Electric drive for casement esp. of tilting window or skylight - incorporates shaft-coupling which is slipped by compression of helical springs as soon as motor output shaft becomes jammed

摘要

The electric motor (4) is installed in a housing (3) joined to the inner face of the opening, with a slip coupling comprising two radial helical springs (11,12) in guides (11a,12a) drilled through a bushing (13) which also encompasses an axial ball-bearing (17). Jamming of the motor output shaft (7) causes the coupling to slip as the springs are compressed, so that the motor and its casing (4a) rotate together about the immobilised shaft until a limit switch within the housing is opened. USE/ADVANTAGE - For ventilation or smoke and heat extn., or with Venetian or roller blinds, shock loads imposed by jamming in any position are overcome and either linear or rotary drive may be chosen.