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).
Cancelled travel arrangements, a radiator fan experiment, and a detailed analysis of a Bijur oil pump leak.
| Identifier | ExFiles\Box 5a\2\ 02-page139 | |
| Date | 1st July 1929 | |
| 5810 C To Hs.{Lord Ernest Hives - Chair} From G.W.H. Hôtel de France, Châteauroux, Indre. 1/7/29. The arrangements to meet Mr. Northey in Grenoble have been cancelled, due to Mr. Northey having to be in London on Friday. We are therefore meeting Mr. Northey in Paris, to his arrangements, on Thursday. To the moment of writing, we have not quite completed the 20-HP. The weather having changed and become somewhat warmer, we decided to try the experiment of placing the fan close to the radiator. With this object in view, we have had an adaptor made which has brought the fan to within 1/8" of the matrix at the bottom, we shall carry out a test to-morrow morning to see what difference in temperature we obtain. We received the adaptor for the Bijur oil pump, but as we have had an oil leak down the dash with the oil level approx. the same height as to what the adaptor will give, we lengthened the ferrule of the adaptor making its total length from the underside of the flange to 1.1875". Having had an oil leak with various depths of oil, we determined to go into the cause of the oil leak ourselves and give you our opinion on the cause of the oil leak and the method to cure it. In the first place, the height of the oil in the tank is important, due allowance having to be made for expansion of oil when hot. We have had no time to get exactly what the expansion is, but it is considerable. Secondly once the oil has penetrated through the gauze and by the movement of the car, the whole of the gauze has become covered with oil, the pump rod actually becomes a pump and as the pedal or rod is worked up and down, there being no air inside the filter, oil is naturally drawn up past the rod and into the cavity of the bracket where it is attached to the dashboard. Also there is capillary attraction taking place; this is of course when the tank is full. The leather washer fitted is useless, it does nothing. To defeat the pumping action and the capillary attraction, air must be allowed to go in easily inside the gauze tube. The motion then of any pumping is definitely stopped as there is no compression taking place inside, it being open to atmosphere. To do this we have drilled 6 .125" holes round the flange at the top of the filter. You may say that this spoils the effect of the filter, but we do not think so, as the oil level is considerably below the height of the holes and by the time any splashing takes place, any foreign matter in the oil will have settled to the bottom. Another item which is at fault with the pump is the spring is too large in diameter and when compressed practically becomes choc-a-bloc inside the cylinder. Also another important feature is that the spring is not located at the bottom, and as we found in our case can get to one side with the result that the pressure on the cylinder wall is such that it actually prevented the pump working on one occasion. The spring should be located and slightly less in diameter. [Handwritten on left margin]: Hucks. OK. See report Ho/GR{George Ratcliffe}/14729 | ||