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).
Analysis of cooler failures due to soldering and distortion, with proposed corrective actions by a supplier.
| Identifier | ExFiles\Box 131\1\ scan0243 | |
| Date | 20th November 1936 guessed | |
| -2- (2) These are attributed respectively to - (a) Faulty soldering - we have no evidence to show that weakness of the top plate has caused any pressure leaks, since the failures are not confined to the top edge, but seem to be distrib-uted between top and bottom edges and ends of tubes in the block itself. (b) Distortion of seating faces either during pressure test ( in spite of the clamping plate) or distort-ion of faces during machining (we noticed on one or two coolers that on inspecting them immediately after machining, the faces were out of straight by .002 - .003 th. - this can only be attributed to deflection of the top plate of the cooler while machining and subsequent springing back - itseems likely that unless great care is taken, burning of the plate may occur when the unions are brazed to it, with consequent thinning of the metal around the union and increased flexibility here- this had actually taken place to such extent on one of the coolers which the writer saw tested by your Mr.Meats that leakage occurred through the plate itself, see attached marked-up drawing. (c) Faulty soldering - since only a small percentage of coolers haved failed in this manner - in the case of these few the margin of safety has been insufficient in spite of the stipulated pressure test - we have yet to experience a failure in service of a cooler which has passed our pressure test. (3) The steps which are to be taken (by Messrs John Marstons Ltd.) to improve matters (1) a.{Mr Adams} and c. are as follows - (i) Adopt chemical and individual cleaning (prior to dipping) of each component part of the cooler. (ii) Adopt dipping of the complete cooler in a jig instead of hand soldering the case to the block as at present. To obviate item (1) b., the following will be done - (i) Arrangements will be made by us for Messrs. John Marston to build the cooler into its aluminium case and test the matrix for oil leaks as at present and the union joints for water leaks - we shall finally pressure test the matrix here in its case as a unit before fitting same to car. continued | ||