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).
Replacement and material specifications for faulty steering rollers in Wraith and Bentley models.
| Identifier | ExFiles\Box 153\1\ scan0272 | |
| Date | 19th April 1939 | |
| 13 50 RHO. Sg.{Arthur F. Sidgreaves - MD} Hy.{Tom Haldenby - Plant Engineer} G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Rm.{William Robotham - Chief Engineer} BY.2/G.19.4.39. F.J.H. WRAITH AND BENTLEY STEERING. RE: RHC.{R. H. Coverley - Production Engineer}1/FH.14.4.39. As the result of instructions issued to replace the rollers which are likely to be faulty, we have a steady supply of 10 rollers a day promised. The first 10 were received yesterday, and we have Messrs. Hoffmann's promise that they will keep the necessary machines on our work to maintain this. In future, we will produce the rollers up to the hardened and stress released condition, the rollers will then be sent to Messrs. Hoffmann's for finish grinding. We have told Messrs. Hoffmann that they must replace all faulty rollers at their cost. We have a total of 700 rollers on order, which will well cover our present building requirements and replacements, with enough rollers over to enable us at the end of this week to arrange to replace rollers on all cars delivered; in the interim no chassis have been delivered to coachbuilders or finished cars to owners without fitting, tested, satisfactory rollers. Turning now to the question of material, I will confine myself to actual facts. The material is that used for Phantom III change speed gears, it was also used for the first hundred of the new first motion shafts for Wraith. We have used this material for reduction gears on all our aero engines, as well as many smaller parts on the same service. In no case have we experienced any difficulty in regard to the heat treatment of the parts in question. The Section of the gear teeth in the chassis boxes made in this material have less thickness than the roller under discussion. The Adamant Co, who are the licencees for this steering gear use similar material, and all steering gears on American cars are made in it, and we know of no other material which will replace it satisfactorily. We know that Nickel casehardening steel has not a sufficiently stiff core. The rollers received from Hoffmanns which have been produced in material supplied by us have under test stood three times the maximum working load of 35 foot lbs. necessary to turn the road wheels from lock to lock (full) without failure. At 3½ times the full load the roller failed, but at the same time the balls were forced into the surface of the race. | ||