US3799505A - Crane aiding mechanism - Google Patents

Abstract

A crane aiding mechanism is for use with a crane having a twopart line. A hoist part of the line is engaged with a regular hoist and an aid part of the line is engaged with an aid winch. Coupled to the aid winch is a hydraulic motor-pump connected between a high pressure hydraulic fluid source and a low pressure hydraulic fluid source. The hyraulic motor-pump either drives the winch or is driven by the winch in maintaining the aid part of the line taut. An interconnected, hydraulically actuated brake on the aid winch is operated to stall the aid winch when the regular hoist is operated.

Description

United States Patent 1191 Duncan Mar. 26, 1974 [5 CRANE AIDING MECHANISM 3,381,939 5/1968 Brown 254/172 [75] Inventor. gltilgony Bruce Duncan, Pledmont, Primary Examiner Richard E. Aegerter 1 Assistant Examiner-Hadd Lane [73] Assignee: The Rucker Company, Oakland, Attorney, Agent, or Firm-Lothrop & West Calif.

22 Filed: Nov. 23, 1971 [57] ABSTRACT A crane aiding mechanism is for use with a crane hav- [211 Appl- N04 201,416 ing a two-part line. A hoist part of the line is engaged with a regular hoist and an aid part of the line is en- 52 US. Cl. 254/173 e s with an aid winch- Coupled 10 the aid Winch is [51] Int. Cl 866d 1/48 a hydraulic motor-Pump connected between a g [58] Field of Search 254/150, 186, 172, 185, Pressure hydraulic fluid source and a low pressure y- 254 draulic fluid source. The hyraulic motor-pump either drives the winch or is driven by the winch in maintain- 5 References Cited ing the aid part of the line taut. An interconnected,

UNITED STATES PATENTS hydraulically actuated brake on the aid winch is operated to stall the aid winch when the regular hoist is op- 3,249,336 5/1966 Brown 254/186 stated 3,481,584 12/1969 Conry..... 254/172 3,294,369 12/1966 Butler 254/172 3 Claims, 2 Drawing Figures DATENTEDMARZBIBM 3,799505 sum 1 or 2 lmmo/w 5mm DUNCAN I NVENTOR.

ya /2 M215 ATTOQNEYS 1 CRANE AIDING MECHANISM My invention relates to mechanisms having a variety of uses but particularly involved in the handling of cargo to be transferred between a vessel moving up and down with the motion of the sea and either a stationary pier or another, differently moving vessel.

It is customary to unload cargo from a floating vessel by means of a crane provided with a winch regulating the paying out and taking in of a cable. The cable or line usually runs over a pulley at the head of the crane boom and falls to a hook releasably engaged with the cargo on the floating vessel. A difficulty, especially in unloading, is that the up and down motion component of the vessel being unloaded varies within a short time and thus varies the load on the crane line when it is connected to the load. Various relatively effective devices have been proposed and used for compensating for the rather random vessel motion relative to the crane but most such devices are either so complex mechanically or as so expensive as not to enjoy wide spread use. Part of the reason for this is that sophisticated sensing mechanisms and quick controlling mechanisms, to respond to the precise motion of the vessel being unloaded. are necessary if an exact job is to be done.

It is therefore an object of my invention to provide a crane aidingmechanism to assist in operating a crane hook so that unloading is relatively simple while avoiding the use of complicated or expensive mechanisms.

It is another object of the invention to provide a crane aiding mechanism that can readily be incorporated with standard cranes already available.

A further object of the invention is to provide a crane aiding mechanism that can easily be operated by the operator already available for the regular crane.

A further object of the invention is to provide a crane aiding mechanism that will automatically maintain a predetermined tension of the cargo handling line despite heaving or rising and falling of the vessel being unloaded.

A further object of the invention is to provide a crane aiding mechanism that is hydraulically actuated with a relatively simple and effective hydraulic circuit.

A still further object of the invention is to provide a crane aiding mechanism operated hydraulically in which pumping losses and the like are held to a small value.

A still further object of the invention is in general to provide an improved crane aiding mechanism.

