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).
Page 2 of a letter detailing belt performance tests and comparisons with other automotive companies.
| Identifier | ExFiles\Box 135\1\ scan0230 | |
| Date | 27th October 1938 guessed | |
| Rolls-Royce, Limited. Page 2 the belt. I am sorry that I can't give you a very definite answer to your question about the difference in fan horse power between rig tests and road conditions. We have no accurate data on this because, in nearly every case, conditions vary. However, we do know that there is an actual difference although it is not very large. In low, or first gear, road and rig conditions are almost exactly alike. At higher speeds, however, road conditions are slightly easier on a belt than bench conditions. Incidentally, our Engineering Department is rather curious as to how you determined there was 27 H.P. pull on this belt. Although you have given us this figure, they felt that it would be almost an impossibility to transmit that much power, under the conditions set down, over 3.875 inch pulleys. We would certainly appreciate any information that you could give us on this point. You were certainly right, Mr. Steadman, in remarking that 11-3/4 hours running time on this application does not sound very impressive alongside the 387 hour test for the Massey Harris belt. However, the conditions on the Massey Harris drive were considerably different. It too was a tough drive, but as we have found so many times, each set of conditions, on each problem, seems to vary from the one before it. Here are some results that we have achieved for various automotive companies in the United States. As you will notice, even our original and poorest attempt still exceeded our first attempt for you. Nevertheless in each case we succeeded in whipping the problem and proving the belt, and we are confident we can do the same for you. For the Chrysler Corporation of Detroit, Michigan our first belt ran only 50 hours. Further work brought it up to 60, then 100, and finally 290 hours. Our first sample belt for General Motors Truck Corporation also of Detroit ran 110 hours. The final effort brought the belt life up to 420 hours. The first refrigerator belt we made for the Nash-Kelvinator Corporation of Detroit ran only 400 hours. Further work advanced the belt life up to 500 hours, then 700, then 900, and finally 1200 hours, an all time record. No other belt manufacturing company has been able to come within 300 hours of this latter amount. Not one of those problems represented anything quite as tough as the proposition you have given us. But, in each case we did show a real improvement. We want very much to do that sort of development work for you. | ||