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).
Technical memorandum detailing the reasons for changes to the steering components on Wraith and Bentley cars.
| Identifier | ExFiles\Box 153\1\ scan0264 | |
| Date | 18th April 1939 | |
| WRAITH AND BENTLEY STEERING. With reference to Sg.{Arthur F. Sidgreaves - MD}2/E.17.4.39. returned herewith, the information which Sg.{Arthur F. Sidgreaves - MD} asked for is given below:- (a). Change to the lighter article. The change was not made with the object of lightening the piece but to obtain the best compromise between the size of the balls in the races on which the follower roller was mounted and the section of the roller. Whilst the rollers did not fail, the balls in the races on which they were mounted did fail, the balls in question were originally 1/4" in diameter. Because of these failures the series of experiments were put in hand by Ransome & Marles at our request and with the Adamant'Co's co-operation. The size of the balls were increased in stages until we were able to carry a load of 3600 lbs. on the roller when running in a rig at 400 revs. per minute for two hours. A recent example of the failure of the balls is given in complaint budget H.1/C.15.4.39., the car in question being GWN.68, owned by Miss Milnthrop, mileage covered 12,620. (b). The changes in the design were forced upon us by the failures of the balls in the races, they were concurred in as a result of the experiments by our Designers. (c). At the time these changes were made and the steering was introduced, it was not considered that there would be any material difference between the Wraith and the 25/30 it replaces 1 cwt. or so extra in weight would not materially affect this issue. (d). Standardisation sheet Rm.{William Robotham - Chief Engineer}342 was issued and signed up before the change was made on the Bentley car. In the case of the Wraith, the improved steering was a part of the Wraith scheme from the beginning. As a standardisation sheet was issued and signed up this particular point does not arise. (e). What does the customer get out of it ? The change was undertaken to overcome the failures of the balls on which the follower roller was mounted. The change was only undertaken to overcome this defect. The tests which we made at the time the change was made indicated that our object had been achieved, but Hoffmann's failure to control the material and 'treat' the rollers properly landed us in our present difficulties. | ||