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 the Phantom III speedometer drive running dry and the proposed modifications to resolve the issue.
| Identifier | ExFiles\Box 165\4\ img365 | |
| Date | 15th May 1936 | |
| 86065. To R.{Sir Henry Royce} c. to Wor.{Arthur Wormald - General Works Manager} c. to Hy.{Tom Haldenby - Plant Engineer} c. to Ds. c. to Edy. c. to MX.{John H Maddocks - Chief Proving Officer} c. to RHC.{R. H. Coverley - Production Engineer} Phantom III Speedometer Drive. We have been investigating the trouble experienced on production Ph.III chassis of the speedometer drive running dry. We find that with the present standard arrangement oil reaches the speedometer drive only when the oil is above 90°C., and at propellor shaft speeds in excess of 3,000 r.p.m. Under these conditions oil occasionally splashes up through the drain oil. This fault has not made itself apparent on experimental gearboxes as these do not have prolonged running at low speeds as occurs on the production dynamometer. In order to overcome this trouble we have tried a 0.187" dia. oil feed hole as shown on the attached Rn.{Mr Robinson}137. This catches oil thrown up by the second speed gears and gives a reliable supply above 1000 r.p.m. and 50°C. In order to provide adequate drainage at high speeds and temperatures it is necessary to drill an additional drain hole also shown on Rn.{Mr Robinson}137. We have tested this arrangement up to speeds corresponding to 80 m.p.h. and at temperatures up to 100°C. to determine whether any oil leaks are caused by the increased supply of oil, and the results are perfectly satisfactory. We recommend that the modifications shown on Rn.{Mr Robinson}137 should be carried out on all production chassis before they leave the Works. Both the additional holes can be drilled with the gearbox in position in the chassis although it may be necessary to remove one stud in order to drill the extra drain hole. Rs{Sir Henry Royce's Secretary}/P.J.Hardy. | ||