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).
Letter from Hudson Motor Car Company discussing the design and performance of their cork-inserted wet clutch compared to a dry clutch.
| Identifier | ExFiles\Box 129\2\ scan0002 | |
| Date | 19th June 1934 | |
| HUDSON MOTOR CAR COMPANY DETROIT, MICH., U.S.A. CABLE ADDRESS HUDSONCAR June 19, 1934 Mr. W. A.{Mr Adams} Robotham, Rolls-Royce, Limited, Derby. Dear Mr. Robotham: I am glad that you like your Terraplane, and of course, compliments from the Rolls-Royce company carry considerable weight. Your analysis of the clutch corresponds exactly to our feelings in regard to this design. We have used a cork inserted clutch ever since the formation of the company. It was originally a multiple disc design but we have used the single plate design now for six or seven years. We would estimate its life to be about twice that of a dry plate clutch and the service records of parts makers in the United States more than bear out this contention. The only disadvantage we have experienced has been due to the fact we use oil in conjunction with it. As you know, America is a standardized country and with all other manufacturers using a dry plate clutch without exception, there has been some customer resistance to putting oil in the clutch. We have had no resistance to the design from the export field although we ship cars to every corner of the globe and do a relatively large export business. We have always designed and manufactured these clutches ourselves. There are one or two very essential tricks, the principal one being that sufficient space must be provided in the casing outside the O.D. of the plate to accommodate all the oil contained in the clutch. Otherwise the clutch simply will not hold. The surfaces of the flywheel and the pressure plate must be very smooth. Otherwise the surfaces of the clutch will be gradually cut away. The pressures required are somewhat higher than with a dry plate and we have never yet been able to reduce the pressures required to a formula. One of the nice things about this clutch is its extremely light weight and consequent low moment of inertia of the spinning disc. On some of our higher priced models we have made this disc of duralumin, still further reducing the weight and simplifying the problem of gear shifting greatly. | ||