GB614738A - Improvements in and relating to one-way drives and detents with magnetic locking - Google Patents

Abstract

614,738. Ratchet clutches; positive detents. BRITISH THOMSON-HOUSTON CO., Ltd. July 23, 1946, No. 21948. Convention date, July 24, 1945. [Classes 80 (ii) and 80 (iv)] [Also in Group XXXIV] In a one-way clutch or detent having two relatively rotatable members of magnetic material comprising respectively a wheel and a co-acting friction or positive pawl pivotable to engage or disengage the wheel, one of the members is permanently magnetized and a magnetic force between the members is employed to bias the pawl towards engagement. As shown, the pawl 8, Fig. 3, or 5, Fig. 1, is a centrallypivoted permanent magnet having oppositely polarised ends, and the wheel 7 or 3 is radially polarised so as to attract one end of the pawl and repel the other. With the friction pawl 8, which has a one-way jamming cam surface 9 co-acting with the smooth periphery of the wheel 7, such magnetic interaction biasses the pawl clockwise to initiate jamming. The cam surface 9 may be formed on a hardened insert 18 of non-magnetic material. In the case of the positive pawl 5, the magnetic interaction biasses the pawl anti-clockwise to engage a ratchet end thereon, whose tip 6 may be of non-magnetic material, with ratchet teeth on the wheel 3, whose operative surfaces may also be non-magnetic.. The pawls are mounted on discs 4 and both the pawl 5 and wheel 3, or the pawl 8 only, may be inverted to reverse the direction of locking. The magnetisim of the wheel may be residual, following initial polarisation by temporary energization of a coil 15, Fig. 4, in which case, or if the coil is permanently energized, the polarisation may be reversed by changing the battery connections 17 of the coil so as to magnetically bias the pawl to disengage the wheel. In Figs. 5 and 6 (not shown), permanently magnetized friction and positive pawls respectively are pivoted at one end and may then operate solely by inducing magnetism in the wheel.