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).
Modifications to the handstarter for 'Buzzard' engines to resolve an issue with the worm return spring.
| Identifier | ExFiles\Box 178\4\ img034 | |
| Date | 1st April 1932 | |
| To 1. From Ha/Yng. c. to EF. c. to AP. c. to Mr. Jaques. MODIFIED HAND STARTER - SCHEME 1591 - 'BUZZARD' ENGINES. Trouble has been experienced in service with the standard handstarter on Buzzard engines due to the worm return spring vibrating and fouling the worm wheel thereby wearing the tips of the teeth although theoretically there should be .25" clearance in the worst position. The feature of the above scheme is that the worm return spring is only just a clearance fit (.010") over the shaft instead of having .110" clearance as in the standard design. Modifications necessary to obtain this were :- (1) A new worm which allows the spring to spigot inside a shroud formed by the collar instead of on the outside of the collar. (2) Removing a small collar from the worm shaft which located the spring diametrically in the old design. In addition a worm return spring of approximately double the strength of the old one was employed. 'Buzzard' 11-MS-5 was used for the test which consisted of carrying out 5 Starts. 28 Throw outs. 1 Backfires. In all the starts and throw outs there was no sign of pulling on the handle such as would have occurred had the worm been binding due to any reason such as the spring tending to jam inside the shroud due to the expansion of the coils in the compressed position. When the gear was stripped all the parts appeared to be in perfect condition. The scheme tested definitely makes it impossible for the old trouble to occur, and in operation is quite as good as the old scheme. We therefore recommend that it should be standardised on production. Ha/E.K.Young. | ||