GB497673A - Improvements relating to illuminating devices - Google Patents

Abstract

497,673. Retractable aircraft &c. lamps. HARLEY, M. C. June 23, 1937, No. 17501. [Class 75 (iii)] A lamp d, adapted to be swung into and out of a fixed housing c<1> in an aerofoil &c., is carried by a pivoted arm d<1> driven by a rotatable disc g<1> having a crank-pin g engaging a slot d<3> in the arm. As shown, the disc g is adapted to be rotated through 270‹ to move the lamp from one extreme position to the other, in both of which positions the lamp is locked by the pin g engaging the inner end d<4> of the slot. A quadrantal part d<2> of the arm passes through, and substantially closes, a slot c<3> in the housing. The disc g may be operated manually from the cockpit &c. by means of a pulley h and a cable j or through pinion gearing, or it may be driven by an electric motor k, Fig. 4, through reducing gear k<1>, a pinion k2 and a hard fibre spur wheel h<1>, resiliently gripped by spring means l between the disc g<1> and a disc g<2> to form a friction clutch. The lamp-circuit may be closed automatically when the lamp has been moved 30 to 40‹ out of the housing by means of a switch controlled by the operating cable &c. or a mercury switch, which may be attached to the lamp. The rotatable handle for a Bowden or other transmission may be provided with a screwed spindle for advancing and retracting a nut &c. to make and break the circuit. Alternatively, the periphery of the disc g<1> may be recessed at q to allow a spring- pressed contact 0<1> to engage a ring contact o<2>, Fig. 3, a fibre member r<1> engaging the periphery of the disc having a stem r<3>, which is fixed in the contact o<1> and slides in the contact o<2>. Specification 484,685 is referred to in the Provisional Specification.