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 endurance testing, detailing component failures and subsequent modifications.
| Identifier | ExFiles\Box 124\1\ scan0276 | |
| Date | 30th November 1939 | |
| -2- Rm{William Robotham - Chief Engineer}/JRS.1/JH.30.11.39. the half and quarter load hours were run as follows - 15 mins. at 3000 r.p.m. 15 mins. at 3500 r.p.m. 30 mins. at 4000 r.p.m. After two hours endurance the water pump seized. This was fitted with a non ventilated bearing. After 4 hours endurance the dynamo adjusting strap failed and after 5 hours the crankshaft damper which was of the B.60 type also failed. A similar damper was fitted and after 8½ hours endurance the front wheelcase was dismantled to find that this damper had also failed and that the camshaft drive chain had cracked in 16 places. At this point it was decided to limit the maximum speed to 4000 r.p.m. and the speeds of 4250 and 4500 r.p.m. were replaced by 1000 and 2000 r.p.m. to give some running at high M.E.P's. A heavy type chain and a Studebaker type damper were fitted but after only one further hour a bad front end rattle had developed. Up to this time the camshaft had only a thrust face to take thrust to the rear but with the chain drive there is no thrust from the drive and the only thrust occurring is from the distributor and oil pump gear and the direction is forward. Consequently the alignment of the chain, when running is bad as the amount of end float of the camshaft is considerable. In view of this it was decided to refit a light chain, and at the same time to limit the camshaft end float to .002 - .003 by providing a forward thrust face. This was accomplished by fitting the wheelcase with a ball end tappet adjusting screw bearing against the camshaft plunger. Before recommencing the endurance a power curve was carried out and during the warming up for this curve the water pump again seized. The power curve is shown on the attached sheet and also the exhaust back pressures. Endurance was recommenced without trouble until after 14½ hours the clutch centre plate sheared. | ||