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).
The causes of over-heating in 40/50 HP cars with four-wheel brakes.
| Identifier | ExFiles\Box 24\5\ Scan013 | |
| Date | 27th April 1925 | |
| R.R. 493a (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. X766 REF HS{Lord Ernest Hives - Chair}6/LG27.4.25. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. BJ. c. to E.{Mr Elliott - Chief Engineer} RG.{Mr Rowledge} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to WOr.{Arthur Wormald - General Works Manager} OVER-HEATING ON 40/50 HP. CARS. K9230 X766 We have had complaints of over-heating from Australia on 40/50 cars fitted with four-wheel brakes. We have carried out tests and find that under full throttle conditions there is no reason why the 4-wheel brake cars should be any worse as long as the choke valve in the exhaust pipe is set correctly. Tests on the bench and on the road prove that the heat given to the water is in proportion to the amount the carburetter throttle is open. The heat is at the maximum with the throttle full open. If the throttle is kept full open and the power reduced by baffling the exhaust, the amount of heat units given to the water remains practically constant and does not fall with the drop in power as it would do if the power was reduced by closing the carb. throttle. When the 40/50 with 4-wheel brakes is run full throttle, the choke valve in the exhaust pipe offers no restriction but if the car is run at light throttle, the valve then does offer a restriction, and in order to obtain the same amount of power at the road wheels, the carburetter throttle has to be opened more and more heat is given to the water. contd :- | ||