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 cross steering tube load, permanent set, and wear on ball pads.
| Identifier | ExFiles\Box 181\M9\ img086 | |
| Date | 25th November 1931 | |
| To Da.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/AD25.11.31. X.7425. X.5425. You will remember that you wrote asking us whether the variation in cross steering tube load was due to the spring taking a permanent set, or wear on the ball pads. We have carried out a number of tests to answer your queries and were unable to produce wear on the pads on the bumper test nor could we make the springs take a permanent set. It has since been discovered that it is possible to nip the inner contact piece by tightening up the biting in bolts as per attached print until it ceases to move at all under the spring pressure. The clearance at this point between the brass pad and the tube in which it lies is only .001 as the minimum. We find by increasing this clearance to .005" as the minimum we can make sure that the biting in bolt breaks before the brass pad is gripped by distortion of the tube. On the 25 HP. the same results can be achieved by ensuring that there is .003" clearance between the brass pad and the tube. We are not, of course, positive that this is the complete solution to the variations in the cross steering tube poundage which from time to time has been experienced, but since the effectiveness of the spring can be completely negatived on any chassis by tightening up these bolts in a normal manner, we feel that it may be the major cause of the troubles. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||