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).
Analysis of gear backlash in a steering assembly, with recommendations for bearing improvements.
| Identifier | ExFiles\Box 106\3\ scan0394 | |
| Date | 10th August 1936 guessed | |
| -2- A possible reason why gears develop backlash after some running is that, as assembled, the outer races of the cam and rockershaft bearing may not be abutting correctly on their packing washers. This is possible as the fit of the races is sufficiently tight to maintain them in position particularly in the case of the rockershaft bearings, where the load is mainly radial. To investigate this point we tried on four 20/30 steerings, giving the lower end of the pendulum lever a sharp blow in either direction, and an endwise blow on the outer end of the rockershaft. Table No. 2 shows the effect of this upon the preloading. In all cases the preloading was reduced. We recommend that similar steps should be taken during assembly to ensure that the bearing races are hard against their washers. HS{Lord Ernest Hives - Chair}/CWL. reports that during its running in France, the Steering of 22-6-V developed 0.050 backlash on the pendulum lever end, but at the same time there was still 1 1/2 lbs. preload on the gear. Owing to the presence of backlash this preload must have been on the cam bearings and its amount is very little less than the 1 1/2 lbs. which the cam was originally assembled. This suggests that the backlash was due either to wear on the roller follower bearings or on the rockershaft bearings. Wear between the teeth of the cam and the roller is always very small. Wear on the roller follower bearings will undoubtedly be reduced by correctly made bearings with the reduced track radius. In the case of the rockershaft we suggest that the present steep angle roller bearings are not the best type for the application as a small amount of wear will allow the rockershaft to move away from the cam appreciably. The Timken bearings asked for by production to simplify grinding should also be of assistance in reducing backlash as the angle of the bearing is more acute so that the position of the rockershaft would be less sensitive to wear. Hs.{Lord Ernest Hives - Chair}/F.J.Hardy. | ||