting on the .e ectric motor 37, tends toin- `crease the speed of the motor, therebycausmg the same to act as a generator and to' feed 'power backv into the electric circuit.'y -No matter what lowering speeds have been selected.- the above combination. recouverts the energy of the falling loadinto wer.

Vianous changesmay be made 1n the eln-v bodlment o f the invention. hereinabove speclcally described without departing or sacrificing any of the advantages of the invention as defined in the appended clalms. I claim:

1. In a hydraulic crane, the combination of Va hoisting cable, a piston and cylinder for operating said cable, said piston having faces of unequal areas, a pump for delivering a driving liquid to said cylinder at a predetermined rate, and means adjustable to direct the liquid from said pump to one end of said cylinder for slow hoisting or to direct the liquid from said pump to both ends of said cylinder for rapid hoisting.

2. In a hydraulic crane or the like, the

combination of a hydraulic motor, a variable displacement pump,- hydraulic connections between said pump and motor through which said motor is operated, a. valve in said connections, means for regulating pump displacement, and means responsive to movement of said regulating means for operating said valve to block the flow of liquid through said connections when pump displacement is zero.

3. In a hydraulic crane or the like, the combination of a hydraulic motor, a variable displacement pump for operating said motor, means for regulating pump displacement, and means automatically operable to block communication between said pump and motor when pump displacement is zero.

4. In a hydraulic crane or the like, the combination of a hydraulic motor, a pump for operating said motor, an electric motor for operating said pump and means responsive to a failure in said electric motor for blocking communication between said pump and hydraulic motor.

5. The combination of a hydraulic motor, a variable displacement pump for driving said motor, means for regulating pump displacement, means for driving said pump, a.

cut-olf valve between said pump and motor, and means operable to close said valve when pump displacement is z'ero or in the event of failure in said pump driving means.

In witness whereof, I hereunto subscribe my name this 9th day of February, 1926.

WALTER FERRIS.

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