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).
Clutch slipping issues on high compression 25 HP cars due to increased torque.
| Identifier | ExFiles\Box 5a\5\ 05-page104 | |
| Date | 8th February 1930 | |
| To Ba. From Ha/AJL. c. to BY.{R.W. Bailey - Chief Engineer} X5771 He/AJL.1/W.8.2.30. X.5300 X.5770 X.5771 CLUTCH SPRINGS ON HIGH COMPRESSION 25 HP.CAR. We are experiencing considerable trouble with clutches slipping on the 5.25:1 compression 25 HP. cars. Trouble is also experienced but to a lesser degree on the standard 25 HP. car. On looking into the matter we find we are still using the same clutch and clutch springs as were used on the original 20 HP. engine. The torque increase is considerable over the original 20 HP. and it is necessary to strengthen up the clutch springs to obtain the same freedom from slipping. When changing over from small bore to 3.25" bore the torque increase was at its maximum at 750 R.P.M. and was in the region of 28%. The second change to 5.25:1 compression ratio has given us a maximum increase in torque at 1000 R.P.M. of 35.2% over the original 20 HP. engine. We have had to increase our clutch spring load as a temporary measure by packing up the existing springs on the two high compression 25 HP. cars. The job is rather urgent as a high compression car is leaving for 10,000 miles test in about a week and should be fitted with modified clutch springs. Ha/AJL. | ||