Patent GB-573401-A (GB)
Title: Improvements in or relating to multi-speed governors
IPC: F16H61/02
Filed: 1943-01-06
Abstract: 573,401. Fluid-pressure servomotor-control systems. UNITED AIRCRAFT CORPORATION. Jan. 6, 1943, No. 284. Convention date, Nov. 14, 1941. [Class 135] [Also in Group XXVI] A power plant including a change speed gear between a driving and a driven device and controlled by a speed-responsive governor driven by the driven device, has the governor adjusting means associated with the change speed gear control and operative to change the governor speed setting when the change speed gear control is operated to vary the gear ratio to reduce the speed difference between the driving and driven gear elements to facilitate the gear change and prevent an excessive change in engine speed during shift of the gear. When associated with a variable pitch propeller, the device maintains a substantially constant engine speed for different ratios of the change speed gear. In the form shown in the Figure, the blades of the propeller 12 are adjusted by a single-acting power piston 98 loaded by a compression spring 108 and acting through rods 102, 104 and slip ring 106. The power piston is controlled by a centrifugal governor 62 driven by a propeller shaft 14 through bevel gearing 69, 70 and toothed gearing 72, 74 which gears also drive a motive fluid pump 68 regulated by a relief valve 80. The pump outlet is connected by a passage 78 with a port 82 in a fixed sleeve and a second port 90 in the sleeve is connected with the power cylinder. Connection between the port 90 and the pressure port or a drain port is controlled by a tubular ported valve 86 moved by the governor fly-balls 66. A follow-up valve 156 co-operating with the port 90 is coupled by a lever 150 to a piston 145 loaded by a spring 158 subject to fluid pressure produced by a piston 164 arranged in a cylinder 162, arranged in tandem with the power piston. The propeller shaft is connected to the driving shaft 18 by a two-speed epicyclic gear 20. This gear comprises a fixed toothed annulus having two sets of teeth 24, 26, a pinion 28 on the driving shaft and a pinion 30 on the propeller shaft. The planet pinions have three sets of teeth, the teeth 44 being in permanent gear with the pinion 30 and the teeth 46 in permanent gear with the pinion 28. In the low gear position shown, the teeth 46 mesh with the teeth 26, while in the high gear position the teeth 48 mesh with the teeth 24. The planet pinions are moved to change gear by a double-acting piston 40 controlled by a manually-actuated valve 52. The governor is loaded by a spring 88 bearing against a piston abutment slidably mounted in a cylinder 110 provided with a rack 118 in engagement with a pinion 112 rotatable by a pulley 114, A spring 116 between the closed end of the cylinder and a cap takes part of the spring load and facilitates operation of the pulley. The cylinder 110 is connected by pipes 120, 128 either to an exhaust port 130 or a pressure line 124 by a valve 126 actuated by a spring-loaded piston 132. The cylinder housing the piston 132 is connected by a pipe 138 to the gearchanging cylinder 140.. In the low gear and neutral positions the pipe 138 is connected to drain by a passage 142 in the piston 40. When the piston 40 is moved to change the gear into high gear, pressure is admitted to the pipe 138 which moves the valve 126 to admit pressure to the cylinder 110. This moves the piston spring abutment downwards into contact with a stop 144 so increasing the tension of the loading spring to raise the speed setting of the governor. In a modification, in place of the piston spring abutment and valve 126, the piston 132 moves between stops to vary the position of the fulcrum of the lever 150 to cause an increased speed setting when the gear is moved into high gear. Specification 573,400 is referred to.