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).
Description of the principal parts and function of the Spontan transmission system, including a diagram.
| Identifier | ExFiles\Box 41\4\ Scan038 | |
| Date | 21th September 1931 guessed | |
| SPONTAN PRINCIPAL PARTS AND THEIR FUNCTION The valuable properties of the Spontan transmission system are based upon the principle of maximum flexibility in the connection between engine and propeller shaft. This flexibility is obtained by the action of rotary bob weights, the centrifugal forces of which are used for transmitting the drive from the engine to the propeller shaft. This explains the fact that at low engine speed with correspondingly small centrifugal forces the engine is, in effect, free from the drive and that even at the highest speeds ample flexibility remains to enable instantaneous and smooth speed adjustments to take place between engine and propeller shaft. The main working parts of the Spontan gear are shown diagramatically in Fig. 1. Referring to this figure, assume that the two bob weights attached to cranks on the propeller shaft, are carried round by being connected, through pivoted links, to the flywheel of the engine. If the resistance of the shaft is sufficiently small, the centrifugal force of the weights will be able to keep the propeller shaft turning at the speed of the engine which, thus, is driving the car "on direct drive". Should the resistance of the propeller shaft increase, e.{Mr Elliott - Chief Engineer} g.{Mr Griffiths - Chief Accountant / Mr Gnapp} due to the car climbing a hill or being accelerated, the centrifugal force will be insufficient to turn the shaft at the engine speed and the bob weights, still being carried round at the speed of the engine, will start revolving on the crank pins. It will be seen that the centrifugal force then no longer tends to turn the propeller shaft in the same direction all the time but gives it a series of turning impulses in alternate directions, the turning moment changing direction for every 6 SPONTAN half revolution of the bob weights on the crank pins. By means of two roller clutches introduced between the cranks and the propeller shaft, as shown in Fig. 1, the impulses acting in one direction are separated from those acting in the [Diagram Labels for Fig. 1] Pendulum Wheel Reaction Clutch Rollers Driving Clutch Rollers Engine Flywheel Bob Weight Propeller Shaft Flywheel and Brake Drum Engine Crankshaft Propeller Shaft Crank Pins Driven Sleeve on Propeller Shaft Main Driving Sleeve Reaction Sleeve Spring Fig. 1. other direction, the former being utilized for driving the propeller shaft and the latter being flexibly absorbed by the car frame. In the actual design the two cranks are replaced by eccentric discs on which the bob weights can revolve by means of ball bearings. The principle of the roller clutches is shown in Fig. 2. 1 is the main driving sleeve receiving oscillatory turning impulses from the rotating bob weights mentioned above. The inner sleeve, 2, is the driven sleeve on the propeller shaft and the outer one, 3, is the "reaction" sleeve, flexibly anchored to the gear casing as shown in Fig. 1. The annular space between each two sleeves contains a set of rollers, the work- 7 | ||