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).
Comparative tests on a standard leather cone clutch and a cone clutch with cotton belting.
| Identifier | ExFiles\Box 74\2\ scan0114 | |
| Date | 1st April 1912 | |
| Derby. 1st April.1912 Mr Royce. Re Cotton Belting Clutches. Mr Platford has made comparative tests with a standard leather clutch and a cone clutch with cotton belting. The test was carried out on chassis 1926 with the same amount of oil in the clutch in each case. The following are the results :- Leather cone clutch. | Load in lbs on the lever | equivalent gradient for chassis weighing 5,500 lbs. | Temperature of clutch surface | Remarks. | |---|---|---|---| | 185 | 1 in 7.92 | - | Clutch started rear wheels satisfactorily. | | 231 | 1 in 6.35 | 115°F.{Mr Friese} | ditto. | | 280 | 1 in 5 | - | Clutch slipped considerably before fully engaging and pedal rose to floorboards. | | 298 | 1 in 4.9 | 170°F | Clutch wearing rapidly but just starts road wheels. | | 310 | 1 in 4.7 | 210°F.{Mr Friese} | Dynamometer weights were lifted by clutch but wheels could not be started. Clutch slipped badly and burnt out completely. | The temperature at the start of the tests was about 100° F.{Mr Friese} On dismantling after the test a large amount of the leather was found to be broken away and the remainder was badly charred and quite brittle. The clutch would not disengage properly nor could the car be driven with any degree of satisfaction. | ||