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 issues caused by axle weakness and a failed attempt to fit a new cross member.
| Identifier | ExFiles\Box 82\2\ scan0167 | |
| Date | 15th August 1934 guessed | |
| - 2 - The 4° traverse axle would overcome the trouble until, as previously stated, modifications are made to the present axle. The following are the reasons why the steering is bad on the Belgian roads, and why, as stated in EP{G. Eric Platford - Chief Quality Engineer}'s. report, the Phantom was not. The trials car in Paris had an axle with the first modification, i.e.- the depressors in the bevel of the neck half filled in.. We were checking up everything that would affect the steering, and whilst doing this I noticed when we were lowering the front of the car off the jack, that as the load of the engine etc. came on to the axle, the overhang from the springs to the hub bent in an alarming way, so much so, that I immediately came to the conclusion that it had cracked. This proved false, however. It was due to the weakness of the neck of the axle. Therefore this weakness, which must be considerably more than is allowed for, alters the traverse lean of the pivot and geometry of the steering, which we assume causes, actually, under the maximum bump, while travelling over rough surfaces, the traverse lean of pivot to be reversed, making the centre line of contact of the road wheels leaning out - wards. A rough measurement taken from the hub caps by a straight edge to the ground, shows the wheels to increase the track by approximately three quarters of an inch, when all the weight is on the axle, as when the load is taken off the wheels. The sketch enclosed shows exactly what occurs. Thus with the 4° traverse lean of pivot, the actual traverse lean becomes under running conditions, that which is designed for the present standard 2° lean axle and accounts for its steadiness. We tried a Phantom under the same conditions and can hardly detect any bending of the axle neck, thus the traverse lean of pivot is not affected. We obtained one of the latest Bentley axles from a chassis at the coach builders and fitted it to the trials car. This axle was approximately 50% stronger in this respect than the one taken off, but is not strong enough to retain the designed traverse lean of pivot, and should be strengthened further.. It is the long overhang that is the chief trouble. After fitting the new axle, I again tried the car over bad pavé, and steering was a considerable improvement, so much so, that no one could object to it. The wing movement is not affected by it. We hope that this is clear, as it solves the peculiar steering that has been complained of. 4 B IV. We attempted to-day to fit the cross member sent out for the above car, but I am sorry to say it is of no use. It has been designed for a car with head lamp pillars on top of the frame. Ours are on the outside, and the centres of the bolts are wider both ways. We could not bring it in either in the centre of the bolt holes or using one pair, as the taper pillar would not allow for the difference in the centres, also the bolts on our car are 5/16 as against 1/4 on the new bracket. We are going to try and get Paris to fit it to the trials car, as that car is a brute for wing movement, and the cross member will fit. The half crankshaft period had developed so | ||