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).
Car components including pistons, clutch, bearings, electrical systems, and brakes.
| Identifier | ExFiles\Box 173\1\ img315 | |
| Date | 23th January 1934 guessed | |
| -2- Other details of the car of interest are BOHN ALUMINUM PISTON OF ALUMILITE WT. Bare 12 1/2 oz. treated by the new oxidizing process, i.e. placed in a solution of (Oxalic Acid) } 35-40 min. (H2SO4) } at 80oC (H2O) } and subjected to a reverse plating current. This is the same piston that Cadillacs have adopted and all speak highly of this facing process which obviates scuffing and the necessity for much running in. I will get a set made to suit the Bentley and bring them back with me. SINGLE PLATE CLUTCH The fit a long clutch. Howe gone back to a single plate after having used a double plate. They like the single plate much better for smoothness of engagement and gear change. The change has been made possible by improved mechanical efficiency of clutch gear. Figures they gave me were: Separation of plate 3/16" Pedal Travel to obtain - 2-3/8" Spring Pressure - 1800 lbs. 12 springs 6 fingers These figures do not seem very convincing and as it was brought out as a complete unit they did not know much about it. I measured the friction disc, however, fabric on the driven member. Inside dia. 7.00" Outside " 11.875" In the car the clutch pedal travel feels more like 4". I will try and get the clutch makers figures and those of Cadillac. A spring damped clutch centre is incorporated. BEARINGS Lead bronze throughout. Bohn manufacture. They have not been able to get away with strip bearings made at Cleveland. Limit oil inlet to bearings to 220°F.{Mr Friese} They use a Harrison oil cooler fitted on the suction side of the pump. ELECTRICAL Two coils and contact breakers, on distributor. Dynamo - 8 1/4"x 5" Starter - 9 1/4 x 5 1/2" geared down on flywheel only 11.6-1 Carb. - Stromburg down draught A.C. Cleaner & silencer Valves - Tungsten inserts "frozen" in Steering - Marles type - 16-1 ratio Brakes - Bendix with B.K. Vacuum booster. Very efficient even without booster. Petrol Pump - A.C. large size fitted to front end of timing case | ||