Patent GB-388830-A (GB)
Title: Improvements in or relating to aircraft having rotative sustaining means
IPC: B64C27/02
Filed: 1931-09-09
Abstract: 388,830. Aircraft with rotary wing systems; brakes. LA CIERVA, J. DE, Bush House, Aldwych, London. Sept. 9, 1931, No. 25318. [Class 4.] In aircraft of the type having a normally winddriven sustaining rotor and a driving connection between the propelling engine and the rotor for starting or assisting its rotation the rotor hub member comprises a part to which the blades are hinged and an axle which is rotatively mounted by means of external bearings in a fixed apex member of the rotor supporting structure and is extended downwardly through the apex member and carries a driving member such as a crown wheel or an epicyclic planetary cage on its lower end or on an extension thereof. As applied to an aircraft in which an apex member 16 is supported by a structure comprising four struts 21 enclosed in the body as described in Specification 379,792, the drive from a tractor engine 61 is transmitted by a shaft 64 to the rotor hub 11. The drive is taken from the engine crank shaft by bevel gearing contained within a casing 62 also containing a clutch operable from the pilot's seat 67 by a lever 65 biased toward the disengaged position by a spring 66. Universal joints are fitted at either end of shaft 64. Hub 11, Fig. 2, is integral with an axle 10 carried by bearings 14, 15 in apex member 16 and extending downwardly at 10<x> into a casing 22 bolted to member 16. Rotatably mounted on axle part 10<x> is a sleeve 24 integral with a crown wheel 25 which meshes with a pinion 26 driven by shaft 64. Bolted to the lower end of axle' part 10<x> is a flanged sleeve 29 to the flange of which is bolted a brake drum 31 coacting with brake shoes 32 carried by a cover-plate 42 fixed to casing 22. A series of dog clutch teeth 33 are formed on the upper surface of sleeve 29 and are adapted to engage similar teeth 34 formed on a sleeve 35 splined to, and slidable on, sleeve 24. Sleeve 35 may be moved downwardly to engage the dog clutch 33, 34, and thus key crown-wheel 25 to axle 10, by operation of a pivoted lever 36 mounted on a cross shaft 37 and operated from a lever 68, Fig. 1, in the cockpit, through a link 70, and a lever 38. Lever 68 is normally biased to the disengaged position by a spring 71. The teeth 33, 34 are of ratchet form to permit over-running of the rotor. At the end of lever 36 is fitted a plunger 40 working against a spring 41 which permits upward movement of sleeve 35 should over-running occur without disturbing the position of the lever 36. The internal expanding brake comprises two shoes 32 pivoted at 43, Fig. 4, and carrying pins 48 at their free ends engaging in arcuate eccentric slots 47 formed in a pair of plates 46 integral with the upper half of a two-part tubular member rotatably mounted in the brake plate 42 and operated by a lever 50 and pull-and-push member 52 connected to a lever 69, Fig. 1, in the cockpit. Anticlockwise rotation of plates 46 from the position shown causes engagement of the shoes 32 with drum 31. An interlocking mechanism is provided for preventing simultaneous operation of lever 50 and lever 38 and comprises an arm 39 fixed to shaft 37, Fig. 2, and a plate 56 movable with lever 50. A slot 57 in plate 56 is moved into engagement with lever 39 when the brake is operated thus preventing rotation of shaft 37 to engage dog clutch 33, 34, conversely when lever 39 is moved, by rotation of shaft 37, it comes opposite a stop 58 on plate 56 and prevents application of the brake. In another form, Fig. 6, the rotor axle is prolonged by a substantially coaxial downwardly extending shaft 87 and the drive from an engine 83 is taken back by a shaft 86 substantially coaxial with or parallel to the crank shaft, the shafts 86, 87 being connected to one another by epicyclic gears carried in a gear box 88 independently supported in the fuselage. Universal joints are provided at both ends of the shafts 86, 87 and provide for limited axial movement. A dog-clutch 97, 98, Fig. 7, with ratchet teeth is placed in the line between shaft 86 and the engine shaft 96. The teeth are formed to permit over-running of the rotor and a spring 104<x> is inserted in the operating gear to permit the clutch teeth to separate even when the clutch control lever is ratchet-held in the " on " position. The epicyclic gear comprises a sun pinion 115, Fig. 8, driven from shaft 86 by bevel pinions 113, 114, a planet cage 120 in driving engagement with shaft 87, and an annulus 117. The last two components 120, 117 are provided with drums 126, 127 respectively co-operating with brake bands 128, 129. One end of each brake band is anchored to the casing and the other connected by a link to a toggle lever 132 or 133 on a hand-lever shaft 134. The arrangement of the toggles is such that movement of the hand-lever in either direction applies one brake band to the associated drum and moves the other further away therefrom, both bands being out of contact with their respective drums in the neutral position of the hand-lever. When shaft 86 is rotating braking drum 127 causes the drive to be transmitted to shaft 87 at a reduced speed. Reverse movement of the brake lever first disconnects the drive then if the lever is moved past the neutral position and arrests the rotor by braking the planet carrier drum 126. The hand-lever is provided with a manually disengageable pawl associated with a fixed ratchet. Specifications 263,988, [Class 4, Aeronautics], and 387,020 also are referred to.