Investigations into oil pressure loss and a malfunctioning petrol gauge.
| Identifier | ExFiles\Box 11\2\ 02-page166 | |
| Date | 6th April 1929 | |
| To HS {Lord Ernest Hives - Chair} and Rm {William Robotham - Chief Engineer} From A.F.F. Handwritten top left: By HS {Lord Ernest Hives - Chair} noted & circled on where we can Hotel de France Chateauroux(French test region) Indre 6/4/29 We have received your letters of the 3/4/29. You will see that investigation work is being carried out irrespective of milage; yesterday the 4th we tackled the oil pressure with a view of decreasing our loss of oil from the rear of engine, also we consider 35 lbs per square inch and over is too high or if it is considered necessary to run at this pressure another gauge is needed on the car. We reduced the pressure to 30 lbs per square inch running at 60 MPH, so far we do not appear to have gained very much, the weather has turned cold, which gives us a better oil consumption in any case therefore results may be misleading. The petrol gauge has not functioned correctly since we landed in France. Its action has been confusing, but we give what is our opinion after carefull examination of the cause of the failure if we take the position as thus, the rear tank full of petrol, the liquid in the gauge tube showing full amount of petrol, we get the following results, there is a definite pressure in the pressure pipe holding the liquid up. In the balance line there is next to nothing We take the car on the road and very quickly obtain a high speed before much petrol is used. a slight surging of the petrol in the tank is caused which causes momentarily a higher pressure in the balance line( which this is important() is still sealed with petrol in the tank) the result being that a certain amount of air in the balance pipe is forced out there being very little weight of petrol to keep it back. The next moment a certain amount of vacuum is produced in the balance line and petrol enters, afterwards it is drawn up the tube by the dropping of the liquid in the gauge, due to petrol being used until as we have found out it mixes with the liquid in the tube. We have found definite proof of this, each time it has been examined. The pressure line has allways been dry the balance line coloured petrol has run out imediatiy it was disconnected from the gauge. Our liqued is now useless as it is 50 % petrol. We hope this is clear to you and should be much obliged if you will send along some more liquid as we intend to carry a junction from the balance line to the top of the filler cap to verify our investigations. A rough sketch herewith to show our meaning. Re the cut out controls. The scheme fitted to 22 EX is not as previously used but we have had the same trouble with the cut out chattering. Handwritten left margin: We do not see what we can do at this stage Handwritten right margin: Amu Stamp: RECEIVED 17 APR 1929 Handwritten signature: Seen A.F.E. | ||
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).