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).
Competitor car features, focusing on brake drum construction and materials.
| Identifier | ExFiles\Box 181\M9\ img064 | |
| Date | 31th October 1931 | |
| -4- circularised scheme of spring controlled weights at the extreme ends of the front bumpers. The new big Hispano Suiza in spite of having three point rubber engine mounting by which frame stiffness is lost does not make any special provision for this trouble. The frame is 7.5" deep at its deepest section and the webs are approximately 2" the thickness of the material being about equal to our P.II frame. The frame does not appear to twain off quite so quickly as ours forward of the dashboard and the front horns are considerably shorter and of less radius. We understand that this car, in spite of stiff road springs, has the defect of considerable wing movement. The radiator mounting was rather hidden but appeared to be centrally mounted and was stayed from the dashboard by diagonal tie rods. This latter feature appears on several cars, Chrysler, Morris, Invicta and others. Brakes. In view of the experiments we are at present making with brake drums having aluminium cooled fins and cast iron liners, special note was made of those in use and the exhibiting brake drum manufacturers were spoken to. The oldest example is that on the Hispano Suiza which has been in use for many years, they use a complete aluminium drum cast round a steel liner, this construction was reported on when we had the Hispano Suiza here at the works in the early days of four wheel brakes. In view of the long time which this method has been in use we attach a sketch showing the construction used. Invicta's use a steel drum having a ribbed aluminium finned cooling flange pressed on and pegged. These were the only two cars found using aluminium in connection with brake drums. Both these methods would appear satisfactory and cheap. With reference to the materials used for the liners the Midland Motor Cylinder Co. Ltd. have produced a cast iron known as Chromidium which they say is eminently suitable for brake drums complete or for brake drum liners, it is used chiefly for dry cylinder liners (centrifugally cast) and diesel engine sleeves. Its advantages are that it retains its hardness in thin sections, is free from hard spots thus making machining easy, is free from porosity whilst its close structure with the chromium content gives excellent wearing qualities. Its physical and chemical properties are as follows :- Total Carbon 3.10% to 3.30% Combined Carbon .60% to .80% | ||