GB584450A - Electrically operated pitch changing mechanism for screw propellers - Google Patents

Abstract

584,450. Variable - pitch propellers. FORSYTH, A. G., and FAIREY AVIATION CO., Ltd. June 30, 1944, No. 12491. Convention date, Aug. 12, 1943. [Class 114] A control device for an electrically-operated, variable-pitch propeller, controlling two operating electric motors, is mounted centrally at the top of the operating gear housing. Two electric motors 10, 12 drive the worm-wheel 28 which is splined to the shaft 30. This shaft', through gearing 32, 34, arm 36 and sleeve 38 turns the gear ring 40 which operates the pitchchanging gear mounted on the propeller hubs, as described in Specification 580,488. Teeth on the sleeve 38 and teeth 50 on the ring 52 driven by the engine engage wheels 54 and 56 respectively. Relative movement between these wheels, caused by operation of the pitchchanging motors moves the nut 66 along the screw 64, this nut operating limit switches 68, 70, 76 and 78. With the hand control switch 86 in the position shown (Fig. 4), the motors 10, 12 operate to bring the propellers to coarse or fine pitch according to which of the switches 82 or 80 is closed by the engine-driven governor 84, movement in each direction being stopped by the limit switches 76, 70. Power from the motor is supplied by one of the batteries 92, 94. For feathering, the switch 86 is moved to contact 88 and both batteries are placed in series to give a quicker motor movement. Reversing is similarly effected. Switch 110 ensures that reversing current takes place until the engine speed has fallen below a predetermined r.p.m.