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).
The failures of a Bentley Saloon and a 5-B-IV chassis, focusing on crankshaft bearing issues due to lubrication problems.
| Identifier | ExFiles\Box 82\3\ scan0375 | |
| Date | 7th June 1935 | |
| -3- Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}9/KW. 7.6.35. Briefly, therefore, we are still up against the problem that the standardised Bentley Saloon is sold as a complete car but, in spite of our efforts to improve it, the coachwork is not yet sufficiently relaiable. We recommend that when this Park Ward Paris Trials car returns for attention from the Coachbuilders, we should try and rectify the faults in a permanent manner since, the duty being paid, this car will return to run on French roads and so supply us with the necessary information as to the success or otherwise of the modifications. (3) 5-B-IV CHASSIS. As frequently happens, we think we have learned a good deal more from the failures on this car than we usually do on a successful run. Crankshaft & Bearings. An examination of the crankshaft and bearings on this car showed that the failure of the big ends has been mainly due to insufficient lubrication. The position on this car appeared to be that whilst the main bearings were in good condition, sufficient oil got to the big ends to prevent trouble. As the main bearings started to crack up, however, the oil feed to the big ends was reduced until finally failure occurred. The bearings furthest away from the oil feeds failed first, and in one case - No.1 big end which had received the best oil supply - the bearing was in excellent condition. This car has of course been running at oil temperatures up to 120oC., which accounts for the failure of the white metal main bearings. We are satisfied that if we run the main bearings with high lead content lead bronze and white metal clearances, put a continuous oil groove feed in all main bearings, and two holes instead of one in the journals of the crankshaft, the trouble we have experienced can be eliminated. The alternative seems to be to fit an oil cooler. It seems that if the large bore engine is going to require a new crankcase, provision should be made for incorporating the Buick type of oil cooler therin, so that this could be used should it be found essential. | ||