Patent GB-973141-A (GB)
Title: Improvements relating to winches and winding gear adapted to be used on stationary or mobile machines for mixing concrete and other materials
Inventor: PULLIN CYRIL GEORGE
IPC: B28C7/08
Filed: 1960-04-13
Abstract: 973,141. Hydraulic transmissions; valves. WINGET Ltd. July 11, 1961 [April 13, 1960 ; June 3, 1960], Nos. 13289/60 and 19770/60. Headings F2C and F2V. [Also in Divisions B8 and G3] The hydraulic motor 13, Fig. 2, driving the winch drum 16 for the drag line scoop of a concrete mixer is remotely controlled from a control unit 19 attached to the scoop and which when actuated operates through a pilot valve 10 to shut off a supply return passage 8 from a relief valve 7 so that the supply line 12 to the motor 13 is pressurized. The relief valve 7, Fig. 3, comprises a spring-loaded balance valve 61 in the through passage 50 and operating (in the actuated position shown) to close a seat 63 in the return passage 8 when the line 12 is required to be pressurized for driving the motor 13. The balance valve 61 has a piston portion 60 with a restricted passage 72 to equalize the pressure on opposite sides. Through passages 53A, 54 connect the chamber above the piston 60 with a port 47 in the pilot valve 10. The valve 61 further has a through passage 70 connecting the low-pressure return line 8 to through passages 69, 74 leading to a second port 48 in the pilot valve 10. With the relief valve in the position shown in Fig. 3 in which operator has depressed the plunger 27 of the remote control unit 19 to move the slide 41 of the pilot valve 40 the passages 53A, 54 are closed to exhaust so that the valve 61 is seated. On release of the plunger 27 by the operator, the slide 41 is moved by its return spring 45 to vent the passage 53A, 54 to exhaust through the passages 74, 70. The valve 62 therefore lifts due to the pressure drop across the piston 60 and allows the main supply fluid to by-pass to the return passage 8, and render the motor 13 inoperative. A relief valve 55 is disposed across the passages 53, 74 for the relief of surge pressures. The Specification refers to the operation of the pilot valve 10 by Bowden cable or a solenoid valve. The valve may also be operated by utilizing the exhaust pressure of the internal combustion engine used for driving the concrete mixer. In this case, part of the exhaust is bled off through a flexible pipe connecting the valve 10 and the control unit 19. Operation of the control unit closes an escape passage to build up pressure in the flexible pipe and operate the valve 10. A second control valve 5 for controlling the discharge hopper of the mixer is provided in the supply line and is arranged so that during operation of the hopper ram 23 through line 22 the supply to the winch is cut-off. The valve 5, Fig. 4, comprises a spindle 78 centred to the non-operative position (shown) by a spring 116, with the inlet port 100 and outlet port 102 to the winch motor in communication. For raising the hopper by actuation of the jack 23 the spindle 78 is lifted by the handle 79 so that the outlet port 102 is closed by a land 84 and the supply fluid passed to the single ram supply line 22 through cross passages 94, 95 and an axial passage 93. For lowering the hopper, the ram returns by gravity, the spindle 78 being lowered so that the line 22 communicates with a return line 25 through the passages 93, 94, 95.