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).
The examination of a failed S.U. petrol pump from chassis 3.AZ.196 which failed in Germany.
| Identifier | ExFiles\Box 149\4\ scan0225 | |
| Date | 7th April 1937 | |
| 1263 Hs.{Lord Ernest Hives - Chair} from Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} c. Sg.{Arthur F. Sidgreaves - MD} c. Hd.{Mr Hayward/Mr Huddy} REPORT ON THE EXAMINATION OF THE S.U. PETROL PUMP OFF CHASSIS 3.AZ.196 WHICH FAILED IN GERMANY. The pump was tried as received on the Test Department rig where it was found that the N.S. unit refused to operate. The off-side unit at first pumped satisfactorily but suddenly stopped. I took the pump over to the S.U. Co. and examined it in their presence. The Near side unit - Marks on the near side unit showed it had been taken down and re-assembled when the diaphragm had not been set to give sufficient movement to throw over the toggle mechanism and brake the contacts. On detailed examination it was found that the centre recess in the armature had at some time been fouling the pole piece of the magneto and an effort had been made to file this to clear. The diaphragm material was good. We consider this unit failed originally owing to this fouling, it had then been taken down, and if it had been cleared and set correctly would have continued to run. The off-side unit did not show any signs of the magnet pot having been disturbed, though the toggle mechanism was set with only half the clearance normally given to break the points, but this may have been due to the contact blade having been dismantled and re-assembled without disturbing the magnet pot. The diaphragm was in good condition and the armature had not in this case been fouling. When the valves were examined the nearside were correct, but the offside had been disturbed and the circlip retaining the delivery valve had been bent so that it did not spring out into the locating recess and was lying loose on top of the valve disc. This explains the sudden failure of the offside unit which at times gave a full delivery, but became jammed by the loose circlip and stopped the pump. The S.U. Co. were unable to deny that the first cause of failure was due to their bad workmanship in the N. side unit. This lack of concentricity of the pole piece in the magnet pot was brought to their notice by me in the beginning of January this year, and they agreed to look into the matter and have a gauge made to check this, and during my last visit there a month ago they were doing this on all our pumps. continued | ||