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).
Comparison of the EAC and 40/50 throttle governors, detailing their respective pull, movement, and performance characteristics.
| Identifier | ExFiles\Box 66a\3\ scan0033 | |
| Date | 1st January 1925 guessed | |
| -3- PARTICULAR. COMPARISON OF EAC. & 40/50 THROTTLE GOVERNOR. EAC. 1000 r.p.m. Governor pull 5.75. 900 r.p.m. Governor pull 4.5. Decrease 1.25 lbs. 40/50. 1000 r.p.m. Governor pull 2.5 900 r.p.m. Governor pull 2 Decrease .5 lbs. This will allow - EAC. throttle to be moved through - .112 X 45 -------- = 12½° on the cam opening the throttle. .4 40/50 HP. throttle governor to move through - .05° or 1/20 of the whole range. ---------- Now for the EAC, 12½° on the cam at a maximum equals. 10° on the throttle, at a min, .3° on the throttle. Therefore the opening of the EAC. throttle for a given r.p.m. drop may be 1/8 or 1/240 of total throttle movement. This may seem an impossible combination of circumstances, but we consider something of the sort might occur on the road as follows :- The hand control might initially be set when descending a gentle gradient where the slightest throttle opening say 2°, would be sufficient to maintain a speed of 30 m.p.h. The cam is now working on the slow portion of its movement. Owing to a change in the nature of the road, the engine r.p.m. drop 100 r.p.m. This, from the above figures, rotates the cam through 12½° contd :- | ||