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).
Laboratory examination report on the construction and finish of a Lincoln chassis brake drum.
| Identifier | ExFiles\Box 120\1\ scan0209 | |
| Date | 3rd September 1937 | |
| Handwritten: A.F.R. How do they get such high total carbon free from blow holes & porosity M 400 Rm{William Robotham - Chief Engineer} File 1028 Typed: Mr. Knaggs from Foundry. c. to SY. c. to RMC. c. to Rm{William Robotham - Chief Engineer} c. to Mr/Er. Martindale. c. to H.P.S. H1/FJW.1/JN.3.9.37. Laboratory LINCOLN CHASSIS BRAKE DRUM. The cast iron rim of this drum is anchored to the .126" thick pressed steel centre by a series of ¼" holes, ½" apart, close to the outer edge of the steel. The iron fills these holes and covers the edge to a depth of about ⅛". The thickness of the cast iron at this point is about 9/16". A section of the drum has been prepared in which part of the cast iron has been cut away to expose the edge of the plate and demonstrate its construction. This section is shown in photograph No.3062 C. The fracture of the iron is grey except in the ¼" holes on the side nearest the centre of the steel plate and in the edge of the overlapping cast iron. As requested we have examined the section for the presence of tin which you suggested might have been used to prevent the iron "kicking" off the chill surface, but both microscopic and chemical tests gave negative results. It is evident that the edges of the steel plate cannot have been tinned, as we find that the part covered by the cast iron is blackened with oxide and scale to an extent for which the heat of casting would not account. The holes in the edge of the plate are punched out, as evidenced by the markings inside them, and the slight bulge in the edge of the plate opposite each hole - see photograph. After casting, the whole part has been sand or shot blasted. That this was not done prior to casting was shown by stripping the oxidised edge by pickling. The steel beneath the scale showed no sign of sand blasting. -1- | ||