Other objects together with the foregoing are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIG. 1 is a diagrammatic view showing a crane aiding mechanism pursuant to this invention in a typical installation and under a typical condition of use; and

FIG. 2 is a diagram utilizing some hydraulic symbols showing the hydraulic circuitryutilized in connection with the crane aiding mechanism.

The job of unloading cargo from a moving vessel to a pier or between any two relatively moving supports can be accomplished according to the invention. In a typical instance it is assumed that there is a work boat 6 relatively slow moving or stationary and itself floating on a body of water 7, such as the ocean, the surface of which has a random up and down motion. A supply 2 boat 8 positioned and floating alongside the work boat has a substantial vertical component of relative movement with respect to the supply boat.

The work boat is provided with a crane 9 including a turntable 11, for example, and a platform 12 on which the customary crane mechanism and the power supply may be mounted. The crane includes a boom 13 having a pivot connection 14 to the platform 12. The crane boom is maintained in position by a topping line 116 at its outermost end having an anchor 17 to the outboard end of the crane and at its inboard end secured to tackle 18 connected to the framework of the crane and having a line 19 extending to a topping winch 21. In addition, the crane is provided with a regular or standard, power driven hoist 22 on the platform 12 and under the control of the crane operator in the customary way. The driving connections to the hoist 22 and the hoist controls are not illustrated since they are standard.

The hoist 22 has a line 23 running from a drum included in the hoist over a pulley 24 at the outboard end of the boom 13. In the standard or usual case the line 23 extends downwardly to engage a hook 26 having a line 27 dropped to engage a load 28 resting on the deck of the supply boat 8. According to the present arrangement, however, the line part 23, which is the hoist part, does not extend directly to and terminate at the hook 26. Rather, the hoist part 23 passes around a pulley 29 to which the hook 26 is connected. From the pulley 29 the same line, now referred to as an aid part 30, extends around another pulley 31 near the outboard end of the boom 13. The line 30 then is connected to a special, added winch 32 preferably situated on the platform 12 in the vicinity of the hoist 22 and available for simultaneous supervision by the same operator.

As particularly shown in FIG. 2, the winch 32 is engaged by the aid part 30 of the line, the line wrapping around the winch drum in the standard fashion so that as the drum revolves the line can be paid out or taken in and so that the drum can follow the line motion.

Connected to the shaft of the winch 32 is a hydraulic displacement, rotary unit that can serve as a motor or as a pump. For convenience, the unit 33 is usually referred to as a motor. The hydraulic: motor 33 is operable in either direction. The winch 3 2 and the motor 33 are coupled together and either one may be the driver. That is, when the motor 33 is hydraulically driven it drives the winch 32 in a direction to take in the aid part 30. On the other hand, if the aid part is effective to drive the winch 32, the hydraulic device 33 becomes a hydraulic pump. That is, the motor 33 can either drive the winch 32 or be overhauled by the winch 32.

In order that the motor 33 can be appropriately operated and the hydraulic mechanisms can be properly employed, I afford at any convenient place a prime mover 34 which can be a diesel engine, or an electric motor. In this instance the motor 34 is electric. The motor circuitry is standard and is arranged so that the electric motor 34 is continually energized during the working of the crane.

The electric motor 34 has a drive connection 36 to a low pressure hydraulic pump 37, the inlet to which is connected by a pipe 38 to a manual shutoff valve 39 and thence to a filter or screen 41 extending from a reservoir 42 or sump. Since the drawing in FIG. 2 is diagrammatic, it is understood that the reservoir or sump 42 is effective not only as a source of hydraulic liquid to be pumped but likewise is a receptacle to receive the drainage from all of the hydraulic'devices connected to it. This is indicated in the case of the pump 37 by a leakage return line 43 which restores leaked fluid to the reservoir 42.

' The pressure side of the low pressure pump 37 is connected by a conduit 44 through a high pressure filter or screen 46 and through a one way or check valve 47 to a pipe 48 going to the low pressure side of the hydraulic motor 33. When the pump 37 operates the motor 33 can be operated at low pressure.

