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).
Test results of three steering cams produced by the Fellows Gear Shaper Company.
| Identifier | ExFiles\Box 153\1\ scan0105 | |
| Date | 29th November 1937 | |
| To RHC.{R. H. Coverley - Production Engineer} from RM{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to Hs.{Lord Ernest Hives - Chair} c. to Hy.{Tom Haldenby - Plant Engineer} c. to MJJ. STEERING CAMS PRODUCED BY FELLOWS GEAR SHAPER COMPANY. The three steering cams produced by the above Company and which were handed to the Experimental Dept. for test showed the following characteristics on the Production Dept. measuring rig. (1) 25/30.Cam. This had eccentricity errors which made it unsuitable for use in a steering gear. (2) Ph.III.Cam produced with 16 tooth cutter. This cam was satisfactory from the point of view of eccentricity and gave a tight spot of long duration and a relatively small amount of backlash on the locks. (3) Ph.III.Cam produced with 17 tooth cutter. This cam was also concentric and had a tight spot of shorter duration with slightly more backlash on the locks than present standard cams. Of these cams Nos.2 and 3 were the only ones which would be tested and the only difference between them was in the duration of the tight spot and the backlash on the locks. No.2. was bound to be satisfactory in these respects as it was better than present standard. No.3. was fitted to 37-BX. for test. In service this cam was satisfactory, from the point of view of backlash, the increase over standard being not noticeable. It did, however, have a rough and lumpy feel due to roughness of the cam track surface. Our conclusions are that cams produced with either the 16 or 17 tooth cutters would be satisfactory in service if the surface finish was improved. The 16 tooth cam is technically the better one, but, we should have thought, would be more difficult to produce consistently. Apparently, the Fellows Company do not agree, but we think this should be confirmed. In connection with the manufacture of cams in these Works, we wish to point out that the Ph.III. cam will be changed when Wraith wheel movement is introduced. In addition, we believe that the Ph.III. type of adjustment is still covered by patents. We therefore suggest that we should not buy equipment for the existing Ph.III. cam but should begin with the Wraith cam. The cams for Wraith, M.Series Bentley and Bentley III. will be identical. RM{William Robotham - Chief Engineer}/FJH{Fred J. Hardy - Chief Dev. Engineer}1 | ||