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 discussing riding quality, the effect of drilled valves, and shock absorber settings.
| Identifier | ExFiles\Box 55\4\ Scan346 | |
| Date | 11th April 1929 | |
| ROLLS-ROYCE OF AMERICA, INC. SPRINGFIELD, MASS. X235 OY2 April 11th, 1929. Mr. Robotham, Rolls Royce Ltd., Derby, England. Dear Mr. Robotham: Re RIDING QUALITY Thank you for your note HsRm1.LG28.3.29 on the effect of drilled valves on the S.S. and also for HsRm2.LG26.10.28 on the actual pictures of the rear axle and rear body movement. I think if you will compare the latter with OY3 July 13/28 you will agree that the figures we gave therein for the four fundamental movements of pitching, bouncing and the two axle movements (obtained by observation and by timing with a watch held to the ear) came pretty close to the facts at least as regards the rear axle. In view of what you have proved by the axle test and indicator diagrams I cannot understand how drilled valves at the rear of the S.S. could possibly interfere with the rear seat riding or with the road-holding quality at speed, so long at least as the poundage of the valves was increased so that the increase in height of the indicator diagram could roughly compensate for its more triangular form. We now set our shock absorbers :- Axle Control. 120 lb. up and down. Valves. Standard A-12293 Alternative A-12294 (tight) " A-12217 (free ) Rear 60 lb. up 120 lb. down Valves. Standard A-12306 Alternative A-12217 (tight) A-12180 (free ) -continued- | ||