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).
Tests conducted on the Phantom II throttle spring.
| Identifier | ExFiles\Box 13\4\ 04-page149 | |
| Date | 29th April 1933 guessed | |
| -1- TESTS ON PHANTOM II THROTTLE SPRING. These tests were carried out on Ph.II. No.25. (large bore engine), fitted with large air valve S.S. carburetter. The throttle body of this carburetter was fitted with phophor bronze bushes, as used on production, and the throttle spring arrangement was fitted up as scheme LeC.3412. As requested in this scheme, a 7/8" radius lever was substituted for the 1" radius one shown on drawing. Tests. The engine was run with the throttle practically closed - idling speed. Induction Pipe Depression, 17.5" Hg. Length of spring in this position was measured and corresponding load determined by stretching spring to this length with a spring balance. The load (applied to throttle control arm) necessary just to move throttle was measured by means of a spring balance and effective radius of application of load measured (10 readings of this load were taken and the mean value is given below). The spring load with the throttle fully open was also measured as a check on the accuracy of the lever mechanism and found to be correct, 9 lbs. Results:- At 7/8" Rad. - Spring length, throttle closed, 2 3/4". load 3 lbs. 9 ozs. Load just to move throttle against spring and bearings 3.4 lbs. (mean of 10 readings) Radius of application of last load, 1.7/16" Torques:- Spring torque, 3 lbs 9 ozs x 7/8 = 3.12 lbs.ins. Torque to move throttle against spring section and friction - 3.4 x 1.7/16" = 4.88 lbs.ins. ∴ Frictional torque = 4.88 - 3.12 = 1.76 lbs.ins. ∴∴ Excess of spring torque over frictional torque = 77.3% of frictional torque. | ||