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).
Letter to Ransome & Marles Bearing Co. Ltd. regarding the heat treatment of follower rollers for the 25/30 HP chassis steering gear.
Identifier | ExFiles\Box 153\2\ scan0172 | |
Date | 9th November 1936 | |
1300 c.c. RM{William Robotham - Chief Engineer}/Mr. Hardy. 9th. November 1936. 27H EY.S/C. Messrs. Ransome & Marles Bearing Co. Ltd., Newark on Trent. Dear Sirs, 25/30 HP. CHASSIS - STEERING GEAR. FOLLOWER ROLLERS. Our Mr. Hardy has been discussing with me the points that were talked over during his visit to your Works on Saturday last. The principal point which I think he is raising is the question of tempering by stress releasing treatment for the follower roller after hardening, apparently there are two variations you would like to make from the instructions we have passed along, the variations in question being :- (a). Instead of using oil as the medium for stress releasing you prefer to use your equipment for a similar process which is already installed, consisting of an electrically heated muffle in which a fan is installed to circulate the air with pyrometers suitably disposed to ensure a regular temperature throughout the whole of the muffle. We have no objection to this system being used, in fact we use it ourselves on the heat treatment of aluminium castings, taking, of course, care to see that there are ample air spaces between the various parts being treated. (b). The length of time of treatment, in our experience which is mainly associated with gear tooth grinding, we have found that it is essential to give two hours in order to completely eliminate cracking. We understand you consider 20 minutes will be sufficient. We appreciate the fact that the cracking is a function of the amount of grinding which is done, and the length of the line in contact between the part and the grinding wheel, and we would be quite prepared to test on our magnetic crack detector pieces which have been treated by your scheme for 20 minutes, and can immediately satisfy ourselves as to the efficacy of the treatment or not. | ||