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 supplier A.T. Speedometer Co. Ltd. explaining why magnetic shunts in their speedometers are intentionally not fitted 'dead-tight'.
| Identifier | ExFiles\Box 59\2\ Scan270 | |
| Date | 31th October 1933 | |
| [Handwritten at top: 26051] The A.T. SPEEDOMETER Co., Ltd. MAGNETIC SPEEDOMETERS & Motor Clocks. REVOLUTION INDICATORS FOR MOTOR CARS, MOTOR BOATS, AND ENGINES, MILEAGE RECORDERS, ETC. DIRECTORS. W. Henderson-Cleland. A.{Mr Adams} Gordon Smith. H.{Arthur M. Hanbury - Head Complaints} R.{Sir Henry Royce} Buckland. CHRONOS WORKS, NORTH CIRCULAR ROAD. LONDON. N.W.2. Telephone: GLADSTONE 1136 (4 Lines). Telegrams: Aytespeedo, Crickle, London. YOUR REF. Hs{Lord Ernest Hives - Chair}/Wst.6/MA. PLEASE QUOTE OUR REF. HRB/B....... ALL COMMUNICATIONS TO BE ADDRESSED TO THE COMPANY. [Handwritten in center: WST] 31st October, 1933. Messrs. Rolls-Royce Ltd., DERBY. For the attention of Mr. West. Dear Sirs, In answer to your favour of the 26th inst., we note that you feel that the magnetic shunts in the speedometers are loose. We would, however, like to point out that, up to now, we have not known of a single instance of these shunts moving after instruments have been delivered. They are fitted in a manner, whereby they are not dead-tight, because, as you know, we use this movement to effect final adjustments on the timing of the speed mechanism. If we have to tighten them up dead-hard, the difficulty is that there is a tendency for the shunt to move with the last few millemetres of the tightening-up process. We would point out that there is a spring-washer used under the shunt. We will, however, give very special and careful attention to get this shunt as tight as possible, consistent with it not moving round. We trust sincerely that this explanation will be acceptable to you. [Handwritten at bottom:] X Mr. Manwaring will also discuss this little matter with you HRB | ||