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).
Issues with Bentley petrol pumps and a comparative analysis with A.C. pumps following a visit to their works.
| Identifier | ExFiles\Box 27a\2\ Scan216 | |
| Date | 26th July 1933 | |
| File x2677 To S.G. from Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} Box Date By Ha/Lid.{A. J. Lidsey}3/KT.26.7.33. BENTLEY - PETROL PUMPS. In connection with troubles experienced on the mechanical petrol pump as fitted to the Bentley chassis, we have paid a visit to the A.C. works in Birmingham. (Our pump is of course made under A.C. patents). The chief trouble with our pump is that it will not deliver the quantity of petrol we require at as low a pressure as the A.C. pump. In order to increase the flow we have had to put up the pressure; this has a detrimental effect on the carburation. The maximum pressure reached on any A.C. pump is 3.25 lbs/sq.in. whereas on the Bentley we go up to 5 lbs/sq.in. The A.C. people placed all their knowledge at our disposal and put forward the following possible reasons why our pump is not as good as theirs, (1) The volume of the chambers above and below the diaphragm is, they say, not large enough. (It is considerably less than on their smaller size pump). This point they say is probably the major reason for the inefficiency of our pump. (2) Larger/diaphragm washers will probably be advantageous; they are at the moment endurance testing several pumps with larger diameter washers than they use at present, before putting them into production. The larger washers increase the petrol delivery. The washers on their pump are already larger than ours in spite of the fact that our diaphragm is larger in diameter. (3) They think the diaphragm "plunger" on our pump has too little clearance in its guide. They experienced a lot of trouble on their own pumps from this cause when they first put them on the market, and they now have approx. .050" diametral clearance between the "plunger" and its guide. The trouble experienced due to this is poor delivery at high speeds. The above three points appear to be well worth while investigating. Other points discussed which are worth recording are as follows :- Diaphragm Fitting. When erecting the pump it is very important to | ||