Since the load on the low pressure hydraulic system varies from time to time and since it is preferred not to providea pump 37 of a size to take care of the maximum possible load, there is connected to the low pressure pipe 48 a low pressure accumulator 49. This floats on the pipe 48, is charged when the load is less than the maximum pump load and supplies the pipe 48 with fluid in excess of the maximum low pressure pump load.

In a'similar, parallel fashion the electric motor 34 through a shaft 51 drives a high pressure hydraulic pump 52', the inlet of which is connected by a duct 53 through a manual shutoff valve 54 and through a filter or screen 56 to the reservoir or liquid source 42. A drain pipe 57 takes any leakage or back drain from the high pressure pump 52 to the reservoir 42.

The high pressure outlet from the high pressure pump 52 is connected by a conduit 58 through a high pressure filter or screen 59 and a check or one way valve 61 to a high pressure pipe 62 extending to a high pressure accumulator 63. This has a function similarto that of the low pressure accumulator 49. The pipe 62 extends through an orifice 64 or flow limiting device effective in both directions of fluid flow and likewise extends to the high pressure side of the motor 33.

It is desired to utilize the output of the low pressure pump 37 for generally charging the hydraulic system and for maintaining it in operating condition. There is afforded a shunt or bypass 66 around the motor 33 with a one way or check valve 67 therein permitting flow from the low pressure pipe 48 into the high pressure pipe 62 to charge the other part of the circuitry but precluding backflow through the bypass 66 from the high pressure side of the circuitry to the low pressure side thereof.

It is preferred to maintain an upper limit on the pressure at which the low pressure pump 37 operates. The pipe 48 has a branch 68 extending to a relief valve 69 which has an adjustable spring 71 to establish or set a blowoff pressure. When the low pressure pipe 48 has a pressure in it in excess of the pressure at which the valve 69 is set, then that excess pressure is transmitted through a connector 72 to the valve 69. The valve 69 is thus opened to vent the excess liquid into a discharge pipe 73 extending through a heat exchanger 74 and a discharge pipe 76 to the reservoir 42. The heat exchanger 74 in some installations may not be necessary but, as will appear hereinafter, sometimes the hydraulic fluid being returned to the reservoir 42 is in sufficient quantity and has had sufficient work done on it so that its temperature is unduly high. Before it is restored to the reservoir 42 its temperature is reduced by the heat exchanger to a fair working value. Should the heat exchanger 74 at any time become-overloaded due to clogging or other reasons, there is a shunt conduit 77 around it, the conduit containing a pressure relief valve 78 so that there is always a path of return for excess low pressure hydraulic liquid to the reservoir 42. With this structure the low pressure circuitry is made operable initially to charge and supply the whole system but at a pressure not to exceed a set amount.

In a comparable fashion the high pressure pipe 62 has a branch 81 leading to an adjustable high pressure relief valve 82, the outlet 83 of which is connected to the heat exchanger 74 and relief valve 78 and so to the reservoir 42. The high pressure system can be operated at any pressure not to exceed the set adjustment of the valve 82. When there is an excess pressure in the high pressure side, that pressure is communicated through a conduit 84 to the valve 82 which then opens and relieves the excess fluid to the reservoir 42.

In starting the system from rest the motor 34 is energized and the pumps 37 and 52 proceed to charge the system in general. After the system has become at least partially filled and the pressure begins to rise substantially, the work load due to the operation of the high pressure pump 52 is relatively great. It is desired to avoid this extra load during the starting phase. For that reason I provide a manually operated valve 91 having a hand control 92 for the operators attention and effective to move the valve between two extreme positions in each of which the valve is resiliently held by a spring pressed detent 93. The valve, as illustrated in FIG. 2, is in one extreme position in which flow is blocked from the inlet 94 of the valve to the outlet 96 thereof leading to the reservoir 42.

The inlet 94 of the manual valve 91 is joined to a pressure controlled valve 97, the body of which is connected on one side by a duct 98 to the high pressure line 58. An outlet conduit 96 from the valve 97 joins the pipe76 leading back to the reservoir 42. The valve 97 is an adjustable pressure relief valve subject to pressure upon it transmitted through a duct 101 connected to the high pressure pipe 62. If the pressure in the line 62 becomes excessive that pressure is transmitted through the line 101 to the valve 97 which then opens at the set value and spills the excess through the conduit 99 and the pipe 76 to the reservoir 42.

