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).
Disappointing foundry conditions, material test results, and arrangements for sample castings for the Bentley III.
| Identifier | ExFiles\Box 142\4\ scan0083 | |
| Date | 13th August 1937 | |
| - 2 - HPS.{Horace Percy Smith - Experimental Factory Mgr}4/VS.{J. Vickers}13.8.37. The Foundry itself was very disappointing, the work being carried out under terrible conditions. Furthermore, they have no means of checking up castings, there are no facilities for heat treatment, all of which has to be done outside, and they have no pyrometer for the furnace and all casting temperatures are left for the furnace man to estimate. Castings are made in green sand, using wood patterns, the castings being knocked from the mould within a few minutes of pouring, this being necessary to avoid cracking, which is liable to take place during the period of cooling in the case of castings which vary appreciably in sectional thickness. We were informed that the maximum tensile strength of their material in the cast condition should be in the region of 27-30 tons/sq.in., and they have since forwarded test bars at our request in order that we might obtain further information as to its physical properties, since they have no one, except apparently Mr. Gabriel himself, with any technical knowledge, and unfortunately he was not available at the time of our visit. The figures obtained from the mechanical tests carried out are as follows :- Maximum Stress. 26.2 tons/sq.in. Yield Point. 13.2 tons/sq.in. Elongation. 13.5% Red. of Area. 20.8% Brinell. 117. After discussing various discrepancies on the sample castings supplied, Messrs. Gabriel were asked to produce three sets of upper and lower triangle levers for Bentley III. Proof castings of the upper triangle levers are now in our possession and the lower triangle levers are expected today. Whilst we have not yet received any castings from Messrs. W. Jessop Ltd., Sheffield, they have the advantage of a competent technical staff, long experience in the production of high quality steel castings and good foundry methods and equipment. Unfortunately, however, the work we have to offer is of a much smaller nature than that to which they are accustomed, and they are not, therefore, equipped to produce such castings on an economical basis. Furthermore, they are already working to capacity, and whilst they are willing to co-operate with us in continued. | ||