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).
Production methods and materials for a new flexible gear design.
| Identifier | ExFiles\Box 15\6\ Scan111 | |
| Date | 27th May 1930 guessed | |
| 4. 6. Production. The design is flexible, and lends itself admirably to mass production methods. The basic items such as the cam, follower, and half ball elements are already being produced most economically, and with very simple plant. Again, owing to its extreme compactness in relation to its load capacity, the material charges on this gear are considerably less than those of similar types. It will, for instance, steer a 30 cwt. touring car without undue unit pressure on the contacting surfaces, owing to their dimensions, and unique characteristics. Under this item there are other points of interest and importance. The half ball elements are surface ground to shape from Hoffmann steel balls in a very simple fixture; the large quantity handled at one setting resulting in an extremely low unit labour charge. The follower is made from annealed high tensile steel. The cup-like recesses are roughly prepared with the point of a drill, and the half ball elements then simply "Brinelled" into position by means of a press; the necessary overall width across the faces being determined by master spacers slightly less in width than the cam track, to allow for the elasticity of the metal, and necessary clearance. The follower is finally heat-treated and ground on diameter. (See detail drawing and sketch). The cam track is a simple thread of square section, roughed out ready for grinding on an Automatic screw cutting machine, hardened, and finally ground on the flanks on a simple fixture, employing a master nut, and using a 4" dia. wheel set over to the necessary angle, and suitably trimmed. The all important assembly and labour charges are kept very low, as relative positioning of the cam, rocker shaft, and follower are not at all critical, owing to the self-aligning characteristics of the half ball elements. These are held in position by oil suction alone; in practice a quite satisfactory arrangement. | ||