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).
Noisy timing gears on the Wraith engine, discussing potential causes and measurement issues.
| Identifier | ExFiles\Box 136\1\ scan0210 | |
| Date | 14th June 1937 | |
| SECRET. RHC.{R. H. Coverley - Production Engineer} from Rm.{William Robotham - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} c. HPS.{Horace Percy Smith - Experimental Factory Mgr} 115's' Rm{William Robotham - Chief Engineer}5/R.14.6.37. WRAITH TIMING GEAR. As you know the first Wraith engine had very noisy timing gears. There seems to be no fundamental reason why they should be so noisy as we have by now had a considerable amount of experience with fabroil gears on the Bentley and P.III. Hardy has been investigating the job, and attached is his report. His methods of measuring the defects which he quotes are necessarily exceedingly crude, and is is possible, therefore, his figures may not be exactly accurate. We are, however, concerned that there does not appear to be any equipment available for accurately measuring the helix angle of gears in the Factory. We understand from HPS.{Horace Percy Smith - Experimental Factory Mgr} that you have some of this on order. We feel that if we are to get the Wraith timing gear problem licked from the beginning, it is urgent that we should have all the facilities available for measurement. Incidentally, HPS.{Horace Percy Smith - Experimental Factory Mgr} thinks that the parallelism of the camshaft and dynamo pinion axis were checked up when the crankcase was originally machined but the casting was so green they have since gone out of line. If this ageing process is necessary, it would appear rather important to find out exactly what it is worth, and what is to be done to eliminate subsequent distortion. You will remember the trouble we had with the light alloy drum due to the casting growing after being fitted to the car. Rm.{William Robotham - Chief Engineer} | ||