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).
Radiator cooling capacity, fan belt slip, and engine boiling issues when climbing hills.
| Identifier | WestWitteringFiles\L\July1924-September1924\ Scan24 | |
| Date | 11th September 1924 | |
| R.R. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} -3- EXPERIMENTAL REPORT. Expl. No. REF Hs{Lord Ernest Hives - Chair}/ACL/LG11.9.24. at 22°C for all tests. It was found that a slipping fan belt greatly impaired the cooling capacity of the radiator. Slip is not likely to occur below 1750 r.p.m. with a reasonably tight belt. Factors which will prevent or reduce the tendency to boil on hills. If a car boils when all out on top gear at a certain speed no advantage from the point of view of cooling can be obtained by changing to a lower gear if the engine is still driven at full throttle. From deductions we have made it should, however be possible to climb most reasonable gradients without boiling by changing to a lower gear and at the same time reducing the throttle opening and consequently the road speed of the car. Some curves are given to make clear this point. We assume the car in question to weigh 2 tons. and the curve showing the H.P. required is calculated for a gradient of 1 in 12 from figures obtained for the tractive resistance of a 40/50 H.P. car. Referring to the curve we see that for this particular gradient (1 in 12) we should be able to obtain a speed of approx. 36 m.p.h. at full throttle. This requires approx. 49 H.P. at the rear wheels. We also see from curve No. that the heat given out by the engine at full load, to the jacket water is in excess of that that can be dissipated by the radiator at the corresponding speed and normal temperature conditions. Therefore if the hill were sufficiently long contd :- | ||