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).
Theoretical calculations and road test results for a J.3. crankshaft.
| Identifier | ExFiles\Box 103\3\ scan0174 | |
| Date | 9th May 1933 | |
| X5010 To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}4/KT.9.5.33. J.3. CRANKSHAFT. As requested we have calculated the theoretical gain in critical speed when using the 2.750 journal crankshaft to Lec.3193 instead of E.57280. The stiffness is increased from 59000 to 69000 lbs.ft/radian. Allowing for the slight increase in inertia of the wider webs this should raise the master period by about 7½%. Increasing the crankpin diameter from 2.125 to 2.250 would give approximately a further 2½% gain. We would also refer you to Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}13/MA.21.11.32. for further particulars of the behaviour of the J.3. crankshaft. All our crankshafts so far have had 12 balance weights to the Chrysler scheme. Road tests on 1.J.3. car show that the frings of the master period begins at 3900 r.p.m. equivalent to 83 m.p.h. 4100 r.p.m. was attained in 3rd gear at which speed the damper was having to work hard. The engine although very noisy was not very rough. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||