GB382498A - Improvements in or relating to electromagnetically operated reciprocating devices such as electric hammers - Google Patents

Abstract

382,498. Reciprocating machines ; converting electric currents. IGRANIC ELECTRIC CO., Ltd., 147, Queen Victoria Street, London.-(Assignees of Stansbury, C. ; 12th Avenue, Milwaukee, Wisconsin, U.S.A.) Feb. 10, 1932, No. 3967. Convention date, Feb. 20, 1931. [Classes 35 and 38 (ii).] The winding of an electrically operated hammer or other reciprocating member is supplied from a discharge tube with periodically interrupted current, the restarting of current after an interruption being delayed by a transient potential applied to the grid of the tube, a discharge circuit controlling the rate of leakage of said potential. A hammer 1, Fig. 1, operated from D.C. mains L1, L2, has two windings 1b, 1c respectively in series with discharge tubes 2, 3. Unequal characteristics of the tubes and impedances of the coils cause one tube, say tube 2, to commence to discharge before the other, the resultant drop in potential of the plate 2b producing a corresponding transient drop in the potentials of the grid 3c and plate 3b of the tube 3 through condensers 4, 5. The tube 3 is thereby prevented from discharging until its grid and plate have again attained their normal potential, the time of charging up of the grid being controlled by variable resistances 7, 8. When tube 3 commences to discharge it similarly causes tube 2 to stop discharging for a time determined by resistances 7, 8. The coils 1b, 1c are thus alternately supplied with current of separately variable amount. A hammer 10, Fig. 2, has windings 10a, 10b in circuits including tubes 13, 14 and the halves of the centretapped secondary of a transformer 12 connected to an A.C. supply 11. The tubes discharge in alternate half-cycles, the windings being thus alternately energized. The discharge is delayed by the transient negative potential impressed on the grid upon the interruption of the current in the other tube, through condensers 15 or 16, the length of the delay being controlled by variable resistances 17, 18.