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).
Modification to the valves on an S.U. petrol pump to resolve issues with noise and unsteady delivery.
| Identifier | ExFiles\Box 149\4\ scan0133 | |
| Date | 2nd December 1936 | |
| 1263 To E.{Mr Elliott - Chief Engineer} from Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} c. to Hs.{Lord Ernest Hives - Chair} c. to By.{R.W. Bailey - Chief Engineer} d.{John DeLooze - Company Secretary} to Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}16/AP.2.12.36. MODIFICATION TO VALVES ON S.U. PETROL PUMP. Since brass valves were fitted to the pumps there has been a good deal of trouble with valves being noisy, and either one or both sides of the pump not giving a steady delivery. This was found to be due to the suction valve bouncing on its seating. We suggested that the S.U. Company should try a smaller valve lift, this has been reduced from 35 thou. to 25 thou. and the trouble overcome without any reduction in the delivery even in the extreme case of the pump giving a free delivery. This modification is already in Production previous to our ratification, this being the only way they could keep up with our requirements, as we had refused to accept pumps with this fault. The reason for this excessive valve lift, appears to have originated when the springs on the suction valves were removed to increase the delivery of the Bentley pumps, the same valve cage being employed, which allowed the suction valve a 35 thou. lift and this was also adopted when the Phantom III. pump was made. The valves were at the same time changed to Bakelite and though the bouncing may have existed it was not so apparent owing to the lighter valve disc and different material. Also the test rig was not so sensitive and did not show up this fault. All pumps they are modifying and repairing are being sent out with 22 thou. to 25 thou. lift in the suction valve and they have a record of the pumps so treated . We do not feel that we would be justified in recalling all the pumps which went through without this alteration as they were all tested and the small percentage which had this fault returned, in any case it would not mean failure of the pump. Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} | ||