| 摘要 |
944,257. Clutch-brake combinations and control; friction clutches. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. Aug. 10, 1961 [Aug. 11, 1960], No. 28915/61. Headings F2C and F2L. In a control for an electromagnetic clutch/ brake in a slipping drive for magnetic tapes, there is overlap of the excitation of the windings 3, 5 of driving clutch and stationary brake pole members 4, 6 during the transition from driving to braking and vice versa. In Fig. 8 the windings 3, 5 are excited through potentiometers 14, 15 having sliders 16, 18 controlled by a lever 17, the pivot pin 17a between the lever 17 and the slider 16 being adjustable in a slot 16a to provide excitation overlap in which the current in one winding rises as that in the other falls. Alternatively control may be through grid controlled valves wherein the overlap is adjustable by grid bias. In Fig. 4, clutch and brake armatures 7a, 7b, rotatable with, but axially slidable with respect to, a driven member 2, are constantly urged into light engagement with the pole members 4, 6 by a spring 9. In Fig. 5 (not shown), a single armature is constantly lightly gripped between the brake pole member and a spring-urged clutch pole member which is rotatable with, but axially slidable with respect to, a driving member. In Fig. 6 (not shown), the brake armature is spring urged towards the brake pole member, and the clutch pole member integral with a belt pulley is spring urged towards an axially fixed clutch armature; and for bi-directional drive a further and oppositely rotated clutch pole member and a co-operating further armature may be added. In Fig. 7, the pole member and armature mating faces are respectively provided with a friction coating 12 on an inset ring 11 and a hard smooth, e.g. chromium, layer 13, the remaining iron surfaces of the mating faces being ground back during the running in process and during normal wear of the coating 12 and the layer 13. |
