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).
Sticking points and potential solutions for the Spectre Marles steering system.
| Identifier | ExFiles\Box 28\3\ Scan156 | |
| Date | 10th May 1935 | |
| 4300 To E.{Mr Elliott - Chief Engineer} from Da.{Bernard Day - Chassis Design} c. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} SECRET. Da.{Bernard Day - Chassis Design}6/HP.10.5.35. SpectreCodename for Phantom III - Marles Steering. The sticking points on the first SpectreCodename for Phantom III Marles steering seem likely to prove to be due to the worm being out of centre, so causing tightness on one full lock and extreme play on the other; and to the fact that the point in the central position where there should be no slack cannot be the actual tightest point, as, fitting as we do on the outside of the roller teeth there will obviously be two still tighter points as each of the two roller teeth pass over the centre. This feature was masked a little by the worm itself being out of centre. It has to be cured by allowing a slight slack in the central position. According to Commander Maltravers, this slack is scarcely perceptible, but he thinks the two tight places on either side the centre should still be just appreciable. Whatever this slack is, it could be reduced by approximately 2/3 by fitting on the inside of the roller teeth. According to Commander Maltravers the American makers have gone from one side to the other several times and have now finished on the inside. The only disadvantage seems to be that the shocks in the central position exert an increased pressure on the roller teeth due to the angle of pressure of the teeth, which reaches a maximum as the tooth face passes the centre. Commander Maltravers is positive that grinding is unnecessary and practically impossible. It is not done by anyone, but the Americans cut their worms by a species of hobbing process in a Fellowes machine. The axis of revolution of the hob is at right angles (or nearly so) to the worm. We have investigated the probabilities of grinding with a wheel revolving in the same direction as the roller, and as far as we can set it out it appears to be possible, provided the wheel is not much larger than the | ||