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).
Inspection report detailing failures of engine components including cylinders, pistons, and connecting rods after dismantling.
| Identifier | ExFiles\Box 5a\2\ 02-page385 | |
| Date | 30th January 1931 guessed | |
| -4- We found upon dismantling the cylinders that No.4 bore had become badly scored down one side owing to the failure of the piston gudgeon pin locking ring. The cylinder is having to be scrapped as the damage is too great to be rectified. The remaining bores are in a very good condition as regards wear and lubrication. PISTONS to LOP E.55804, E.55576, PISTONS, E.5586/2 PISTON RINGS Although we have not heard any piston knocks and have had no sign of overoiling, the pistons when taken out for examination were found to be in a poor condition. No.4 had become badly scored through the gudgeon pin locking ring having become loose and fidgeted about until a groove had been made in the side of the piston 1.125” long, .6125” wide and .1875” deep. The piano wire locking ring along with the piston metal displaced had wrought havoc with the cylinder wall as previously stated. There were two more locking rings on the verge of coming adrift. It would appear that there is not sufficient metal left at the end of the gudgeon pin bore to support the locking ring, the recess being too near the outer edge, also the recessing of four holes to manipulate the locking ring takes away valuable support. The locking rings definitely fidget sideways, presumably by the end movement of the gudgeon pins. This is to be immediately rectified by deleting three of the recessed holes, one has been found ample to manipulate the locking ring, also the recess for the ring to be moved inwards .025” leaving more metal for support. No.6 piston was found with a section of the skirt broken away. The section ran parallel with the vertical slot up to the horizontal slot 1.250 wide. It gave the impression that there had been too much pressure on the piston which would come about through a partially seized gudgeon pin. The fracture shows definite signs of fatigue. The above effects must have occurred at approx. 8,000 miles as we spent some considerable time trying to locate a blow, which was located at No.4 cylinder. It was thought at the time to be due to seized piston rings, but during the following day’s run it had almost disappeared. We therefore left it until the final examination. We have not had any signs of the piston overoiling and when dismantled there was ample lubrication. The carbon deposit was heavier than usual for the mileage. CONNECTING RODS to LSC 2786/7 E.55808/9 Con. Rods & Caps E.55613 Bushed (whitemetal) to suit crankshaft with 2" dia. crankpins. The connecting rod bearings were of a dark colour and the bearing surfaces were full of cracks. There were no score marks and very little wear had taken place. The probable cause of the cracks is the higher engine speed combined with the | ||