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).
Cause and proposed solution for a camshaft squawk on the Phantom II engine.
| Identifier | ExFiles\Box 13\2\ 02-page170 | |
| Date | 9th October 1933 | |
| Rm{William Robotham - Chief Engineer} x7090 To WOR.{Arthur Wormald - General Works Manager} from E.{Mr Elliott - Chief Engineer} E.7/HP.9.10.33. c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Sft.{Mr Swift} Mx.{John H Maddocks - Chief Proving Officer} EP.{G. Eric Platford - Chief Quality Engineer} Hd.{Mr Hayward/Mr Huddy} x670t. re Camshaft Squawk on P.II. We have issued some roller tappets on the engine for the Vulture chassis to LeG.3664 in place of the rubbers, and this we have reason to believe will cure the camshaft squawk. This squawk has always been a feature of the P.II engine and occurs at the moment when Nos. 10 and 12 tappets are lifted, which happens simultaneously. It appears to be due to a torsional chatter set up in the camshaft and involving the inertia of the moving parts of the valve gear, the valve spring load, and the momentary changes of friction which occur between the cam, the tappet and its guide. The trouble can be apparently cured by improving the lubrication or by using a roller type of tappet as fitted to the 20/25. As we found it was practically impossible to arrange any form of oil bath around the camshaft we are adopting the latter policy. The reduction in the virtual diameter of the tappet roller diameter from 1.75 to 1 inch calls for a new cam form to avoid any loss of power due to the effect on the valve lift curve, but this loss may be found to be negligible in practice. A test should be made with the existing camshaft for power, and floating speed in case it is required to fit roller tappets to any existing engines. E.{Mr Elliott - Chief Engineer} | ||