GB599462A - Improvements in friction clutches and brakes - Google Patents

Abstract

599,462. Friction clutches. CLERK, R. C. Sept. 17, 1945, No. 24005. [Class 80(ii)] [Also in Group XXXIV] In a fluid- or electrically-operated friction clutch, or brake, an auxiliary friction device mounted on one main clutch, or brake, element and co-operating with the other, controls the operating means for the main clutch, or brake, so that the latter can only be engaged when the elements are rotating as substantially equal speeds. An annular U-section electromagnet 10 is fast on the driving shaft 12 and a co-operating armature 13 is splined to the driven shaft 14. An auxiliary annular U-sectioned electromagnet 15 is mounted within the magnet 10 and arranged to have relative rotation which is limited by the fixed stops 16, 17 (not shown) and the pin 18. Insulated contact segments 201, 202, 203, 204 attached to the rear of electromagnet 15 co-operate with supply brushes S1, S2, S3, S4 and the main clutch brushes M1, M2, M3, M4. All the supply brushes are connected through a slip ring 21 to one side of the current source, the other side being connected to earth as is one side of the main electromagnet winding. The auxiliary magnet has two windings 25A, 25B connected to adjacent segments 201, 204, and to earth. In operation, if the speed of the shaft 14 exceeds that' of the shaft 12 when the supply brushes and segments 202, 204 are energised, the auxiliary magnet 15 will be clutched to the armature 13 but restrained by the stop 16, therefore segments 201, 203 will remain dead. If the shaft 12 is accelerated until its speed exceeds that of the shaft 14, the auxiliary magnet will lag and move the segments 201, 204 to connect the brushes M2, M3, M4, M1 with supply brushes S1, S2, S4, S3 respectively and thereby energise the main electromagnet when the shafts are substantially synchronised. This will cause the shafts 12, 14 to be clutched together before the auxiliary electromagnet has moved sufficiently to come against the stop 17 (not shown) and cut off the main clutch current. A second embodiment of the invention shows the electromagnetic clutch described above utilised as a brake for the planet carrier of a change-speed gear, and assisted by the torque-responsive cam action of balls accommodated in conical pockets.