GB594464A - Improvements in or relating to transmissions for driving the sustaining-rotor of a helicopter - Google Patents

Abstract

594,464. Toothed gears; friction and ratchet clutches. BORG-WARNER CORPORATION. Aug. 2, 1944, No. 14762. Convention date, July 14, 1943. [Classes 80(i) and 80(ii)] [Also in Group XXXIII] Gearing, for driving the sustaining and control rotor of a helicopter, comprises a housing 10, enclosing a countershaft speed-reducing g e a r having vertical aligned input and output shafts 13, 14, the latter carrying the sustaining rotor; a power take-off bevel 47 driving the controlrotor and other auxiliaries and driven by a bevel 46 either on the output shaft 14 or on one countershafts 22 of the gear; and an automatic hydraulically-actuated multi-disc friction clutch 27, with speedresponsive and manual control, between the input shaft 13 and the driving pinion 17 of the gear, and serving to disconnect the input shaft from the gearing in the case of power failure to permit both rotors to continue rotating for safe descent without driving the engine. In addition a oneway positive clutch, 26 of the screwactuated facially-toothed type, may be arranged between the final driven element 25 of the gear and the output shaft 14, to permit the rotors to overrun automatically in the event of failure in either the engine or gearing, and a brake (not shown) may act on the gear driven-element 25 to prevent backward rotation of the rotor. The reducing-gear comprises stepped wheels 23, on fixed countershafts 22, meshing the input pinion 17 and a final driven ring- gear 25. The friction-clutch 27 is engaged by oilpressure acting on a piston 34 and supplied by a gear-pump 48, on the input-shaft 13, which draws oil through a filter 53 from a sump 52 and supplies it to the hollow interior of the shaft 13 and thence, through a port 69 to the clutch-operating chamber 33. Below a predetermined speed, the clutch - chamber 33 is directly vented through a port 71 so that clutch-engaging pressure cannot build up. Above that speed, a spring-loaded valve 72 is moved outwards centrifugally, to close the vent 71 and allow clutch engagement. For manual operation the clutch-chamber 33 can also be vented by a manual valve 75 communicating with the interior of the shaft 13 through ducts 60, 56. The one-way clutch 26 comprises driving and driven jaw-clutch members 37, 40, the latter of which is mounted on a helical spline 42 on the driven shaft 14. The faces of the clutch teeth are inclined, as shown, to ratchet under spring-pressure 45 until synchronised. Lubrication of the gearing is effected by the clutch-actuating pump 48, which also pressurises an annular space 59 supplying through passages 60, the hollow fixed countershafts 22, which feed the bearings and gear teeth through ports 62, 63. The one-way clutch 26 receives oil which passes through a spring-loaded relief-valve 64 in the shaft 13, into the hollow spigot of the driven shaft 14 and thence through ports 82, 83 to the clutch-teeth and also to a reservoir formed by a cover 85 on the bevel-wheel 46.