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).
Engine bearing failure due to zinc-alloy growth and a recommendation for increased clearance.
| Identifier | WestWitteringFiles\U\January1930-April1930\ Scan127 | |
| Date | 26th March 1931 | |
| -2- Hs{Lord Ernest Hives - Chair}/CHP.1/AJ.26.3.31. Contd. speed increased to 2000 R.P.M., upon which the crankcase became exceptionally hot and smoke issued from the breather. After twenty minutes running under these conditions the crank- case cooled to a normal temperature. The engine was just as tight, however, on closing down. The engine was now run for a further six hours at approx. full load at speeds between 2000 and 3000 R.P.M. without any improvement in freedom. Although the engine could barely be moved by hand, the power at 3000 R.P.M. was quite normal. Upon stripping the bearings down it was found that the zinc-alloy had "grown" considerably; the metal having partially filled up the oilways in the bearing cap etc., appearing to have been in a semi-plastic condition. A quantity of small particles of the alloy had been pushed out at the bearing edges. The crankshaft shewed a deep blue temper colour in places, proving a temperature of above 300°C, but was not damaged in any way by abrasion. It is suggested that a set of these bearings should be made, having a very large clearance (say .005" - .006") so as to give the alloy room to grow without tightening on the shaft. When such a set have been run without trouble, the clearance could be reduced on subsequent sets until tightening up is again experienced. Hs{Lord Ernest Hives - Chair}/CHP. | ||