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).
Safety of tyre pumps regarding petrol vapour entering tyres.
| Identifier | ExFiles\Box 149\5\ scan0128 | |
| Date | 31th December 1928 | |
| W/S (Cx{Major Len W. Cox - Advertising Manager}). X993 c. Hs.{Lord Ernest Hives - Chair} ---------- BY3/G.31.12.28. TYRE PUMPS. ---------- Referring to Cx{Major Len W. Cox - Advertising Manager}/Hd{Mr Hayward/Mr Huddy}6/JL.27.12.28. we think it is an oversight to have instructed all the various Depots before referring the matter to Derby. The pump in question was brought to our attention by CWB. in October of this year, the Experimental Department reported on same as per Hs{Lord Ernest Hives - Chair}1/LG.25.10.28., copy attached, from which you will note that the Experimental Department do not consider we should recommend it to RR. owners. If an owner was very keen to fit the pump, then with a note of warning we might let him do so, but to recommend it as you appear to intend to do would in our opinion be a mistake. We do not consider that there will be an entire absence of petrol vapour in the air supplied to the tyres as suggested in their circular, and we say this even although our Experimental Department have not been able to trace petrol in air pumped by the fitting. Our reason for making this statement is that a certain amount of air must find its way through the inlet valve of the cylinder used as the pump. The quantity of air entering by the pump valve and by the inlet valve of the cylinder will be inversely proportional to the pressure at the two points, and since some air must go in through the inlet valve it is difficult to see how petrol vapour can be entirely absent. The fact that there is not a large quantity of petrol vapour present is of course the result of having to run the engine very much throttled down, in fact with the throttle hardly open, but the mixture must be an explosive one, and it would therefore appear certain that petrol vapour must ultimately reach the tyre. BY.{R.W. Bailey - Chief Engineer} | ||