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 component failures, analyzing chain breakages, bearing seizures, and an unsound damper design.
| Identifier | ExFiles\Box 124\1\ scan0277 | |
| Date | 30th November 1939 | |
| -3- Rm{William Robotham - Chief Engineer}/JRS.1/JH.30.11.39. A new one was fitted and after a further 2¼ hours this failed in the same way. The cause of this is either misalignment of the bed or due to a low frequency torsional oscillation (see torsiograph report Rm{William Robotham - Chief Engineer}/JRS.12/JH.27.11.39). After 19½ hours running the engine failed and inspection showed that No.2 inlet had broken first at the groove for the spring safety ring. The big end bearings were all in good condition. The chain was cracked in several places and a peculiar point about the breakages is that although the chain is alternat- ively 7 and 8 links wide all the breakages have occurred at the points where the chain is 8 links wide. Also all breaks were on the outside links except in one case where the second link had broken, the first having also broken. From this it seems probable that the failure of the chain is not due to tension in the chain but due to bending across the chain caused probably by misalignment. Before the chain drive is adapted to a car it seems that a positive two way thrust face is essential. Two schemes have been drawn out for thispurpose ECD.1529 and PL.7. The former takes the forward thrust on the wheelcase and for this reason is probably not as good as PL.7 which utilizes both sides of a collar machined on the camshaft as well as being more susceptible to machining and fitting inaccuracies. The seizure of the water pump bearings is due to the non-ventilated type bearings which soon became starved of lubricant and those responsible for this part have recommended that ventilated bearings should be standardised. The failure of the B.60 type damper was not unforseen as the plates are greatly overstressed and the design is unsound. Rm{William Robotham - Chief Engineer}/JRS. | ||