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).
Stop and restart tests, a non-return valve, and the advantages of an evaporatively cooled system for armoured cars.
| Identifier | ExFiles\Box 182\M21\ img085 | |
| Date | 9th May 1933 guessed | |
| -5- These tests included a stop and restart test on a gradient of 1 in 5. This was carried out easily and 15 mph. was quickly reached in 1st gear at a point where the gradient was 1 in 5.4 General Remarks. Non-return Valve. This is used to prevent the radiator tube block filling with water whenever the engine is stationary or ticking over below 600 RPM. The valve is of the hinged disc type see R.R.Sch.375. The disc is vertical and is kept on its seat partly by water pressure and partly by its weight, the hinge being offset. Since the valve was new and the seatings were in a good condition, no leakage was measured through the valve, but if after long periods of service the seating corrodes and leaks, the condenser would fill up with water when the car was left stationary. On starting up, however, the head of water in the condenser would cause it to flow through the injector venturi into the pump inlet until the header tank becoming partially filled, the pump would develop enough pressure to work the injector. The chief disadvantage of a leaky S.R. valve is that water might be lost through radiator leaks when the car was left standing for long periods. It is not certain what working margin the injector capacity provides over the condensate for high power outputs, but if after some time, scale in the piping reduces its efficiency by a noticeable amount, the fitting of slightly larger piping and a larger injector would cure the trouble without necessitating a larger water pump. A strainer of some kind should be introduced into the system to eliminate the possibility of foreign bodies blocking the injector nozzle. Appendix. Advantages of an Evaporatively Cooled System for Armoured Cars. (1) Normal water-cooled systems suffer from severe water loss whenever boiling takes place in hot countries. Evap. systems work at a higher temperature but only lose small quantities of water in the form of steam. (2) Small radiator leaks are comparatively unimportant, large radiator punctures which might be experienced in action would not empty the water system, and the car would probably be able to carry on as long as necessary. (3) Very quick warming up. (4) When once warmed up the system will keep hot for long periods even in cold weather. Ha/T.D. de Paravicini. | ||