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).
Report of a visit to Leyland Motors to examine Hall's metal connecting rod bearings and compare different alloys.
Identifier | ExFiles\Box 116\3\ scan0055 | |
Date | 4th December 1937 | |
x 1020 a To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Mths.{Reg Matthews} c. Hs.{Lord Ernest Hives - Chair} REPORT OF VISIT TO LEYLAND MOTORS. This visit was made to Leyland to examine the first set of Hall's metal connecting rod bearings to be supplied to them. These bearings were produced in AC.6 alloy and machined from solid billet. The bearings had completed 75 hours of their endurance which consists of full load running at 1800 r.p.m. the maximum cylinder pressure being approximately 1000 lbs/sq.in. and were in excellent condition. There was no hammering and the surface was very good with the exception of one bearing which had several minute blow holes; in this respect it must be remembered that of the original batch of twelve bearings we turned down six because of bad blow-holes after machining. Only three bearings have been tried at the moment and were run in an engine having three annealed R.R.56 alloy bearings for the other rods. There appeared to be practically no difference in the condition of the two alloys both being really good. The bearings are to be refitted to the engine for further tests in order to compare the tendency to seize and the effect a seized bearing has on the crankpin. At present their experience has been that a bearing seizure when using R.R.56 alloy generally scraps the crankshaft due to cracks forming in the nitrided case. Leylands use a rather deep hardened case allowing for three re-grinds. Our experience has been on our shafts with not so deep a case and using Hall's metal that seizure does not result in a scrapped crankshaft. For their next tests they are fitting the bearings again and are to run with reduced oil supply in order to produce a seizure and note its effect on the crankshaft. We expect that they will seize the R.R.56 bearings first since our own experience has been that R.R.56 has a greater tendency to seize than the AC. alloys with high tin content. We might add that the clearance we specified for their 3.000 dia. crankpins | ||