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 design and challenges of a steering mechanism for a tank power plant.
| Identifier | ExFiles\Box 144\4\ scan0190 | |
| Date | 10th December 1940 guessed | |
| 8. about because the steering mechanism has to be so geared as to maintain manouverability on difficult ground at low speeds and consequently is too high geared for the maximum turn that can be used at high speeds. This increase of power loss in the steering clutch is more than in direct proportion to the speed increase. For our projected tank power plant, we appear to have the choice of retaining the Wilson steering units as on the existing Marks V and VI or of designing the simplest possible layout of the controlled epicyclic system. We have rejected the two Wilson units on the grounds of weight, cost and loss of performance. There is a further objection to the Wilson units, the importance of which we have not yet assessed. The absorption of power for steering purposes occurs on one of the brake bands in each Wilson unit and the heat generated appears as general gearbox temperature. Trouble is already being experienced on Mark V, and presumably also Mark VI, with excessive gear- box temperatures. Owing to the higher speed of our project, this trouble is bound to be more acute. We have adopted a controlled epicyclic system incorporating a two direction steering clutch running at 2500 r.p.m. which stands some chance of dissipating its heat. The attached print Rm.{William Robotham - Chief Engineer}663 shows the layout. As we have synchromesh in the main gearbox, it is essential to keep to a minimum the inertia of the parts to be synchronised. This rules out the Merritt Brown design as the steering brakes, gears and differential on this are connected to the input shaft of the gearbox. To get over this difficulty, we have taken our supplementary drive from the engine side of the main clutch by V belts. This drive will also be very useful for auxiliaries. The normal maximum H.P. of this drive will be about 70. The use of belts has the advantage of protecting the drive against an otherwise possible overload of 200 H.P. due to inertia effects when accelerating the engine with the main transmission in neutral. Our use of a steering clutch running at high speed has introduced a difficulty which is as follows. The steering mechanism is arranged so -Continued- | ||