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 condition of a crankshaft and low inertia spring drive assembly after testing.
| Identifier | ExFiles\Box 5a\2\ 02-page386 | |
| Date | 30th January 1931 guessed | |
| -5- larger dia. crankpins, placing greater stress upon the bearings. The gudgeon pins and bushes were in good condition and did not show lack of lubrication. CRANKSHAFT to Log 2756/7. E.55619 Crankshaft with 2" dia. crankpins, crankshaft to suit Low Inertia Spring Drive. The condition of the crankshaft journals was not very good. The two ends and the centre had worn unevenly due to the out-of-balance effect. The measurements taken of wear was, No.1 journal .0027" on the dia. on one side of the pin only. No.4 journal .0027" on the dia. on one side of the pin only. No.7 journal .0027" on the dia. on one side of the pin only. The intermediate journals did not show the effect of wear so pronounced. The journals of the connecting rods although of a dark colour did not show any appreciable wear. The amount of sludge collected in the inner bores of the connecting rod journals was considerably less than previous tests, but it was of a very gummy graphite nature. LOW INERTIA SPRING DRIVE to LOP E.54745. scheme 1334. (1) Using double driving springs and stronger damper springs viz- E.56167 Outer driving springs. E.56200 Inner " E.56208 Damper springs. (2) Spring Plate machined with windows to Drg. Ex. 5127 (3) Damping friction 8 lbs. at 17 1/2" rad. To obtain this 4 damping springs E.56208 were removed. (4) Driving spring Load = 9 1/4 lbs at 17 1/2" rad. The Low Inertia spring drive has given entire satisfaction. The engine has been free from any thuds, crankshaft periods or timing gear rattles. The friction load has remained almost consistent. It was at the finish of the mileage 8 1/4 lbs. as against 8 lbs. at the start. The condition of the unit when dismantled was very good. There was no deterioration of any parts. The driving and friction springs had not taken any permanent set. There was no sign of fidgeting of the drive on the taper of the crankshaft. Cotton Duck washers were in a good condition. | ||