GB791594A - Improvements relating to double reduction gearing for marine propulsion - Google Patents

Abstract

791,594. Toothed gearing. FAIRFIELD SHIPBUILDING & ENGINEERING CO., Ltd. Feb. 6, 1956 [Feb. 8, 1955], No. 3668/55. Class 80 (1). [Also in Group XXXIII] In marine propulsion double helical toothed reduction gearing 10, 13, 19, 24, wherein a sliding tooth coupling 22 and a quill shaft 17 interconnect the tubular shafts 14, 20 of the gear 13 and pinion 19, and wherein the gear 13 is located with clearance by thrust bearings 15, 16, means such as a spring-loaded plunger 42 hold the gear 13 clear of the bearing 15 at low shaft speeds. If, under high-speed-ahead conditions of maximum propeller thrust, the main thrust bearing block 27 locating the propeller shaft and gear 24 distorts and the coupling 22 binds, the gear 13 may move with the pinion 19 towards the bearing 15 to accommodate the change in axial position of the gear 24. The device 42 thus avoids wear on the bearing 15 or uneven loading of the helical gear teeth should the coupling 22 bind. The axial clearance in bearings 15, 16 is greater than that in the main thrust bearing 27. The plunger 42 acts through a ball or roller bearing and is mounted in a casing attached to the ship's hull, means (not shown) being provided for adjusting the spring loading. The spring loading may be adjusted to counteract the gravitational thrust on the shaft 14 when the ship is trimmed by the head to the maximum permissible degree. A similar spring device may be applied to the other end of shaft 17 for use during astern propulsion and trimming by the stern, and means be provided for rendering the appropriate device active. In a modification obviating the use of a spring- loaded plunger the straight teeth of the coupling 22 are replaced by helical teeth providing the required axial loading on the wheel 13.