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).
The 'Last' infinitely variable speed mechanism, detailing its operation, improvements, and disadvantages.
| Identifier | ExFiles\Box 156\4\ scan0071 | |
| Date | 4th August 1937 | |
| 1330 By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} Hs.{Lord Ernest Hives - Chair} Da.{Bernard Day - Chassis Design} Hdy.{William Hardy} Cx.{Major Len W. Cox - Advertising Manager} Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}5/R.4.8.37. "LAST" INFINITELY VARIABLE SPEED MECHANISM. Mr. Last visited us just before the holidays to discuss his transmission. He was not able to demonstrate its behaviour on a car as the only one of such a size ever made and fitted to an Austin had not been repaired since failure, some years ago. The most obvious improvement in this transmission over others of a similar type such as the "Spontan" is that a free wheel is not essential. The torque to drive the propeller shaft is derived from the reaction of a spinning member that varies its moment of inertia, due to masses following a cam on this driven member. The engine rotates the part having variable inertia. It is claimed that full torque in direct drive can be used down to any desired speed, and, at the same time, the indirect or variable speed mechanism can stay in operation up to max. speed. This requires mathematical investigation as we doubt under these circumstances whether the weight of the mechanism would be practicable. One disadvantage that came to light was that at zero, or a very low speed, full throttle would result in the engine running up to the valve bounce or other limiting factor as the change speed mechanism exerts little or no restraint. As far as the driver is concerned, the operation could be described as having a gearbox with a direct drive or indirect drive. If in direct drive the indirect is obtained by closing the throttle and suddenly opening it after which the "gear ratio" will depend on the throttle opening; the more throttle the lower the gear. To change back into direct the throttle is closed and then gently opened. | ||