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).
Verifying that piston motion is the cause of 25 HP overrun gear rattles by fitting heavier cast iron pistons.
| Identifier | ExFiles\Box 181\M13\M13.2\ img064 | |
| Date | 9th June 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to Sg.{Arthur F. Sidgreaves - MD} Nor. c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to Ey. ORIGINAL Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}5/KT.9.6.31. 25 HP. GEAR RATTLES. X.634. X.5310. Continuing our report Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}1/W.29.5.31. we have been able to verify that the cause of the overrun gear rattle from 30-40 m.p.h. is the piston motion. We have fitted to 12.D.IV. car a set of cast iron pistons weighing 2.7 times the standard aluminium ones. The gear rattle was then very considerably worse and was noticeable with a cold engine and also at full throttle with the ignition off, i.e. under conditions that always previously had eliminated it. We also noticed that the engine was rougher at high speeds with these pistons fitted and shall now carry out tests to find out whether they bring up any flywheel vibration with the lightened flywheel. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||