GB551918A - Improvements in or relating to propellers with extended drives - Google Patents

Abstract

551,918. Torsional-vibration dampers. UNITED AIRCRAFT CORPORATION. May 8, 1941, No 6007. Convention date, May 8, 1940. [Class 108 (iii)] [Also in Groups XXXIII and XXIX An airscrew shaft is supported by a bearing carried at the outer end of a tubular member through which the driving shaft extends, the tubular member being secured at its inner end to a structural member which is independent of the engine. The driving shaft is torsionally flexible and the torsional oscillations are hydraulically damped. Hydraulic means for varying the pitch of the airscrew in accordance with the shaft speed, and for feathering the blades, also are provided. The tubular member 18 is secured to a bulkhead 12, Fig. 2, of a nacelle carried by an aircraft wing and its forward end is secured to a partition 61, Fig. 1. A tubular shaft 16 extends from the engine and is splined at its forward end to a second shaft 30 which in turn is splined at its rear and to a third shaft 32 extending to the propeller hub 34 where it is supported by a bearing 72 carried by an extension 68 fixed to the partition 61 on the opposite side to the member 18. The shaft 32 is splined to a ring 42 carrying a series of perforated vanes 46 which alternate with solid vanes 50 carried by an enclosing casing having a flange 54 splined to the shaft 16 so as to damp relative oscillations between the shafts 16 and 32. The casing is kept supplied with oil through passages 58 in the shaft 32 communicating with a chamber therein supplied through a check valve 122. Where a feathering propeller is used it may be of the kind described in Specifications 514,725 or 505,077, [both in Group XXXIII], swivelling blades being rotated by gears 78 on each blade meshing with a gear 80 adjusted by cam followers 84 on a sliding piston 86. This piston is moved in one direction or the other according to whether pressure fluid from a pump 104 is delivered to ports 116 or 118 leading to the inside or the outside of a tube 88 mounted as shown within the shaft 32. The pump 104 is driven by a hollow shaft 98 geared to the shaft 32 by spur wheels 100, 102. The shaft 98 also drives a speed governor 94 which moves a valve within the shaft to control the distribution of pressure fluid through pipes 110, 112 to the ports 116, 118. When it is desired to feather the blades, a second pump 106 delivering at a higher pressure is started up, and the fluid passing through a pipe 155 moves the valve in the shaft 98 to the left to distribute the pressure to the conduit 112, another valve moving to shut off the pressure from the pump 104 which then discharges to the reservoir formed by the casing 68. The Specification as open to inspection under Sect. 91, contains a reference to U.S.A. Specification 308,994/1939. This subject-matter does not appear in the Specification as accepted.