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).
Manufacturing methods and performance of piston rings for Bentley chassis.
| Identifier | ExFiles\Box 114\3\ scan0195 | |
| Date | 18th March 1937 | |
| Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} C.G.S. C.P.S. BY.7/G.18.3.37. BENTLEY CHASSIS - RE: PISTON RINGS. Referring to Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux}1/R.11.3.37. the position in regard to rings is as follows :- (a). The Aerolite piston is delivered complete with piston rings and gudgeon pins by the Aerolite Co. We donot dismantle the rings from the piston, but apparently from an examination I have had made the rings are heat formed. (b). For replacement work the Works have been despatching the standard 25/30 Hp. chassis piston rings. These are produced by Messrs. Wellworthy, and are produced by both methods, that is to say, we have had them hammered and heat formed, generally speaking they use the hammering or knurling method. In regard to the question of over-oiling, whilst it is evident that a certain batch of rings heat formed have been bad from the point of view of over-oiling, it is certain that this is not due to the heat forming of the ring, as the load exerted by the ring is the same whether heat formed or hammered, and faulty bedding is a question of accuracy of finish of the ring and not a method of obtaining the gap. The Brico Co. who use both schemes have informed us on more than one occasion that heat forming is equally reliable as knurling, and our experiences on experimental work on aero engines confirms this view. In view of your experience I have instructed the Order Office and Repair Department that for Kingsbury until some further instructions are issued they must supply knurled or hammered rings and not heat formed. In the meantime, we will investigate the matter at Derby by running some tests. For this purpose I will arrange to have two sets of rings, one with the knurled or hammered method of stressing the ring, the other set heat formed so that we will be able to confirm or otherwise GWH{George W. Hancock - Head Chateauroux}'s experience, and if we find similar results we will take the matter up with the makers, as it is undoubtedly a question of poor bedding. BY.{R.W. Bailey - Chief Engineer} | ||