Engineering journal page detailing the Ljungström single-lever control system for motor-cars with component illustrations.
| Identifier | ExFiles\Box 156\4\ scan0022 | |
| Date | 18th November 1927 | |
| 660 ENGINEERING. [Nov. 18, 1927. LJUNGSTRÖM SINGLE-LEVER CONTROL FOR MOTOR-CARS. CONSTRUCTED BY MESSRS. AKTIEBOLAGET SPONTAN, STOCKHOLM, SWEDEN. FIG. 7.—CRANKSHAFT AND ROTARY UNIT. FIG. 10. CRANKSHAFT AND ENGINE FLYWHEEL. FIG. 8. ROLLER CAGES AND OPERATING MECHANISM. FIG. 11. WEIGHTS AND ECCENTRICS. FIG. 9. CENTRAL SHAFT, ROLLER CAGE AND GROOVED SLEEVE. FIG. 12. PENDULUM WHEEL. between the rollers and the inclined surfaces on the sleeve forms a brake, or sprag, which automatically prevents the car from running backwards. Without this device described, it might be impossible, on account of the weight of the car, to change the gear into the reverse position if it were desired to do so. There are a number of further interesting features of the gear which will be brought out by a study of the design. Referring to Fig. 13, which shows the two weights and their associated parts, the conditions corresponding to the car being at rest with the engine running may first be considered. Under these circumstances, the outer sleeve of the clutch will be stationary, and the flywheel will be revolving. It will not affect the principle of the gear if it be assumed that this motion is uniform. The turning moment on the sleeve will then be given by the radius OO’ multiplied by the component of the centrifugal force, due to both weights, at right angles to the line OO’. If C is the centrifugal force due to each weight, the turning moment is evidently OO’ x 2 C sin α. Since the radius R is constant, and we have assumed uniform rotation, C must be constant, and the torque can be represented by a simple sine curve, as shown in Fig. 14. The actual values for the torque given in this figure are based on the proportions of the gear as fitted to the 11-h.p. Fiat car already referred to. The variations in the positive torque are, to a great extent, taken up by the flywheel attached to the driven shaft in the gear box, so that the actual torque on the propeller shaft follows the slightly-undulating curve shown in the upper half of Fig. 15. Such small angular fluctuations as occur in this flywheel are still further eliminated by the elasticity of the propeller shaft itself, so that the torque on the back-axle is practically uniform. The negative component of the torque is taken up by the pendulum wheel attached to the stationary sleeve, which, as explained, is coupled to the casing of the box through a number of springs, which are radial when the wheel is at rest. Here, again, the torque actually transmitted to the casing is practically uniform, as shown in the lower half of Fig. 15, because the small angular movements of the pendulum wheel only produce a slight difference in the stresses on the springs. One of the objects of the pendulum wheel, that of freeing the reversing mechanism, has already been explained, but it should be pointed out that the presence of this wheel, and its flexible attachment to the gear-box casing, results in the angular oscillations in the negative torque being confined to the elements within the box, instead of being transmitted to the car frame and setting up vibrations in the latter. Space does not permit of our entering into the theoretical considerations involved when both the flywheel and sleeve are revolving, but a curve showing the actual variation in torque when the propeller shaft is running at half the speed of the motor is given in Fig. 16. It will be observed that there are two periods in each revolution in which no torque is being transmitted to the propeller-shaft flywheel, and these correspond to the absorption of power to overcome the inertia of the stationary parts, and the giving out of this power | ||
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).