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).
Speedometer drive cable standards, fracture issues, and fitting improvements.
| Identifier | ExFiles\Box 33\4\ Scan028 | |
| Date | 20th May 1927 | |
| X1756 E (WW) c.HS.{Lord Ernest Hives - Chair} BY12/H.{Arthur M. Hanbury - Head Complaints} 20.5.27. SPEEDOMETER DRIVE. ---------------- Referring to E2/M.14.5.27. the only standard form of driving end for a speedometer cable is that we specify on our drawing, .140 square. We have written the B.E.S.A. people on the strength of your letter, but they reply they are unable to assist us in this matter, as there is no B.E.S.A. specification dealing with the subject. Since all aero parts as well as chassis, use the .140 square end, it would appear that there is some mistake in the information supplied to you. We have had one or two cases submitted to us of fractures like those you refer to, but we were able to demonstrate to the Smith people, who were responsible for fitting the little gear box, that the cable end carrying the square was not running true with the hole into which it fitted. As a result of this, they are now fitting a universal jointed piece, which we think should overcome the trouble. In our opinion, it was not due to sudden changes in the speedometer flex curvature, but poor fitting in the first place. So far as I am aware, we are not particularly recommending the mechanical wiper from this end. Possibly Sales are more interested in it than we are, but we think the improvement we have insisted upon having incorporated will materially affect the trouble referred to. BY.{R.W. Bailey - Chief Engineer} DERBY ROLLS-ROYCE LIMITED | ||