GB525731A - Improvements in compressed air operated high potential switches - Google Patents

Abstract

525,731. Actuation of switches. HUNDT & WEBER GES. Feb. 27, 1939, No. 6445. Convention date, Feb. 28, 1938. [Class 38 (v)] [Also in Group XXIX] In a high potential electric switch operated by compressed air, opening of a valve admits fluid pressure to another valve which is opened with a snap-action to admit fluid pressure to the main actuating device. In one construction, compressed air enters through a connection i and passes through a chamber 11 and a passage d to a cylinder a to move a piston b connected by a rod c to the switch mechanism. A valve w may close this path. Compressed air also passes through a passage k and past a key valve r which is opened against spring pressure by the upward movement of a piston p which slides in a cylinder n and together with a piston q is carried on a spindle o which is moved manually, electrically, or mechanically. Compressed air allowed through the valve r presses down a cylinder u, which carries the valves w, against a spring h and a snap action toggle device comprising two levers 10 having slides y located in guides z joined by tension springs y'. The cylinder q blocks a passage s and prevents air from reaching the underside of the piston u which moves down slowly until upon passing the dead centre position it moves suddenly to open the passage d and air enters the cylinder a to force down the piston b and operate the switch, the main valve w remaining open when the key valve r is allowed to close. At the end of its stroke the piston b uncovers ports f which connect the system to atmosphere, the pressure above the piston u is reduced and spring h causes the valve w to close with a snap action, leaving the device in order for the next operation. In a modification a second key valve is provided which operates a slide valve controlling ports in the cylinder a above and below the piston b which may thereby be operated in either direction by compressed air. It is also described that uncovering of the ports f may connect the compressed air in the cylinder a to the underside of the cylinder u to aid the spring h in closing the valve w.