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).
Butterfly throttle load issues at low speeds and potential solutions involving control levers.
| Identifier | ExFiles\Box 66a\3\ scan0057 | |
| Date | 21th April 1925 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG21.4.25. butterfly throttle at low speeds due to unbalanced suction. An additional cause of load on the hand control was found to be the throttle closing spring. To ensure that the butterfly throttle has the same force tending to close it as the 20 HP., a torque of about 4 ins.lbs. is necessary on the throttle spindle. When the throttle is opened to the full 40°, the camshaft torque necessary to rotate the spindle increases from 0 to 11.5 ins. lbs. (see attached print) due to the rating of the throttle closing spring being necessarily appreciable and the leverage from the cam rapidly decreasing. The attached scheme demonstrates the difficulties. The load occasioned on the hand control by this unavoidable feature of the butterfly throttle, is appreciable. The only way in which we can reduce the load on the hand control without reducing the governor sensitiveness is to alter the lengths of the levers on either side of the control spring. Attached is a sketch of two sets of levers which shew the method employed. We believe, however, that we can satisfy Sales without altering the lengths of these levers as originally specified, though the operating manual effort will be over 100% greater than that required on the 40/50. We have had considerable difficulty in eliminating the cause of complaint (a). We first attacked the unlubricated cam, as we considered that the load imposed upon it by the throttle closing spring was sufficient to set up friction. This was replaced by W.W. with a roller and arm, but though this was an improvement, there was still contd :- | ||