GB554665A - Improvements in or relating to co-axial oppositely rotating airscrews - Google Patents

Abstract

554,665. Screw propellers. BRISTOL AEROPLANE CO., Ltd., and PRICE, P. R Jan. 12, 1942, No. 456. [Class 114] In hand-controlled pitch-varying mechanism for oppositely rotating propellers arranged in tandem, pitch-changing movements are transmitted to the normally stationary planet-carrier of a differential gear located between the propellers, so that the pitchchanging motor may be normally at rest. The propellers are driven by co-axial shafts 11, 12, and sunwheels 24, 30, carried by sleeves rotatable on one shaft 11, are secured by their sleeves to the two hubs 13, 16, so as to turn therewith in opposite directions. On opposite sides of the sun-wheels 24, 30 are two pitch-varying sun-wheels 23, 31, the sleeves of which are connected by gears 20, 34 to worm-gearing 15, 18 for adjusting the blades of the two propellers. Planet-wheels 36, 39, which are geared together so as to turn in opposite, directions, connect the sunwheels 23, 30, and a second set of planet-wheels on the same planet-carrier 40 connects the sun-wheels 24, 31. The planet-wheels thus couple the hubdriven sun-wheel of one propeller to the pitchvarying sun-wheel of the other propeller. The planet-carrier, which can turn about the propellershaft 11, but is normally stationary, has integral with it a sun-wheel 42, which receives pitch-changing movements from a gear-wheel 43 mounted on a shaft 44, which passes through the propeller-hub 16 and carries at its rear end a gear 45 meshing with a sun-wheel 46 rotatable about the propeller-shaft 12. The gears 43, 45 normally have a planetary movement around the propeller-shafts, but the sun-wheels 42, 46 are stationary. The sun-wheels 46 is integral with a larger gear 47, which receives pitch-varying movements from a pinion 62. The pinion 62 may be turned either by a reversible motor to give a slow pitch change, or by one of two oppositely rotating clutch-plates geared to the propeller-shaft 12, when a quick adjustment is required, as in reversing. Alternatively, the movement of the planet-carrier may be effected by two hydraulic pumps, the throttling of one of which causes the carrier to rotate in one or the other direction.