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 to A.T. Speedometer Co. Ltd. regarding loose magnetic shunts on Bentley chassis instruments causing false calibration.
| Identifier | ExFiles\Box 59\2\ Scan269 | |
| Date | 26th October 1933 | |
| 66081 Hs{Lord Ernest Hives - Chair}/Wst.6/MA. 26th October, 1933. The A.T.Speedometer Co.Ltd., Chronos Works, North Circular Road, London, N.W.2. For the attention of Mr.H.R.Buckland. Dear Sir, We have noticed on the A.T.Instrument fitted to the Bentley chassis that the magnetic shunts used for the purpose of calibration are loose. In some instruments they are properly tightened but in others they can be moved quite easily with a pencil. We feel we must insist on these shunts being absolutely tight when sent away from your Works because we are afraid that the vibration of the chassis will cause these shunts to move thus giving a false calibration. In fact we have a case on record on the Bentley chassis where a speedometer was correctly calibrated when sent out from our Works but when subsequently tried on the road and on the track gave a far different reading a circumstance which at the time we were unable to satisfactorily explain. It would appear that on this particular instrument the magnetic shunt may have moved altering the calibration. We should like you to give this your immediate attention and advise us what you propose to do in the matter. With reference to the new lightened type instruments we should like to know from you when you propose to visit us for the purpose of bringing these instruments along for our test. No doubt you will appreciate that the matter is extremely urgent. Yours faithfully, FOR ROLLS-ROYCE LIMITED. | ||