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).
Semi-automatic transmission developed by the Eclipse Company, detailing its performance and design.
| Identifier | ExFiles\Box 173\3\ img007 | |
| Date | 10th March 1934 | |
| HS.{Lord Ernest Hives - Chair} -page 3- March 10, 1934 AUTOMATIC TRANSMISSION The Eclipse Company have developed a semi-automatic transmission which appears to me to be more practical than most. It is easier to describe its performance on the road than the exact means by which this is accomplished. There is a small plunger on the column which operates reverse and neutral, otherwise there are no controls. Starting the car from rest it will be found in bottom gear, the clutch is conventional and operated in the ordinary manner. Up to 5 M.P.H. bottom gear remains engaged. After that a change can be made at any time by releasing the torque slightly by easing the foot from the accelerator pedal. There is no shock or appreciable lag. The same means is used to get into top gear. It is the same sort of change as on the Maybach but there is no shock and no lag. Changing down from top to second can be completely automatic. In this case it is a function of torque and speed. The automatic can be set to change into second at any given road speed at a maximum torque. Then, whenever a hill is being climbed which requires full throttle, a change will automatically take place when the car speed falls to the pre-determined value which for America is between 25 and 30 M.P.H. If another hill can be climbed at half throttle, the automatic change will not occur until a lower speed, probably 15 M.P.H. At any time the automatic change can be short-circuited by fully depressing the accelerator pedal hard when second speed will be engaged if within the range of engine speed. It is possible to creep along in top gear provided not much torque is required. Internally the box is of conventional design except for: 1. Centrifugally-operated multiplate clutch. 2. Two free wheel clutches. 3. Two small cam rings. The gears, of course, are constant mesh helical. The advantages of the gear as I see it are: 1. Does away with side levers giving entrance on the driving side of the car. 2. Requires no pre-selection or hand control for normal driving. 3. Throws little strain on the clutch or transmission as changes are made without shock. | ||