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).
Examination report on engine component failures, specifically concerning connecting rods, bearings, and the spring drive.
| Identifier | ExFiles\Box 91\3\ scan0208 | |
| Date | 8th October 1935 guessed | |
| ( 3 ) A corner of the scraper ring of N° I A was found broken. There was no sign of damage due to the breakages. All the rings were free in the grooves. The Gudgeon pins were amply lubricated and in a good condition. CONNECTING RODS LOP E 86125 LEC 3860 - 4646. E 86117 Forked Connecting Rod. E 86118 Plain Connecting Rod. EX 19470 Bolt Strengthened Type. E 86122-3 Big End Bearings. W/MT. [Handwritten Note Start] Solid Halls Metal. Ivor Bentley wrong - try on the shaft & the rods [Handwritten Note End] The Bearings of the forked rods failed after 6,800 miles. N° 2 seizing up which caused the metal to run. The temperature of the oil was seen to rise rapidly to 125°C when the failure occurred. The actual failure of this bearing in our opinion, was due to the oil feed hole becoming choked up by the breaking up of the white metal. All the forked rod bearings were in a similar condition. The failure of these bearings is, in our opinion, due to weakness of the shell of the fork rod. This caused the metal to crack and break up. The failure is not due to lack of oil. The oil temperature has been on the high side with hard driving, but a good pressure has been maintained. The fact that the plain rod bearings were in a good condition, which are robust, gives a proof of weakness being the cause. The assumption that the leak of oil from the Oil Heater Matrix being the cause can be dismissed, as the leak was such that it did not effect the oil consumption and was only escaping under full oil pressure. CRANKCASE & BEARINGS. LOP E 87328. The Bearings of the Crank journals were examined. With the exception of N° 2 intermediate bearing which showed a slight fracture on the edge of the centre of the bottom half and signs of the metal having been pushed forward, the remaining bearings were in a very good condition. There was on all the bearings a hammering effect taking place between the shell and the aluminium plate. SPRING DRIVE LOP E 86976 LEC 4475 LARGE SLIPPER FLYWHEEL. Throughout the mileage there was no marked period of crankshaft vibration. We did not examine the condition of the slipper wheel, no tools being available. With regard to the tools, we may mention that the present standard Bentley withdrawing tackle would have fitted, had not the thread on the crankshaft been made right hand instead of our standard practice of left hand. The slipping load was even, poundage 26 at 17.1/2 " radius. | ||