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 a supplier explaining the cause of a broken cog in a trip mileage counter and the implemented solution.
Identifier | ExFiles\Box 59\2\ Scan403 | |
Date | 9th June 1934 | |
LB. & JJ. 56051. 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. YOUR REF. Hs{Lord Ernest Hives - Chair}/Wst.5/MA. PLEASE QUOTE OUR REF. HRB/B.. CHRONOS WORKS, NORTH CIRCULAR ROAD. LONDON. N.W.2. ALL COMMUNICATIONS TO BE ADDRESSED TO THE COMPANY. Telephone : GLADSTONE 1136 (4 Lines). Telegrams : Aytespeedo, Crickle, London. 9th June, 1934. Messrs. Rolls-Royce Ltd., DERBY. For the attention of Mr. West. Dear Sirs, We duly received your letter of the 6th inst., and the writer confirms his telephone call to Mr. West yesterday afternoon. The cog of the 1/10th disc had broken off, and we have traced this breakage to the fact that, when setting the trip mileage to zero, as you know, the little castle-headed ratchet-wheels allow the discs to go forward in a kind of free-wheel action relative to the main drive. During this trip action, however, the four mileage discs of the trip are allowed to move away from each other a little. This loosening of their positions brings in a risk that, when the drive is again taken up by the car moving, the tooth of the first pinion could ride on to the edge of the cog of the disc, instead of meshing properly, and would inevitably cause the edges of the cog in question to break away on the disc. We have guarded against this matter by bringing in a third bridge to carry the trip mileage in such a way that, when the reset is working, the trip discs are still held perfectly together and not allowed to move sideways. The necessary ratchet movement is taken up on the driving wheel side only. We attach hereto a sketch showing how we have done this, and we must apologize that this matter had escaped our Technical Department's attention when laying out this trip mileage. | ||