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).
Relief valve design and placement to manage tank pressure and prevent breakdowns.
| Identifier | ExFiles\Box 37\4\ scan 077 | |
| Date | 9th August 1917 | |
| R.R.Contd: S.D. 442, 9-8-17; G 1985. (2) of more in order to get 4 lbs. pressure in the tank. This is because of the skin friction of air and probably drops of oil in the delivery pipe to the tank. The new arrangement will obviate this difficulty and will also guarantee that the relief valve fitted to the petrol tank is of a rational design. We understand that breakdowns have occurred which have been ascribed to the engine, but which have actually been due to badly designed relief valves fitted by the 'plane makers. A drawing of the relief valve follows immediately. I have shown the delivery valve of the pump facing upwards. This is in order to get the air pipe into the cylinder head at the bottom, so that any oil is immediately discharged into the delivery valve. We might try the valve pointing downwards if such a position would be more convenient, but we are afraid we might get oil hammer in this case. We do not like the idea of a valve inclined or horizontal, because of the weight of the valve tending to wear the guides though I believe the valve actually works in this position in practice quite satisfactorily on the present air pump on camshaft casing which is more often than not set in an inclined or horizontal position. OY. | ||