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).
Comparing the oil feed to the Bentley valve mechanism with the 20/25 HP model.
| Identifier | ExFiles\Box 88\4\ scan0043 | |
| Date | 20th February 1934 | |
| To Sg.{Arthur F. Sidgreaves - MD} From Hs{Lord Ernest Hives - Chair}/Wths. X 254 Hs{Lord Ernest Hives - Chair}/Wths.5/RW. 20.2.34. c.c. to Wor.{Arthur Wormald - General Works Manager} c.c. to L. c.c. to By.{R.W. Bailey - Chief Engineer} c.c. to CR.{Mr Cra???ster / Mr Chichester} c.c. to LE. c.c. to HN.{F. C. Honeyman - Retail orders} OIL FEED TO BENTLEY VALVE MECHANISM. The Test Dept. have recently complained that the oil feed to the Valve Mechanism on Bentley units is by no means as good as on 20/25 HP. The main fault with the Bentley Oil Feed is that on first starting up a considerable time elapses (approximately 15-20 minutes) before any oil starts to run down the push rods; the tappets of course rely upon the oil that runs down the push rods for their lubrication. Under similar conditions on the 20/25 HP. oil starts to run down the push rods after approximately one minute from the time of starting up. The method of supplying the oil to the Valve mechanism on Bentley varies from that used on the 20/25 HP. inasmuch as there is only a single feed on Bentley at the centre of the rocker shaft, whereas on the 20/25 there is a feed at each end of the rocker shaft. This variation in design has, however, no effect on the oil supply, since the same amount of oil is supplied to the Valve Mechanism in each case. This is obvious since the oil pump and relief valve are identical in each case, the oil feed to the engine gears is exactly similar on the two units, and since the same diameter pipe is used to feed the Valve mechanism, then the amount of oil must be the same in each case. We definitely established the fact that plenty of oil is available on the Bentley and in fact the rocker shaft has a plentiful supply of oil; this was observed on an engine which was very slow in showing oil to the push rods by undoing one of the nuts holding down the rocker shaft. The only difference left in the design is the number and positioning of the rocker oil supply holes. The Bentley has two holes to each rocker but the 20/25 HP. has three holes. Two of the holes on the 20/25 however coincide with the annular groove formed between the ends of the rocker bushes so that the oil supply is not restricted in any way to the push rods. | ||