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).
Investigation into a slipping trouble on the 20 HP starter motor, caused by a worn cork washer.
| Identifier | ExFiles\Box 40\5\ Scan194 | |
| Date | 29th September 1927 | |
| To BY.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} c. to Hs.{Lord Ernest Hives - Chair} (X3587) Hs{Lord Ernest Hives - Chair}/GWH{George W. Hancock - Head Chateauroux}/LG29.9.27. X3587 Y5650 20 HP. STARTER MOTOR. We have been investigating a slipping trouble that arises after the starter motor has been in use some time, or when a thin cork washer is fitted. We find this occurs when the cork washer has worn from .1875" to approx .100" thickness. The slipping occurs when the operating sleeve has wound up to the strong inner spring, but has not started to compress it. Upon investigating the cause we find that when a new cork washer is fitted having a thickness of .1875" we get a surface friction which we were unaware of on the operating sleeve which is sufficient to make the sleeve wind right up thereby getting the maximum friction on the cork washer when no slipping occurs. This extra friction is got by the end cap D.50872 pressing the inner washer D.51385 on to the face of the operating sleeve, due to actually insufficient end clearance for the cap to be locked up by spring ring. When the cork has worn this pressure is relieved thereby relieving the extra friction on the operating sleeve which is then insufficient to wind up the inner spring and slipping occurs. It clearly points out that it is necessary to have more friction area on the operating sleeve and we suggest that a design be got out whereby we could definitely make use of the extra friction. Hs{Lord Ernest Hives - Chair}/G.W.Hancock. | ||