Patent GB-886812-A (GB)
Title: Improvements in or relating to engines having variable pitch propellers
Inventor: HAWORTH LIONEL
IPC: B64C11/30
Filed: 1959-01-13
Abstract: 886,812. Controlling variable pitch propellers. ROLLS-ROYCE Ltd. March 16, 1960 [Jan. 13, 1959], No. 1307/59. Class 114. A controlling system for a variable-pitch propeller has a hydraulic piston 41, Fig. 3, connected to the propeller blades, and a stop or stops 44, 45 to limit pitch adjustment urged to the " out " or inoperative position by springs 47 and to the " in " or operative position by hydraulic fluid acting on pistons 46 through pipes 50, 51 under the control of a valve 16 which is manually operated through a mechanical linkage from a lever 14 connected to the shut-off cock 17 in the fuel system of the engine. When the aircraft is on the ground with the engines not running the levers 14 are set in position D so that cock 17 is closed, valve 16 is positioned to connect pressure fluid supply pipes 53 and 55 pipes 50 and 51 so that stops 44 and 45 are moved to their " in " position, and pipes 56 are connected via branches 56a and recess 16d in valve 16 so that the auto-coarsening mechanism is inoperative. When starting the engines the lever 14 is moved to-position A so that, as shown in Fig. 3, the cock 17 is open, pipes 50, 51 are connected to drain pipes 52, 54 hence flight stops 44, 45 are " out ", and pipes 56 are connected together so that the auto-coarsening mechanism is inoperative. In the take-off position C the shut-off cock 17 is open, pipes 50 and 51 are connected to supply pipes 53, 55 so that stops 44, 45 are both " in ", and pipes 56 are disconnected from one another so rendering the auto-coarsening mechanism operative. In flight position B the cock 17 is open, pipe 50 is connected to drain 52 so that high flight stop 44 is " out " whereas pipe 51 is connected to pressure supply 55 so that low flight stop 45 is " in ", and pipes 56 are disconnected so that the autocoarsening mechanism is operative. In position E cock 17 is closed, pipes 50, 51 are connected to 'supply pipes 53, 55 so that stops 44, 45 are " in," pipes 56 are disconnected so that the autocoarsening mechanism is operative, and the feathering lever (inoperative in all other positions) is rendered operative. As shown in Fig. 1, a mechanical interlock 18, 25, 26 is provided between the levers 14 and the throttle levers 10. The interlock comprises a frame 18 pivoted on a bar 15 independently of the levers 14, and a link 25 and lever 26 forming a toggle linkage, the interlock lever 26 being rocked by movement of the throttle levers to the take-off position at which lever 26 is freed from the throttle levers. The lever 26 is rotatably supported on a fixed rod 30 and has arms 27 carrying baulking levers 32, one lying in the path of the throttle levers 10 for the port engines and the other in the path of the throttle levers for the starboard engine, so that the pair of throttle levers associated with a baulking lever 32 cannot be moved together in the power-increasing direction but they can be moved one at a time, thus preventing two engines on one wing being accelerated to their full power at the same time during ground running. A gust lock lever 35 pivoted on the rod 30 has a nose 35a adapted to co-operate with a shoulder 36 on the interlock lever 26 to prevent rocking of the latter when lever 35 is held in the position shown by a catch 37. Prior to take-off, lever 35 is rotated anti-clockwise to move nose 35a from abutment with shoulder 36, thus freeing lever 26 for rotation.