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).
Engine gear rattle on Bentley and 20/25 models, detailing investigations and potential solutions.
| Identifier | ExFiles\Box 136\1\ scan0070 | |
| Date | 2nd August 1933 | |
| Seat 52 LBS x'd Valve Area 1.75D Fullyt- 92-7# Exhaust Pr.{Percy H. Rose} 73 LBS/D" E.13/HP.2.8.33. Exhaust Valve Load 110LBS To WOR.{Arthur Wormald - General Works Manager} from E.{Mr Elliott - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} EP.{G. Eric Platford - Chief Quality Engineer} Mx.{John H Maddocks - Chief Proving Officer} 40-23 } 860x } Reduced running light by 80% re Engine Gear Rattles - Bentley and 20/25. Regarding the above, we have just been out on a demonstration run with EP.{G. Eric Platford - Chief Quality Engineer} on a Bentley chassis, and have been truly astonished at the noise emanating from the timing gears when accelerating against load, either on the gears or direct drive which reaches a maximum at a speed of 800 r.p.m. and anything done to smooth off the engine, such as retarding the spark or closing the throttle has an immediate and beneficial effect. Hitherto our attention has been directed to the rattle which occurs with the engine running light about 700 r.p.m. for which the following experimental designs have been issued, and which rattle is due to the camshaft. 3½ litre Bentley: Balancing Cam - LeC.3543 and 3563. 8/7/33. Timing Wheel Brake - LeC. 3577. 19/7/33. Fabroil Gear. - LeC. 3553 and 3532. 22/6/33. We are now issuing at the earliest possible moment for experimental trial a modification to the crankshaft pinion drive as it is evident that the source of this noise on the road from these high compression engines is almost entirely from the movement of the front end of the crankshaft. I understand from EP.{G. Eric Platford - Chief Quality Engineer} that the same effect can be demonstrated on the 20/25 chassis but of less intensity due to the lower compression and power of the engine. Cholmondeley's Car. C.F.T.43 E.{Mr Elliott - Chief Engineer} 100/us | ||