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).
Letter from Maurice Olley discussing steering gear design, efficiency, and road handling characteristics.
| Identifier | ExFiles\Box 170\2\ img074 | |
| Date | 17th September 1932 guessed | |
| - 2 - I want to say, however, that our ideals on steering are different. We, with our rear shackled front springs, need a gear which is fairly irreversible to prevent the wheel swinging around in our face due to geometry errors. If the wheel does not move the car will steer a fairly straight average course even on wavy gravel, but if the wheel moves and the driver tries to move with it, the car drifts all over the road. Thus the Marles, which is more efficient and more reversible gives a car which is harder to drive on gravel. Improved geometry would change this picture. Then also our pivot angles and solid side steering tube, etc., give us a "low speed wobble" at a much higher speed perhaps 55 m.p.h., and there is a continuous blending of low speed wobble into shimmy-tramp which is quite different from the Rolls. So that considerable tightness at center point in the gear is sought as a means of general improvement, without causing the definite 18 m.p.h. wobble which you may get on the Rolls. I do not know whether you will have much luck with this tight spot, unless you use a solid side-tube and a shimmy shackle of about 10,000 #/inch (at the spring eye). You can adjust this tight spot to what you want by means of the eccentric adjustment "A" provided. The Marles gear is now made with roller thrusts and with needle bearings for the roller and rocking shaft. Also with angular ball bearings in the roller etc., and with single and double tooth rollers. I think you would find that we can fill your requirements perfectly with this type of gear, which can reach 75% efficiency and is different from nearly all others by being "sprung" together with absolutely no backlash anywhere. The hourglass worm, though it looks simpler, is, I am sure, not as good in principle, since there must be a backlash at the two main bedding surfaces, which in addition, are too small. However, I would ask you to please try the Cadillac gear even though it may not feel good on the bench, as I think you will find it better on the road than you expect. On our cars it comes back on corners very nicely. Then, if you want to go further, let us send you the best we can do in a late type Marles. As to the controls, light switch (LaSalle type) etc., these were put on "faute de mieux" and you can use them or not as convenient. In any case please let me know what you can find out about it. Kindest regards. Sincerely, Maurice Olley | ||