GB518274A - Improvements in or relating to electro-magnetically controlled hydraulic reciprocating mechanism - Google Patents

Abstract

518,274. Sawing. WADKIN, Ltd., GODDARD, J.,H., and SIMS, W. L. Aug. 18; 1938, No. 24351. [Class 145 (i)] [Also in Group XXIX] An electromagnetically-controlled hydraulic reciprocating mechanism of the type comprising a pump 20, Fig. 2, supplying fluid under pressure to pipes 18, 19 leading to opposite ends of a cylinder 15 in which works a ram 16 arranged to operate limit switches to control electromagnetic means operating valves controlling the supply of fluid to the cylinder is so constructed that on operation of the limit switches 34a, 34b one electromagnet is de-energized and movement of a rocking armature permits reversing of one piston valve 26 and the armature operates a switch in the circuit of a second magnet and the energization of this operates the second valve 27 so that the movement of the ram 16 is reversed. The invention is shown as applied to a sawing- machine in which an electrically driven saw 12, Fig. 1, is carried by a slide 13 operated by the ram 16. At the end of the forward stroke of the slide 13 an adjustable stop 41 on the slide operates a limit switch 34a which de-energizes coil 32b and so effects an operation of the valves 26, 27. At the end of the rearward movement of the slide 13, a stop 42 actuates the limit switch 34b but reversal may be delayed by a time switch 37 which, can be set to delay the forward movement so as to give time for the operator to make adjustments. A hand or foot operated main switch 36 is arranged in the circuit of the forwarding control devices, and as shown in Fig. 4 the circuits of the two controlling magnets are in parallel. A choke valve 38, Fig. 2, may control the pressure of the supply fluid, and in the pipe 39 leading back from the pressure side of the pump to the reservoir 21 a loaded relief valve 40 may be arranged: Two valves may be operated by one electromagnet only, and the operation of the stops 41, 42 on the switches 34a, 34b may cause a circuit to be closed instead of opened and an electromagnet to be energized, instead of de-energized.