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 Cadillac Motor Car Company regarding steering gear characteristics and comparisons.
| Identifier | ExFiles\Box 170\2\ img287 | |
| Date | 28th June 1935 | |
| CADILLAC MOTOR CAR COMPANY CADILLAC AND LASALLE MOTOR CARS DETROIT, MICHIGAN June 28, 1935. Mr. W. A.{Mr Adams} Robotham, Rolls Royce, Limited, Derby, England. Dear RM{William Robotham - Chief Engineer}: Replying to Mr. Hardy's letter of May 29, I have delayed dealing with this until now because of tests being made here. Have discussed this question with Mr. Denyes of Saginaw Steering Gear Division and we have arrived at the following: (1) The Marles gears are apparently of the double toothed roller type. Does the contact occur on the outside of the teeth, like on ours? This is important because it is the true helix angle between tangent planes at the contact point which determines the reversibility of the gear. In other words, in two gears which are identical except for inside or outside contact, the inside-contact gear is much more reversible. (2) Friction at the contact point is believed to be quite small. It cannot be much without rapid destruction of the contacting surfaces. The greater friction comes from the mounting bearings of the worm, roller, and sector-shaft. (3) Difference in wheel-fight characteristics between gears, we are sure, is largely a question of stiffness between end of pitman arm and steering wheel. In other words if the gear is mounted on a bed plate with the end of the steering-wheel shaft locked solid, and deflection tests taken at the pitman-arm ball ("Pendulum-lever"), the "softer" gear will almost always be found worse for wheel fight than the "stiffer" gear. Stiffness of the mounting brackets and the chassis frame enter into this overall stiffness, of course, in actual use on the car. | ||