Patent GB-809149-A (GB)
Title: Improvements in or relating to hydraulic operation of overhead crane carriages
IPC: B66C21/00
Filed: 1956-11-21
Abstract: 809,149. Overhead travellers; winding apparatus; rope railways. LARSEN, B. L. Nov. 21, 1956 [Nov. 21, 1955], No. 35552/56. Classes 78 (4), 78 (5) and 104 (2). A crane carriage, mounted to run on cables or rails, is hauled in opposite directions by two cables with winches connected to separate driving means comprising positive displacement hydraulic motors which are controlled by valves so that one driving means is hauling while the other acts as a brake and also as a pump, restoring power to the hauling means. As shown, the carriage 10, Fig. 1, is hauled along the cable 16 by cables 5, 11 connected to winches 3, 4. The winch 3 is driven by a fluid motor 27, Fig. 2, and the winch 4 by two fluid motors 25, 26, each of which is less powerful than the motor 27, though together they are more powerful. Each of the motors is of the displacement type, and may also act as a pump. Pressure fluid is supplied by a pump 28 driven by an engine 19, and is controlled by two manually-operated valves 29, 30. When the lever 42 is moved to the left, the motors 26 and 27 rotate in the hauling direction (the fluid moving in the direction of the arrows in Fig. 2) until the hook 14, Fig. 1, makes contact with the carriage 10, after which the weaker motor 26 is entrained in the opposite direction by the cable 11 and acts as a pump supplying part of the fluid to motor 27, the carriage 10 moving to the left as viewed in Fig. 1 and the motor 25 idly pumping fluid in a closed circuit 53, 54. With both levers 42 and 50 moved to the right, the motor 25 receives pressure in the unwinding direction (i.e. against the arrow in Fig. 2) and forces the weaker motor 26 to act as a pump, thereby lowering the hook 14. A lowering of the hook under gravity may be achieved by keeping the lever 42 in its central position and moving the lever 50 only part-way to the right, so that all four entries to the valve 30 are inter-connected. With both levers turned to the left, all three motors act in a winding direction, so that the load is first hauled up to the carriage and then moved to the right as seen in Fig. 1, the motor 27 being thus entrained by the cable 5 and forced to work as a pump. By slightly adjusting the lever 42 so that some fluid escapes through the conduit 33, the pressure supplied to the motors may be varied and the log or other load may be dragged along the ground. In another embodiment (Fig. 3, not shown), the cable or rail 16 is dispensed with, the carriage running on the upper stretch of cable 5. With this arrangement the carriage and hook may both be lowered to the ground by varying, the tension in the cables, using lever 42 in the manner referred to above. The hook may be attached to the cable 11 at a point some distance behind the carriage, so that on lowering the carriage to the ground the hook may be attached to objects laterally displaced from the cable. A modification for lifting heavy loads is shown in Fig. 6, the two carriages 101, 10<SP>11</SP> being spaced apart by a rigid bar 58. A tackle such as 20<SP>11</SP> may be used with the other embodiments described above. The required ratios between the hauling powers of the motors 25, 26, 27 may be achieved by using motors of different volumetric capacities, or by using different diameter winch drums or different transmission ratios.