GB845054A - Controlling means for attaining equal speeds of two pistons working against resistances - Google Patents

Abstract

845,054. Automatic speed control systems. SCHLOEMANN A.G. June 3, 1958 [June 13, 1957], No. 17674/58. Class 38 (4). [Also in Group XXIX] In a double-billet extrusion press 1, in which two pistons 2, 3 are actuated by variable delivery pumps 6, 7 having adjusting appliances 50, 54 and driven by a motor 56, the speeds of the pistons are maintained equal by varying the delivery of the pump 7 in response to a signal derived from a differential gear 17, 18, 19 connected to the pistons. Racks 17, 18 are coupled through a pinion 19, journalled in bearings carried by a lever system 20, 23, 25 so as to move a sliding arm 27 of a potentiometer R1 when the piston speeds are unequal. Potentiometer R1 and a potentiometer R2 form a Wheatstone bridge; an out-of-balance signal actuates a relay 35 controlling the direction of rotation of a motor 40 driving through a worm and wheel 43, 44, a rack and pinion 47, 45 on which is mounted a slider of the potentiometer R2 and a pivot 48 of a lever 49. Adjustment of the pivot 48 varies the delivery from the pump 7 so as to restore the equality between the piston speeds. The piston speed is set by mechanical displacement of a coupling arm 51. For zero delivery levers 52, 49 and rack 47 are parallel, so that movement of pivot 48 has no effect. In addition, a pivot 55 may be adjusted by a similar arrangement as that for pivot 48, the pivots being moved in opposite directions to correct for a difference in speeds.