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).
Modifications to a dynamo's pole piece to reduce magnetic noise and prepare it for future vehicle series.
| Identifier | ExFiles\Box 168a\3\ img174 | |
| Date | 22th March 1935 | |
| (2) (b) Pole Piece with increased angle of embrace, chamfered tips, and smaller main air gap. It was decided that these improvements could not be considered separately but should come on together. Actually the ventilated dynamo is earmarked for 'K' series but as it will have to run 10,000 miles and must yet be the subject of further alteration, it remains to be seen whether the machine can be cleared in time. As there will be a 20/25 leaving as soon as it can be got ready for a 10,000 mile test to clear smaller road wheels, we should aim at getting the ventilated dynamo on this car with all necessary modifications incorporated. It is complained that the present ventilated dynamo on test is magnetically noisy, and this matter is being dealt with by using thicker armature plates, and finishing the outside diameter after assembly. it will be necessary to carry out this modification as well as fitting the improved pole pieces. With regard to item (2) mentioned at the beginning of the memo, this requires a pole piece having a thinner core to leave room for increasing the field winding so that the resistance of the field can be made adequate for correct working of the vibrator control. The 20/25 machine is the only one that is down on this point as fortunately both the Phantom 2 and the Bentley have sufficient field resistance for this purpose. This complaint is one that requires consideration separately from No.1, and it is rather more urgent as affecting the reliability of the cars we are turning out. Hs{Lord Ernest Hives - Chair}/Wst. has yet to modify and test a machine to confirm the alteration, and until this is done we propose to leave over the question of what recommendations should be made regarding present production. BY/RD. will put in hand enquiries for dies to suit the modified pole proportions. E.{Mr Elliott - Chief Engineer} | ||