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).
Methodology and results of clutch tests for 20/25 and Bentley models.
| Identifier | ExFiles\Box 85\2\ scan0080 | |
| Date | 3rd May 1934 | |
| Ha/PJH.20/KW.3.5.34. 20/25 AND BENTLEY CLUTCH TESTS. We have recently carried out tests on the test bed on the new type of 20/25 HP. clutch to N.Sch.3948 and G.56674, to determine the rate of lining wear and whether there was any tendency to slip due to picking up on the splines when hot. The method of carrying out clutch tests on the test bed is as follows :- The engine to which the clutch is fitted is run at 2000 r.p.m. full throttle. The clutch is disengaged sharply, thus allowing the engine speed to race up. When the speed reaches 3000 r.p.m. the clutch is re-engaged sharply so that the clutch slips until the engine speed drops to 2000 r.p.m. The clutch is subjected to 260 of these slips in batches of 20. The average rate of slipping is 80 per hour. At every 20th slip the wear of both linings is measured by the distance between a fixed stop and a lever on the clutch withdrawl shaft. The wear is magnified 17.6 times. At the completion of the above 260 slips the conditions are made much more severe. The engine is run at 500 r.p.m. full throttle and raced to 3000 r.p.m. The clutch is slipped under these conditions in batches of 10 slips until the total wear of both linings is 0.100", or, if the rate of wear is negligible, until 500 slips are completed. The wear is measured every 10 slips. The attached table shows the results of previous tests on the standard type of clutch with various types of linings, together with results on the new type of clutch. The heat treatment of linings referred to in this table was carried out to remove certain oils left in the linings during manufacture and which caused the clutch to slip when the linings attained a sufficiently high temperature. The chemical treatment is a process carried out by Ferodos for the same purpose. | ||