Before starting the mechanism, the operator shifts the handle 92 and moves the valve 91 so that it is no longer in the blocked position illustrated but is in a throughflow position connecting the duct 98 to the inlet 94 and through the open valve to the outlet 96 and to the reservoir 42. In this fashion there is no load due to pressure buildup by the high pressure pump 52 during starting. After the system has been started and the lines generally are charged to a low pressure then the operator shifts the handle 92 and restores the valve 91 to its blocked position, as shown. Thereupon there is no further flow through the inlet 94 and the valve 97 thereafter acts simply as a high pressure relief or regulator valve.

After starting and after the valve 91 has been shifted to running position, the high pressure pump 52 increases the pressure on the charged high pressure side and builds the pressure in the accumulator 63 and its connected appurtenances up to the maximum pressure as set by the valve 97. Such pressure is transmitted from the high pressure pipe 62 and through a conduit 102 to a manually actuated control valve 103 having a control lever 104. The valve 103 in one position, as shown, blocks flow from the high pressure conduit 102 past the valve but does permit flow from one side of a hydraulic brake cylinder 106 through a duct 107 and through the valve 103 to the reservoir 42. When the duct 107 is so connected to the reservoir 42, there is no pressure within the cylinder 106 on the left-hand end of a piston 108 therein which thus is moved toward that end of the cylinder by a spring 109. In this position, the piston 108 is effective through a piston rod 111 to apply a brake shoe 112 to the brake drum 113 of the winch 32. The force available at the brake is sufficient to hold the aid part 30 and the entire line to the maximum tension force that can be exerted thereon, either by a maximum load 28 or the maximum force that can be impressed upon it by the hoist 22 even though the pulleys 29 and 24 may be two-blocked.

When the lever 104 is manually shifted to shift the valve 103 to its other extreme position as governed by a detent 114, the valve then interrupts communication with the reservoir 42 but establishes communication from the high pressure conduit 102 through the valve to the duct 107. High pressure is thus exerted on the left-hand side of the piston 108 and is sufficient to overcome the force of the spring 109 and to relieve the pressure of the brake shoe 112 on the brake drum 113. The aid part 30 is thus no longer restrained by the brake 113 and is free to move with the drum winch 32.

Particularly pursuant to the invention, the brake control valve 103 is interconnected with the pipe 62 connected to the hydraulic motor 33. That'is, a pressure connector 116 extends to a valve 117 spring-urged toward one position. In this position, the valve 117 blocks flow through the pipe 62 so that high pressure liquid is not effective upon the motor 33. However, when there is pressure in, the connector 116 the valve 117 is shifted against its spring urgency and directly connects the two parts of the pipe 62. High pressure fluid is then effective to rotate the hydraulic motor 33 and drive the winch 32. Conversely, when pressure is relieved from the brake cylinder 106 so that the brake is then spring-applied, the drop of pressure in the connector 116 is effective to permit the valve 117 to be spring-shifted back to its blocking position and high pressure fluid is no longer supplied to the hydraulic motor 33.

t In the operation of this arrangement the operator attends his hoist 22 in the usual fashion, visually observing the heaving or rising and falling of the supply boat 8 and the load 28 thereon. When the load is about to be affixed to the hook 26, the operator has already charged the hydraulic crane aiding mechanism to the high pressure operating value as described. He operates the hoist 22 for attaching the hook 26 to the load with ample slack in the usual way and then brakes the hoist 22. By operating the lever 104 he then releases the brake 112 and thus simultaneously supplies high pressure fluid to the hydraulic motor 33. This hydraulic motor is then propelled in one direction and rotates the winch 32 in a takeup direction until such time as the aid part 30 of the line and the hoist part 23 of the line are under substantially the same tension, which is resisted by the brake on the hoist 22. However, the load impressed on the aid line 30 by the winch 32 is no more than the maximum output of the hydraulic motor 33 and this is a relatively small amount. It is only sufficient to remove all slack from and maintain a low tension in the line parts 30 and 23 due to the rising and falling of the load 28 on the supply boat 8. That is, the tension is maintained so that the line is always taut but there is not nearly enough tension in the line to lift the load 28.

