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).
Non-standard gear failure in an L.H. Phantom II gearbox and spiral angle specifications.
| Identifier | ExFiles\Box 15\5\ Scan315 | |
| Date | 2nd June 1932 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Da.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} N7310. Hs.{Lord Ernest Hives - Chair}4/KT.2.6.32. L.H. P.II. GEARBOX We are afraid we did not make it sufficiently clear in our report Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}2/KT.24.5.32., that the gear which failed was not a standard one. The standard spiral angle on L.H. P.II. boxes is 21°. Early on in production of the L.H. cars, there was considerable difficulty in getting gears passed because of noisy sideshaft gears. The 40° angle gear was put in hand at that time. The troubles subsequently proved to be caused by oil being trapped, and was overcome by our giving a little more clearance. We thought the failure would be of interest as it appeared to show a weak section in this place. Although the L.H. and R.H. P.II cars have a 21° spiral angle, with the synchromesh box it is increased to 32° the same as on the 25 HP. Experience has shown, both on gearboxes and on engine gears, that we have obtained improved silence by increasing the spiral angle. The spiral angle used on a great number of the U.S.A. cars is 45°. We have never had a case of a gear failure on cars fitted with the 21° spiral angle. Hs.{Lord Ernest Hives - Chair} | ||