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 discussing steering performance issues, including temperature, friction, and component manufacturing.
| Identifier | ExFiles\Box 154\3\ scan0040 | |
| Date | 20th September 1927 | |
| ROLLS-ROYCE OF AMERICA, INC. SPRINGFIELD, MASS. Oy18-E-92027 September 20, 1927. Mr. Robotham, Rolls-Royce Ltd. Derby, England. Dear Mr. Robotham: Re Steering Mr. Caswell informs me that by running with an accurate distance-reading thermometer in the steering box in warm weather, he has recorded temperatures as high as 150° F.{Mr Friese} - 65° C. This was after fifty miles running in fairly warm weather. It is probably safe to assume that in real hot weather and prolonged running we may get as high as 160° F.{Mr Friese} It does not seem to me that this slight divergency in temperature can account for the vast difference in performance of the steerings. I have already sent you the result of a test on hot concrete which goes to show that the friction between tire and road does not increase greatly in hot weather. Prolonged inspection has failed to show that our steering worms are in any way inferior to the Derby worms in accuracy. In fact the method of grinding on the Pratt and Whitney which indexes by means of the feed gearing so that all threads are ground in turn, is bound to give more accurate spacing of the three pitches, and we actually find that after burnishing a worm can be engaged with its nut equally well in any of the three threads. I am now asking Mr. Caswell and Mr. Allen to go more deeply into the question of surface hardness, both of the worm threads and the white metal. Earlier experience on the Silver Ghost, where the steering with 6-3/4" tires was changed from a failure to a success, simply by hardening the worm without subsequent grinding, goes to prove the vast importance of this point. Yours very truly, Maurice Olley | ||