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).
Tests conducted on 20 HP crankshafts.
| Identifier | ExFiles\Box 74\3\ scan0301 | |
| Date | 23th December 1924 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF. HS{Lord Ernest Hives - Chair}/TMW/LG23.12.24. 20 HP. CRANKSHAFTS. Up to date, the following experimental tests have been carried out on Crankshafts. A strengthened type of shaft has been tried in 4-G-11, and compared with a standard shaft in 7-G-11. The std. shaft in 7-G-11 was removed and a disc shaft fitted instead. It will be necessary to fit a strengthened shaft in 7-G-11 to obtain accurate comparisons. The shafts are compared under the following conditions :- Test. Running in 2nd. speed full power up to 45 m.p.h. or 3570 r.p.m., then slowing down, throttle closed. (a) Car towed in 1st. speed up to 23 m.p.h. or 3600 r.p.m., throttle closed. (b) As (a) but throttle open. At low speeds there are practically no vibrations under any condition on shaft to be noted, but at high speeds the shafts have different characteristics which are given below :- Test 1. 4-G-11 - Strengthened type shaft. Very good at all speeds both forward and retarding. Only very slight vibrations felt under any condition. 7-G-11 - standard shaft. A vibratory period is felt from 39 to 41 m.p.h., after which the engine is still rough. Retarding the engine is generally rough from the maximum speed down to 33 m.p.h. contd :- | ||