While normally tension is maintained in the line by the driving force pf the hydraulic motor 33 especially as the boat 8 rises, it may be that the line 30 is pulled out during the dropping of the load at such a rate as to overhaul the normal operating speed of the hydraulic motor 33. During overspeed the motor 33 becomes a pump and tends to transfer low pressure hydraulic fluid from the pipe 10 into the high pressure pipe 62. Such operation is easily permitted, subject only to opening of the high pressure regulating valve 82 should the high pressure become excessive but this usually occurs only after the accumulator 63 has been fully charged and if the flow rate is more than the restricting orifice 64 allows. Being bidirectional, the restricting orifice 64 also limits the maximum winch speed in case ofa hoist line failure.

In all cases a reasonable degree of tautness is always maintained in the aid line 30 despite rising or falling of the boat 8. The operator observes the motion of the load 28 on the supply boat 8 with respect to its rising and falling relative to the work boat 6. He can do this directly but to assist his observation it is convenient to provide an indicator 121 connected by a flexible shaft 122 to the shaft interconnecting the motor 33 and the drum hoist 32. The motion of the drum hoist 32 in both directions is reflected by the indicator 121. The operator with only reasonable skill in observing the indicator 121 can judge with sufficient accuracy when the supply boat 8 is near the bottom of a trough or is near the top of a crest.

At either of those substantially null points he operates the hoist 22 to start taking in the hoist line 23. He simultaneously operates the lever .104. When he operates the lever 104 that shifts the valve 103, drops the pressure in the duct 107 to the brake actuator 106 and permits the spring 109 promptly to apply the brake 112 and lock the drum 32 in position thus holding the aid part of the line 30 stationary against whatever superior force is imposed upon it. At the time the valve 103 is shifted and the cylinder 106 is exhausted above the pis ton 108, the drop in pressure is reflected through the connector 116 to the valve 117. This then shifts from its flow position to its block position and precludes further high pressure hydraulic fluid flow to the pump 33 which no longer is impelled to drive.

The result of the foregoing is that when the operator starts his load lifting function and simultaneously applies the brake 112 he operates immediately with a hoist line 23 which has continuously had a light tension in it and without any slack whatsoever so that the load is taken up properly and without shock.

What is claimed is:

1. In a crane mechanism having a hoist with a controllable power means capable of raising a predetermined load and including a load lifting line having one end thereof connected to said hoist, the improvement comprising:

load lifting means engageable by an intermediate portion of said line;

a line tensioning winch connected to the other end of said line, said winch including a hydraulic drive motor oflimited power, incapable of applying sufficient tension to said line to support said predetermined load;

3. A mechanism as in claim 1 including a hydraulic circuit for said drive motor, having a source of high pressure hydraulic fluid having a high pressure accumulator, a source of low pressure hydraulic fluid having a low pressure accumulator, means for charging both of said accumulators with low pressure fluid, and means for charging only said high pressure accumulator with high pressure fluid.

Claims (3)

1. In a crane mechanism having a hoist with a controllable power means capable of raising a predetermined load and including a load lifting line having one end thereof connected to said hoist, the improvement comprising: load lifting means engageable by an intermediate portion of said line; a line tensioning winch connected to the other end of said line, said winch including a hydraulic drive motor of limited power, incapable of applying sufficient tension to said line to support said predetermined load; a brake adapted to be applied to said winch with sufficient force to hold said other end of said line against any tension applied thereto by said hoist, or to be released therefrom; and operator controlled means for simultaneously de-activating said power means, activating said drive motor and releasing said brake, and vice-versa.

2. A mechanism as in claim 1 including means for simultaneously applying said brake and deactivating said hydraulic motor.

3. A mechanism as in claim 1 including a hydraulic circuit for said drive motor, having a source of high pressure hydraulic fluid having a high pressure accumulator, a source of low pressure hydraulic fluid having a low pressure accumulator, means for charging both of said accumulators with low pressure fluid, and means for charging only said high pressure accumulator with high pressure fluid.

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