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).
Steering gear difficulties, particularly with the bronze box, and observations on oversteering and understeering.
| Identifier | ExFiles\Box 173\4\ img083 | |
| Date | 19th November 1935 | |
| COPY. (Memo. from Da.{Bernard Day - Chassis Design}) DETROIT. 19. November, 1935. To E.{Mr Elliott - Chief Engineer} from Da.{Bernard Day - Chassis Design} Steering Gear. It is suggested that one of the difficulties in our steering is the bronze box. Here they preload the worm bearings to 100 lbs. The roller is also preloaded in its bearings and the roller pushed with a fair load into the worm thread, so that the whole gear is set up with friction. I do not know how much of this we do. The suggestion is that the expansion of the bronze box causes slack between the roller and the worm, when the gear is heated up, and they claim to have experienced this trouble over here when using a bronze box. There also might be unloading or slack in the worm bearings from the same cause. It sounds as though this might be worth looking into. We have not yet seen the Saginaw people themselves. We have to-day been over to the General Motors Proving Ground, and tried a number of cars for steering characteristics. Olley's contentions as regards oversteering and understeering, recorded in the table we sent you on Saturday, seemed to be generally borne out, but what one thinks of the resulting steering seems another matter. The Chevrolet Master which they describe as a definitely understeering car and objectionably so, I thought was the nicest feeling car of the lot and so did Grylls. A similar car with 15° of "bent-arm Dubonnet" to reduce the understeering, seemed much less safe, and their own Buick fitted up so as to produce a slight understeering effect, even less so still. The understeering on the Chevrolet Master did not, it seemed to me, produce an objectionably strong self-centring effect, but was quite reasonable. Olley says that he would expect the SpectreCodename for Phantom III to oversteer, and says that the Bentley does oversteer. The conclusion we have come to for the moment is that they have not yet appreciated accurate steering, exactly placing the car where it is mounted, and that their conclusions ought to be received with caution. Mr. Taafe of the Proving Ground has suggested that chunking in the drive may be reduced by the friction of | ||