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).
Test results and recommendations for preventing crankcase fumes in the 40/50 chassis.
| Identifier | ExFiles\Box 74\3\ scan0128 | |
| Date | 19th July 1921 | |
| S.H. 235A (100 T) (S.H. 798, 10-12-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2947 X3908 To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to Rg.{Mr Rowledge} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} Hsl/LG19.7.21. X.3908 - CRANKCHAMBER VENT IN 40/50 CHASSIS. We strongly recommend that if we are going to the expense of fitting a special breather in order to prevent the fumes from the crankcase getting inside the body, we should do something to prevent the crankcase fumes coming out of the crankcase at the point where the three oil pipes are fitted to the main bearings. The vent area round these pipes is very considerable. If we fit a new breather without doing anything to prevent the fumes coming out at the three main bearing oil connections, we shall have only tackled half the job. We suggest that the most practicable way of dealing with existing cars might be to fit a felt washer, but on future engines we build a scheme might be got out so that there is an oil trap to prevent the fumes coming out at that point We have carried out a number of tests on a 40/50 engine on the Test Bench measuring the pressure in the crankcase by means of a water gauge. We find that the pressure in the crank-chamber of a present standard engine when running full power is only .050" to .125". If we stop up the breather entirely, the pressure rises to .250". If we stop up the vent round the oil pipes as well as the breather, the pressure rises to .375". We found that with the crankcase in this condition that we could reduce the pressure to normal if we had a .375" dia. vent pipe. We recommend, however, that we should not use anything less than contd:- | ||