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).
Design and operation of a throttle governor, comparing the EAC and 40/50 chassis.
| Identifier | Morton\M3.2\ img007 | |
| Date | 1st January 1925 | |
| TO HS.{Lord Ernest Hives - Chair} FROM E.{Mr Elliott - Chief Engineer} S E C R E T EL/M12. 1. 25. Copy to CJ. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. re. THROTTLE GOVERNOR. X8140 In considering the governor question on the EAC. and 40/50 chassis, the biggest and most important difference is that the 40/50 has a balanced piston throttle requiring very little power to operate it, and the EAC. has a balanced butterfly throttle, but which carries an unbalanced load amounting to about 35 lbs. at low speeds due to induction pipe depression, and requiring sufficient operational effort to overcome the bearing friction caused thereby. It is needless here to state the advantages attached to using the butterfly throttle on EAC. In consequence of the above Mr. Royce firstly decided that the work required from the governor should be reduced to a minimum, and queried the Exp. Dept. as to what maximum throttle opening was required. The control was arranged to conform to the figure supplied. Secondly Mr. Royce saw that owing to the fact that the governor power falls rapidly with decreasing speed, whereas on the contrary the throttle friction increases with small throttle openings, a direct coupled governor would be subjected to considerable frictional effects at low speeds, and its behaviour would be most erratic. He therefore conceived the idea of a variable leverage between the two elements which would overcome this disadvantage. Moreover the throttle opening per 100 revolutions obtained with this variable leverage is in accordance with the requirements of the engine, being more in the nature of a constant proportion of the total opening rather than a fixed amount. In this it agrees with the slotted throttle on the 40/50 which provides a considerable step down for low speed governing. It would appear that you require a larger max: throttle opening than originally specified and possibly a spring of lower rating. We expect the governor to give a consistent low speed control running light so that there is no danger of stopping the engine, and also to control the speed of the engine within reasonable limits when the clutch is taken out for changing down on the gears. E.{Mr Elliott - Chief Engineer} | ||