Patent GB-533536-A (GB)
Title: Improvements in or relating to power transmissions
IPC: F16H61/40
Filed: 1939-10-12
Abstract: 533,536. Power transmission. VICKERS, Inc. Oct. 12, 1939, No. 27791. Convention date, Oct. 12, 1938. [Class 69 (ii)] [Also in Group XXII] A fluid power transmission device of the kind in which a fluid motor associated with a pump driven from a source of power is combined with a prime mover connected to a load device. As applied to a lathe in which the chuck is driven by an electric motor 10, and the fluid power transmission comprises a pump 16 and a fluid motor 14 operating together as in Specification 380,578, the motor 14 can be used to act as a brake when the motor 10 is active, or as the driving means when the motor is de-energized. The chuck can be driven at normal speed by the motor 14 and can be slowed down to an inching speed and stopped at a predetermined position, or by holding down a switch the inching speed may be continued. The pump 16 delivers through a relief valve 25 to a hydrostatic flow control valve 26 openable to maintain a constant but adjustable rate of flow, and the fluid passes through a pipe 70 to the motor 14, and pipe 30 to a valve 34. A pipe 38 connects :the .motor 14 to a relief valve 40, which can deliver to a pipe 66 or 60 fitted with check valves 68, 64 respectively. The valve 34 has outlets 36, 37 connected respectively to the valve 40 and to a valve 46 which opens a way to the tank 23 when the pressure in a pipe 56 causes a piston 54 to depress the valve against the action of a spring 50. The valve 34 is normally centred by springs but is fitted with operating electromagnets 106, 122, controlled by switches associated with the relay means for operating the switch which controls the supply of power from the mains 85 to the lines 84 of the motor 10. To start the motor, a hand switch 74 is depressed against the action of a spring and energizes the relay of a switch 28 which closes the motor circuit. The action of switch 74 also de-energizes the relays of switches 88, and relay 110 and so de-energizes the magnet 122 and allows the valve 34 to assume its centre position under spring action. The unit 14 then acts as a pump and as a brake to the electric motor 10, the fluid flowing through pipe 38, valve 40, ports 36, 32 of valve 34, pipes 30, 70 back to unit 14, forming a closed circuit fed from pump 16 at pressure of valve 25. To stop the electric drive a push-button 82 is depressed to de-energize relay 78 and thus shut off the driving- current. The magnet 106 is at same time energized and the valve 34 moves to the right, and the fluid circuit is thus altered so as to cause the unit 14 to act as a motor and drive the lathe after decelerating it to an inching speed. This continues until a cam 92 on a shaft driven at the speed of the chuck depresses a switch 94 and de-energizes the relay 98 which permits the valve to move to centre position, and finally through a delay switch 88 and relay 110 the solenoid 122 is energized and moves the valve to the left thus connecting ports 32, 37 and blocking conduit 38 at 36. The exhaust from unit 14 then goes through valve 40, pipe 62, check valve 64 and pipe 60 to tank 22, and back pressure causes immediate stopping of the motor. The liquid from pump 16 can then pass through the valve 34 and the valve 46 opens to allow it to pass back to exhaust. By maintaining the switch 118 closed the drive by the pump 16 and motor 14 can be continued.