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).
Article detailing a new method for the construction of composite steel brake drums, reprinted from 'The Light Car and Cyclecar' magazine.
| Identifier | ExFiles\Box 120\3\ scan0044 | |
| Date | 20th January 1933 | |
| Reprinted from “The Light Car and Cyclecar,” January 20, 1933. COMPOSITE STEEL BRAKE DRUMS New Method of Construction ALTHOUGH brake design has improved appreciably in recent years, there is still room for much progress. Recently we described the Girling brake system which has been developed by Messrs. Pratt and Manley, of Guildhall Buildings, Navigation Street, Birmingham. These two engineers, acting in conjunction with Messrs. Holden and Hunt, of Old Hill, Staffs, have now evolved a new brake drum of considerable merit. The new drum can be made in any material which is weldable. Normally a 0.4 per cent. carbon steel is used; thus the wearing quality of the rubbing surface is excellent. A suitable rolled section of this material is bent into a circle and the joint is electrically welded. Constructional Details. Into one side of this “rim” a steel disc is spigoted and the two parts are pegged and welded together to form the complete drum. The disc is, of course, adapted to suit the wheel hub and the rubbing surface of the drum is ground out to ensure that it shall be concentric and even. Several advantages are apparent in this construction. A hard-wearing material can be used without interposing a joint through which all heat must flow. Furthermore, the material has a strength and reliability which is not possessed by cast-iron. Consequently, the new drum is lighter than a cast-iron drum of equivalent section. Comparing it with a pressed-steel unit, there is an advantage in compactness and in rigidity. This last feature is due both to the compact layout and to the fact that the drum can be ribbed and can be thicker than is convenient for a pressing. With the last-named method of manufacture the drum must be wider for a given shoe width, because an appreciable radius is essential in the corner where the “rim” joins the disc and also where the other edge of the rim is turned outwards to form a lip. Finally, there is a point which will appeal strongly to many car owners: The new drum does not squeak. This appears to be due to the fact that the welding between the disc and the rim is not continuous. Also the two parts are of different steels. Consequently, any vibration which tends to occur in one is immediately damped out by the other. Theory apart, however, the fact is that when one of these drums is struck with a hammer it emits only a dull thud. Most ordinary drums, on the other hand, make excellent gongs! Price is always an important matter and in that connection Messrs. Pratt and Manley state that this brake drum compares favourably with other high-class drums. Already several car manufacturers have shown much interest in the development and, like the Girling system of brake operation, it is likely to be seen on various models in the near future. PROVISIONALLY PROTECTED. Temple Press Ltd., 5-15, Rosebery Avenue, E.C.1. Image Captions: PEGGED & WELDED JOINT The drum in section, showing how the rim is fitted to a disc adapted to suit the wheel hub. A pressed steel drum (dotted lines) compared with the new built-up drum to show the saving in width. | ||