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).
Investigation into recurring failures of the 20 HP side steering tube, analyzing material properties and proposing solutions.
| Identifier | ExFiles\Box 56\4\ Scan020 | |
| Date | 16th November 1926 | |
| X5450 U.W. H.{Arthur M. Hanbury - Head Complaints} B.I. Wof. Hs.{Lord Ernest Hives - Chair} ---- BY12/H.{Arthur M. Hanbury - Head Complaints} 16.11.26. NC F&S [STAMP: RECEIVED 18 NOV 1926] 20 HP. SIDE STEERING TUBE. --------------------------- During the last month we have had three instances where the side steering tube has broken on the 20 HP. chassis, at the bend. We are sending you the broken tube taken from Chassis 71-A-8. This was delivered in 1923, and has done approximately 25,000 miles. Special attention was given early on to the question of the shape of the tube where the bend was produced, to ensure a circular section being maintained. We also put up the Brinell at the same time. In testing out the broken tube I find that the Brinell is up to our limit, and that the fracture can not be ascribed to faulty material. The tube is heat-treated in the first place before being hand brazed. We do not dip braze this piece owing to the liability of the dip brazing plant to lower the Brinell figure, and from an actual test we find that the Brinells we have quoted in the first place are maintained on the tube. In view of the whole facts of the case, it certainly does appear that we are working near the margin on the 20 HP. side steering tube, possibly due to the fact that the 20 HP. has always suffered from wheel joggle to a large extent, which would in itself result in high alternating stresses being thrown on the side steering tube. It certainly appears to me to be necessary, in view of the whole facts of the case, for us to face a programme which will deal with the whole of the cars delivered, particularly as we ought also to consider the side steering tubes on all 20 HP. chassis from the point of view of overcoming joggling on thewheel by the introduction of lighter springs with more possible movement in the side steering tube itself, so that since we will unquestionably have to deal with the latter in a great many cases, we could combine the two points and make a virtue of necessity in this case to improve the steering Contd. | ||