GB561550A - Improvements in and relating to gearing - Google Patents

Abstract

561,550. Toothed gearing. RICHARDSONS, WESTGARTH, & CO., Ltd., SIGNER, J. U., PARSONS MARINE STEAM TURBINE CO., Ltd., and DOUGLAS, L. M. Aug. 19, 1942, No. 11674. [Class 80 (i)] Relates to gearing of the type in which a primary pinion drives two primary wheels each of which drives a secondary wheel through a secondary pinion. Such gearing is disclosed in Specifications 111,329, 116,531, 117,840, 120,257, 125,203, and 146,641, [all in Class 80 (i)], The invention is directed to means for automatically accommodating inaccuracies of the gear teeth. As applied to a turbine installation having an H.P. and L.P. turbine shaft coupled respectively to two double helical primary pinions, each such pinion a, a<1>, Figs. 1, 2, drives two primary wheels b, band b<1>, b<1> the shafts of which carry secondary pinions c, c, c<1>, c<1> engaging a common secondary wheel d. Each primary wheel is single helical and is driven by one helix only of the double primary pinion a or a<1>. The secondary gears are preferably double helical; but may be straight or single helical. The pinions a, a<1> have axial freedom obtained preferably by connecting them to their driving shafts through couplings permitting axial movement. The gear shafts each have two bearings. The secondary gears c, c<1>, d are disposed axially within the primary gears, and the secondary wheel d is preferably double helical with each secondary pinion axially free. To ensure that the turning forces on the two, secondary gears shall differ greatly,. the helical angle of the primary pinions is made small, e.g. 15 degrees, and that of the secondary gears large, e.g. 45' degrees. In a modification, in order that the turbines may be located nearer the gearcase, the two lower primary wheels are arranged at the end remote from the turbines. In both forms, the centres of the primary pinions a, a<1> and two of the four associated secondary pinions c, c<1> are disposed in the same horizontal plane, thus permitting the cover to have a plane horizontal joint.