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).
Design and performance comparison of a launching winch with and without a fluid coupling.
| Identifier | ExFiles\Box 175\2\ img074 | |
| Date | 19th February 1941 | |
| S E C R E T. To Rm.{William Robotham - Chief Engineer} from Ev{Ivan Evernden - coachwork}/DB.{Donald Bastow - Suspensions} c. [REDACTED] Launching Winch. The attached graph gives a comparison between the pull available in the wire of the launching winch with and without fluid coupling fitted. The fluid coupling assumed, is the one recommended by the Hydraulic Coupling & Engineering Co., Ltd., with a stall speed of 865 r.p.m. It will be seen that the difference is at the low speed end only. Below 8½ m.p.h., the clutch curve is indeterminate as no points on the m.e.p., curve are available, but unless the clutch is slipped, it will fall to zero at zero speed. Thus, in the actual get-away from rest, the clutch is at a disadvantage, and if an attempt is made to overcome this by racing the engine before engaging the clutch, then there is danger of an unduly high instantaneous load in the wire. Assumptions made are :- initial drum effective diameter 9¼" increasing progressively to the maximum of 15¼". B.M.E.P. from curve S.87, Ph.lll unit for E.R. Hall, and overall efficiency apart from fluid coupling 93.5% (this gives the pull of 1,000 lbs at 75 m.p.h., with the above power curve). We are proceeding with the design including the fluid coupling, as apart from the advantage in pull in getting away from rest, it makes the handling easier for inexperienced operators. Ev{Ivan Evernden - coachwork}/DB{Donald Bastow - Suspensions} | ||