GB558310A - Improvements in or relating to airscrews - Google Patents

Abstract

558,310. Screw propellers. SLAUGHTER, J. T. Sept. 18, 1942, No. 13155. Addition to 517,870. [Class 114] The pitch-changing mechanism described in the parent Specification is modified so that the drive between the airscrew shaft and the hub is effected at two points when the blades are at high pitch, i.e. it is effected partly through the high-pitch bevel-wheel and partly through an independent driving-member which acts on the hub through springs. The hub is driven, as heretofore, by a sliding clutch-sleeve 7, Fig. 1, which is splined to the enlarged end 8 of the airscrew shaft 2, and has splines for engaging the bores of two bevel-wheels 9, 10, both of which are in constant mesh with a bevel-pinion 11 on the root of each blade. The sleeve 7 is automatically controlled by a spring 15 acting in opposition to a centrifugal governor 55. In the low-pitch position, driving-dogs 37 on the bevel-wheel 9 co-operate with dogs 38 on the hub. When the sleeve moves into engagement with the high-pitch bevel 10, its splines also engage the hub of a driving-member 46, the arms 47 of which act on the hub through springs 48, Fig. 3. In the low-pitch adjustment, the arms rest against stops 53. In a modification, in which a reversed pitch of the blades can be obtained, the automatic control is dispensed with, and the sliding clutch-sleeve is operated from the cock-pit. The clutch-sleeve is movable past the low-pitch position, so as to disengage the driving-lugs 61, 62, Fig. 7, and allow the blades to be turned through a predetermined angle until the lugs 61 abut against the ends 63 of recesses 64 in the hub.