New gearbox design for the Wraith III model, comparing it to the Wraith II.
| Identifier | ExFiles\Box 8\11\ 11-page074 | |
| Date | 16th March 1937 | |
| 628 BY. {R.W. Bailey - Chief Engineer} and Rm. {William Robotham - Chief Engineer} SECRET. E {Mr Elliott - Chief Engineer} /HDY. {William Hardy} 1/HP.16.3.37. c. E. {Mr Elliott - Chief Engineer} Da. {Bernard Day - Chassis Design} HPS. {Horace Percy Smith - Experimental Factory Mgr} Wraith III Gearbox. We send herewith N.Sch.5064 showing constant mesh, third and second speed gears with a smaller helical angle and, excepting the constant mesh, with a finer pitch than on Wraith II. The finer pitch gears have to be wider and because of this the centre and rear end diaphragms have to be moved backwards .100 and .250 respectively. No alteration is necessary to the outside of the casing. We prefer this scheme to the Wraith II 45º helical gears because of the reduced end loads which it gives, but as the cost is increased with the greater number of teeth, it is not proposed that it should be adopted immediately, at all events. This drawing also shows other features which should be incorporated in the box for Wraith III whichever gears are used. They are as follows:- (1) Provision for extracting the constant mesh gear and therefore the inner race of the roller bearing, from the layshaft. (2) Increased diameter of gear bosses in some cases. (3) Increased radius in the neck of the 3rd speed driven gear. (4) Standardised radii on the gears. (5) The front cover spigotted on the ball bearing for the constant mesh pinion. (6) Oil holes provided in the constant mesh pinion to lubricate the spigot bush in addition to what is | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).