Systems for operating and controlling hydraulically driven winches, hoists, windlasses and the like

Claim 1

In a crane system for operating and controlling a winding gear driven by a hydraulic motor of the kind including a stationary cylinder having a plurality of radial bores, a piston displaceable in each of the bores and each having an associated driving means, a cam ring having cam faces engaged by the driving means, and means for selectively supplying hydraulic fluid to the bores to displace the pistons radially in a predetermined sequence and by pressure engagement of the driving means with the cam faces to rotate the cam ring, the system including operator controlled pump means for supplying hydraulic fluid to the hydraulic motor, the improvement of free-run means for applying to the pistons of the hydraulic motor a hydraulic pressure differential to displace the pistons radially inwards and withdraw the associated driving means from contact with the cam faces of the cam ring whereby the cam ring can rotate freely, the hydraulic pressure for said free-run means being derived from a source separate from the pump means supplying said motor, a hoist including said free-run means, movable counterweight means for balancing the load on the hoist, hydraulic means, including second pump means, for moving the counterweight means, wherein the hydraulic pressure for the free-run means is supplied by the second pump means.