Patent GB-441026-A (GB)
Title: Improvements relating to variable pitch propellers
IPC: B64C11/36
Filed: 1934-07-30
Abstract: 441,026. Screw propellers. MEON, H. C., 3606, West 127th Street, Cleveland, Ohio, U.S.A. July 30, 1934, No. 22165. [Class 114] In a variable-pitch screw propeller the mechanism for changing pitch includes two gear members which are relatively movable to selectively connect with the blade controlling member and with another member for determining the direction of change, and means are provided for obtaining relative rotation between these gears when connected to the blade mechanism. The propeller blades 5 are screwed into end caps 6 and rotatably mounted in the hub sockets 2 by ball-bearings 7, 8 and rings 9. The caps 6 have reduced ends 12 which cooperate with bearings 13 pressed into sockets 14 in the inner ends of the hub sockets. Gears 15 are formed on the peripheries of the caps 6 adjacent to flange 20. The gears 15 mesh with worms 22 mounted in transverse bores 23 and bevelled gears 27 are secured to the ends of the worm shaft 22a. The back of the hub is provided with a circular recess 47 into which the main actuating mechanism is fitted and these include a gear 32 which is adapted to be driven in either direction by a spiral gear 53 on a disc 50 which carries on its other face a number of lugs 55. An internal toothed ring 56 is formed with teeth and is provided at the side with lugs 59 and 60. An externally toothed ring 61 with teeth 62 has similar lugs 64 and 65 on its faces. This gear has fewer teeth than the gear 56 and is assembled to be always in mesh therewith. The closure ring 66 has an annular flange 68 with its periphery threaded at 69. This disc also has spaced lugs 70. Two clutch rings 71 are provided on either side of the meshing gears and have notches 72 cut therein of the same size and shape as the lugs 55, 70. For moving the parts a gear control member 74 is used which has a concentric portion 75, a flange 76 and a shoulder 78. The member is bored concentrically for about half its depth and threaded at 79, while the remainder is bored eccentrically at 80. The assemblage is completed by a ring 81 flanged at 82 and threaded at 83 into the bore 79. This ring has a concentric bore which lines up with the bore 80 when assembled, and the shoulders on the two parts 74, 81 hold the gear 61. The external control unit comprises an annular casing 85 bolted to the engine and having at its periphery a groove with helical slots therein through which pins 96 project and engage two rings 91. These rings are provided with bearing services 93, 94 which engage the flange 76 on the movable member 74. Pins 96 are carried by a ring 89 sitting in the groove 88 and the ring is movable by linkages from the cockpit on the aeroplane. When the ring 89 is rotated in one direction, the control member 74 is moved and the lugs 64 on the ring 61 are brought into engagement with lugs 55 on the spiral gear 50. At the same time the springs 112 move the clutch ring 71 against the lugs 60 on the gear 56, so that the lugs 73 also engage the lugs 60 on the gear 56. Thus the gear 56 is clutched to the hub and will be held from rotating in respect thereto. The control member 74 is held stationary by the engagement of the ring 91 with the brake linings 93, 94 and as the hub rotates the internal gear 56 rotates with it. This causes the gear 61 to rotate on the control member 74, and gives to it a slower rotation with respect to the hub. As the gear 61 is clutched to the spiral gear 50 the latter will rotate and turn the blades through the gear 32. Similarly when the ring 89 is rotated in the opposite direction a reverse engagement of the parts takes place. For preventing the blades from being moved too far a stop mechanism is introduced which consists of a clutch member 35 having a cylindrical body portion 115 clutch face 37 annular flange 116 and a keyed connection with the shaft 28. An externally threaded ring 118 is slidably keyed at 119 on the body part 115. When the gear 32 is rotated it engages the clutch member 35 and the rings 118 are moved away from the gear 32 and the ring 123 moved toward it. After the predetermined number of revolutions the ring 118 engages the flange 116 and moves the clutch face 37 out of engagement with the face 33 whereby the gear 32 rotates without rotating the shaft 28.