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 and faults found in an S.U. Petrol Pump from chassis 3-AZ-63.
| Identifier | ExFiles\Box 149\4\ scan0323 | |
| Date | 5th June 1937 | |
| To Rm.{William Robotham - Chief Engineer} c. to Hd.{Mr Hayward/Mr Huddy} 1263 Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}1/JH.5.6.37. Report on S.U. Petrol Pump off chassis 3-AZ-63 - Scott Mason. I examined this pump at the S.U. works. When first received it would work normally on both sides down to 6 volts. After a short period the off side unit stuck and the near side unit also did no momentarily. The Off side unit. The setting of the pump was two holes short, that is 2 holes back against the 4 normally used. The toggle mechanism was free and the points clean and not burnt. There were five separate score marks on the inside of the magnet pot and the pole piece was .006" out of centre. The distance pieces had worn in some cases .002" below the top limit size as fitted. The reason for this wear being the eccentricity of the pole piece.We consider the failure on this side due to a small piece of foreign matter which has either got in through the vent hole or got in when the pump was assembled and owing to the small clearance left between the armature and the body caused sticking. The magnet unit also showed signs of having been stuck for a considerable time and having overheated. In the near side unit the points were black and showed considerably more wear than the off side unit. The setting was also two holes short. On further examination the armature had been fouling the side though it was only possible to measure .002" wear on the rollers. The pole piece being .006" out of centre. We checked up all the dimensions on the pump with the S.U. gauges and found them correct. As this small amount of wear on the rollers did not justify the armature fouling the pot, I carried out a thorough investigation and found a tool mark on the outside roller race which a measurement was .003" deep. As this groove was larger than the normal diameter and did not extend more than 1/8 of an inch round the circumference it would escape detection with a plug gauge. This .003" together with the .002" wear on the rollers would be sufficient to cause fouling. Here again the eccentric pole piece is responsible. This has previously been reported on and steps taken to prevent this faulty assembly. | ||