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).
Investigation into failures of the Autovac petrol feed system due to leaking floats.
| Identifier | ExFiles\Box 40\4\ Scan335 | |
| Date | 1st May 1930 | |
| To R.{Sir Henry Royce} (Held up) From Hs{Lord Ernest Hives - Chair}/AJL. *3579. Hs{Lord Ernest Hives - Chair}/AJL.1/MJ.1.5.30. c. to SG.{Arthur F. Sidgreaves - MD} WDP. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ SECRETARY _ _ _ _ _ _ _ _ _ _ c. to E.{Mr Elliott - Chief Engineer} DS. c. to EV.{Ivan Evernden - coachwork} MX.{John H Maddocks - Chief Proving Officer} _ _ _ _ _ _ _ _ _ _ AUTOVAC PETROL FEED. ==================== In every case but two in which Autovac tanks have failed it has been found that the floats were leaking at the joint, mainly due to the faulty soldering. Owing to the action of the self draining float it has been difficult to see how this failure has come about. Tests we have carried out shew that this failure is due to a temperature effect, and that the self-draining float will work unfailingly if the petrol is cold, no matter how large the leak is at the bottom of the float. It was suggested that the joint in the float should be made at the top, this has however been proved to be fatal should a leak occur at the joint. The conclusions arrived at are:- (1) The joint at the bottom of the float is correct, but the manufacturers must make a better job of the joint than previously. (2) The effect of an Autovac failure is much more serious on P.II than on cars using the induction pipe depression. The crankcase can be filled with petrol before any sign of failure is apparent to the driver. When induction pipe suction is utilised, the engine stops immediately the Autovac fails. (3) A different design of float is necessary which | ||