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 different tank steering systems, including Plain Differential, Clutch & Brake, and Double Gearbox.
| Identifier | ExFiles\Box 144\4\ scan0187 | |
| Date | 10th December 1940 guessed | |
| 5. 1. Plain Differential. In order to steer the tank, the brake on the inner track is applied to produce the desired resistance to motion on this track. This brake has to absorb half the engine output plus the work done by the inner track which objects to being slowed down. As mentioned earlier, this work done by the inner track varies from half to three times the engine output at high speeds. This system is the simplest but is also the most wasteful of power. It obviously greatly reduces performance, as the tank lives on its inertia when turning at high speeds. 2. Clutch & Brake. This is a modification of the first system in that the inner track is disconnected from the drive on turns and its brake has only to absorb the work done by the track. This can be called a 25% improvement on system 1, but still kills performance on a curved road and on large high speed tanks results in very serious heat dissipation problems with the brakes. 3. Double Gearbox. With this arrangement the gearbox driving the inner track is changed to its lower ratio. In the case of Marks V and VI this lower ratio is 0.875 of the normal straight ahead ratio and results in a fixed turning radius of 90 feet. If a more gradual turn than this is required, as will be the case under most conditions at speeds exceeding 25 m.p.h., the brake band controlling this ratio in the Wilson box is not fully engaged but used as a slipping clutch control. If a turn sharper than 90 feet radius is required, the steering box concerned is put into neutral and the tank is steered on the clutch and brake system. This system is probably a 50% improvement over the plain differential from the point of view of wastage of power. Both the Wilson gearboxes have to be capable of transmitting full 1st. speed torque and are too large for manual operation. 4. Renault Geared Differential. This gives a result similar to the double -Continued- | ||