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).
Endurance test report for a Borg & Beck clutch fitted to a Buick car.
| Identifier | ExFiles\Box 129\2\ scan0026 | |
| Date | 5th March 1935 | |
| TO Hs.{Lord Ernest Hives - Chair} +2200 Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux}7/KW.5.3.35. Endurance Test of Borg & Beck Clutch. We have carried out an endurance test with the Buick Car fitted with a Borg & Beck Clutch. The test has been as follows. The car started off from stationary in direct drive. Engine revs. - approximately 1500 to 2000. Clutch engaged normally and full throttle used as the drive was being taken up. A speed of 30 m.p.h. was reached before allowing the car to slow up on its own deceleration. Car finally braked and test repeated. The engagement of the clutch was very smooth at the beginning of the test, with no sign of jaggers under any condition, and no sign of slipping. After 326 engagements the clutch started to slip. This was found to be due to the wear of the fabrics allowing the clutch fingers to foul the clutch casing, preventing the load of the springs to be in operation. The clutch was dismantled to ascertain its condition. The fabrics were in a perfect condition and had only worn approx. .010" off the thickness. The case being a pressing and no man labour spent on it, no provision had been taken to allow for inaccuracies in the pressing when the fingers operated. It was obvious that insufficient clearance had been allowed, therefore we cleared away the case to leave sufficient clearance for adequate wear of the fabrics. The clutch was re-erected with the increased clearance for the fingers. The clutch engagement was still smooth and free from any sign of jaggers. A further 1140 engagements, making a total of 1440, were made before it again started to slip. The engagement up to this had been smooth and free from grabbing. The slipping was due to wear of the fabrics, the clearance for the operating fingers having been taken up. This is the limit of wear allowed as we are now down to the rivets. Also, the clutch pedal had started to rattle, through the limit of travel having been reached, leaving no spring tension to hold the pedal in position. The clutch springs have taken a set of .1875" during the tests. Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} | ||