Marine crane lifting control
AssigneeBucyrus-Erie Company
InventorRobert E. Dummer
Life of this patent
Estimating the term…
Abstract
A marine crane includes a high speed winch having a hydraulic heave compensating system that automatically controls the crane winch to compensate for the vertical movement of a load during offloading operations. The heave compensating system includes a reversing valve for overriding manual control and for directing control pressure to stroke the pump of a hydrostatic winch drive into its raise mode of operation, and a compensating valve that regulates the displacement of the pump permitting it to develop and maintain only a predetermined pressure in the high pressure main fluid line. The heave compensating system preferably includes a lift control system for automatically hoisting a heaving load only at or near the crest or trough of a wave.
Claims9
In a hoist control for a marine crane having a bi-rotational variable displacement hydraulic winch motor, a reversible variable displacement hydraulic pump operably connected to the motor through opposite main fluid lines, and a control valve operably connected to the pump through a control circuit including control lines leading to opposite sides of the pump, the combination of:
- selectively operable means to divert control pressure from the control valve and direct it through one of the control lines to cause the pump to deliver high pressure fluid to one of the main fluid lines;
- and
- a compensating valve connected between said one main fluid line and the other control line, said compensating valve being responsive to pressure in said one main fluid line and operable to admit said pressure to said other control line so that the pump develops only a predetermined pressure in said one main fluid line, said predetermined pressure resulting in a predetermined line pull that is sufficient to lift a load in a selected light range, but that will allow relative vertical movement of a load in a selected heavy range while maintaining essentially constant line pressure.
In a hoist control for a marine crane having a bi-rotational variable displacement hydraulic winch motor, a reversible variable displacement hydraulic pump operably connected to the motor through opposite main fluid lines, and a control valve operably connected to the pump through a control circuit including control lines leading to opposite sides of the pump, the combination of:
- selectively operable means to divert control pressure from the control valve and direct it through one of the control lines to cause the pump to deliver high pressure fluid to one of the main fluid lines;
- a compensating valve connected between said one main fluid line and the other control line, said compensating valve being responsive to pressure in said one main fluid line and operable to admit said pressure to said other control line so that the pump develops only a predetermined pressure in said one main fluid line;
- lock-out means to block communication between said one main fluid line and said compensating valve;
- a normally closed lift selection valve in the control circuit and operable, only after control pressure is diverted from said control valve by said selectively operable means, to direct control pressure to stroke the motor to its maximum displacement position and to actuate said lock-out means;
- speed sensing means for sensing the speed of the winch;
- and
- normally closed speed-responsive valve means between said lift selection valve and the motor being responsive to said speed sensing means and operable to pass control pressure from said lift selection valve to the motor only when the speed of the winch is less than a predetermined rate.
Dependencies are inferred from the claim text.