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).
Comparison of Merlin and Bentley engine lubrication systems and bearing specifications.
| Identifier | ExFiles\Box 141\2\ scan0225 | |
| Date | 22th July 1940 | |
| Cont'd.{John DeLooze - Company Secretary} - 3 Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}I/ML.22.7.40. Total bearing perimeter. Discharge from oil pump under load. Maximum pressure due to gas and inertia. B/AC Main oil pressure. Merlin 189.3" pts/hr 3800 @ r.p.m. 2,600 lbs/ins. 1,530 @ r.p.m. 2,600 131 70 lb/in. Bentley 131.9" 3,400 @ 4,000 1,450 @ 4,000 178 30 lb/in. The above Bentley figures refer not to the centre main bearing but to the outer intermediates which are the heaviest loaded and those most subject to failure. They are also worked out for the speeds at which the respective engines runs the major portion of their type tests. From these figures the factor for Bentley is 36% better than that for Merlin. Even supposing the factor to be quite fair this does not provide a complete answer to the problem, since an aero engine does not have to cater for the high torque low speed condition which occurs with a motor car and for which the lubrication system has to be designed. Nevertheless the Bentley system is successful and it does not really matter for what original reason the system was so designed. Figures for main oil pressure are given in the end column. These should not have a direct effect upon the lubrication. Provided the oil has once reached the bearing, the pressure in and distribution of the oil film is no longer a function of the pressure at which it is introduced. 12% of the 202 engines (Merlin II. III. IV. X) returned for service during March, April and May, had big end trouble, 4 1/2% having partial failures and 7 1/2% having complete failures. - Continued - | ||