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).
Timing gears, dampers, and camshaft thrust issues in B.60 and B.80 engines.
| Identifier | ExFiles\Box 109\4\ scan0105 | |
| Date | 29th June 1939 | |
| -5- Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}2/MH.{M. Huckerby}29.6.39. TIMING GEARS & DAMPER. The timing gears without exception have on all the B.60 and B.80 units been free from both rattle and whine and no attention has been necessary. No crankshaft periods could be detected with the adapted Studebaker damper, which damper has served us admirably in the development of our engine, having completed 30 hours' endurance on the B.60 and similar time of endurance on the B.80 and now fitted for a 30,000 miles test. In consequence two more similar dampers are being produced, as at present other than the Wraith adapted type there is no other damper available that will mechanically stand up to the job. During a recent investigation of camshaft oscillations we were surprised to find that at speeds in excess of 2500 R.P.M. the camshaft came forward, due presumably to the forward thrust of the oil pump and distributor drive gear exceeding the rear thrust of the helical tooth camwheel. This means that the thrust plunger has to take the forward thrust at high speeds. At present the details allow a liberal end float, but in view of the above, this we consider should be cut down to .004-.006. Actually, after the 50 hours' endurance run on the B.80 very little wear had taken place on the plunger which appears to withstand the loading; however, the 30,000 miles run on 30.G.VII will show whether it is necessary to provide a larger thrust or not. In the chain drive arrangement on B.60 where no rear thrust is available, the thrust throughout will be forward whereas the camshaft thrust face is designed for a rear thrust. The chain drive in itself is an unknown quantity, therefore we do not consider any design action is necessary until the chain has been run. As previously reported, the ignition advance on these units has been 4-6° short of range as set in the Laboratory, and although not yet proved we are fairly certain that this forward movement of the camshaft thus rotationally retarding the distributor drive gear is responsible. | ||