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).
Further tests on thermostats for 'M' Series Bentley cars, focusing on valve and bellows combinations to resolve oscillation issues.
| Identifier | ExFiles\Box 156\2\ scan0089 | |
| Date | 16th May 1938 | |
| To Bv. from Rm {William Robotham - Chief Engineer} /Std. c. Hs. {Lord Ernest Hives - Chair} c. RHC. {R. H. Coverley - Production Engineer} c. Roy. {Sir Henry Royce} cc Mx. {John H Maddocks - Chief Proving Officer} THERMOSTATS FOR 'M' SERIES BENTLEY E.B.3509. Further to our Rm {William Robotham - Chief Engineer} /Std.1/MH. {M. Huckerby} 10.5.38, we have carried out further tests with regard to the question of valve and bellows size in connection with the "water hammer" and bellows oscillation mentioned in above memo. As already mentioned we find that the 1 1/8" dia. bellows and 1.2812" dia. valve seat (used instead of the 1 1/2" dia. bellows and 1.156" dia. valve seat instructed for 1st. 100 of 'M' series cars) gives satisfactory results - its movement and operation is very steady, with no hunting or bellows oscillation. We have now tried the standard diameter bellows (1 1/2" dia.) with the larger diameter ((1.156")) valve - the water hammer effect and rapid bellows oscillation is still present. We have also tried the 1 1/8" dia. bellows and the standard valve size (1.156" dia.) and with this combination the water hammer effect disappears, while the bellows oscillation becomes a very slow one. We still consider the small diameter bellows and large diameter valve the most desirable combination since it not only cuts out high frequency oscillation of the bellows, but also very much reduces the bellows working movement - however, in case of a car being fitted with a car heater or any trouble being experienced due to bellows fatigue it would be possible to change the bellows unit only and get rid of any noise from the heater as well as improve matters for the bellows. If possible we still wish to get the complete modification, i.e. small bellows and large valve, on 'M' series cars when it has been run sufficiently, and is convenient, so that machining of the valve seat and bore of the thermostat casings beyond the 100th. chassis should not be completed. Rm {William Robotham - Chief Engineer} /Std. | ||