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).
Letter from an omnibus company regarding their experience with dynamo commutator sparking at high speeds.
| Identifier | ExFiles\Box 60\3\ Scan218 | |
| Date | 21th March 1933 | |
| Form 171A. x6092 .4800 TELEPHONE: CHELMSFORD 1031. TELEGRAMS: NATIONAL CHELMSFORD. THE EASTERN NATIONAL OMNIBUS CO., LTD. HEAD OFFICE: NEW WRITTLE STREET CHELMSFORD. DIRECTORS: F.{Mr Friese} P. ARNOLD. C.V.O., C.B.E. JOHN F.{Mr Friese} HEATON. SIR JOHN JARVIS, BT.{Capt. J. S. Burt - Engineer}, CHAIRMAN. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} CARDWELL. J.{Mr Johnson W.M.} H.{Arthur M. Hanbury - Head Complaints} FOLLOWS. C.B.E., M.V.O. W. J.{Mr Johnson W.M.} IDEN. C. J.{Mr Johnson W.M.} SELWAY, C.B.E. B. SMITH. H.{Arthur M. Hanbury - Head Complaints} L. THORNHILL. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} F.{Mr Friese} THURSTON. CHIEF DEPOTS: BEDFORD CHELMSFORD CLACTON COLCHESTER DOVERCOURT DUNSTABLE GRAYS HARWICH HUNTINGDON LUTON STONY STRATFORD WALTON-ON-NAZE ENGINEER'S OFFICE. ANCHOR WORKS, CHELMSFORD. WJM/MLL. Your ref:- Hs{Lord Ernest Hives - Chair}/Wst.3/MA. March 21st, 1933. Messrs.Rolls-Royce, Ltd. DERBY. Dear Sirs, For the attention of Mr.H.E.West. We note from yours of the 17th inst, that you have been experimenting with Constant Voltage Dynamos and that one of the troubles you have experienced is sparking on the commutator with full load, at high speeds. On the machines we have operating in our fleet we do not appear to have experienced this trouble, and we think that had there been any appreciable amount of sparking, it would have reflected itself in abnormal wear of brushes, whereas the number of brushes replaced has been practically nil. It is of course true that our machines would not be called upon to run at the speeds which are reached with private cars, and it may of course be that if the top speed of our machines was increased, the trouble you mention might be experienced. We fitted Mr.Iden's Phanton R.R.car with a Bosch Constant Voltage Dynamo, type RK130/12, and the brushes of this have, we understand, never been adjusted or renewed. The car has been driven at fast speeds for long distances and we think that had there been any sparking trouble, it would have been noticed and attention to the | ||