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).
Road test findings regarding damper knocks and a boiling A.C. petrol pump.
| Identifier | ExFiles\Box 11\3\ 03-page383 | |
| Date | 2nd July 1931 | |
| To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} From GWH.{George W. Hancock - Head Chateauroux} Hotel de France. Chateauroux, Indre, France. 87941 2.7.31. 25-EX. We have tried out the car under all conditions that would produce damper knocks. At the present mileage there is no sign of any knocks in either rear dampers. We found that he spring loaded connecting links had not the same poundage, the N.S. being the weakest? This caused a slight knocking on the lever that could be felt but not heard. Taking the friction load of the connecting links with a ten inch lever, we found the loads to be 6.75 lbs on the O.S. and 4 lbs on the N.S. The present arrangement of these new spring loaded links is not fool proof; various loads can be obtained by the screwing up of the bottom pads. There should be a collar to screw up to, so that a given load would be applied. We set ours by screwing them up choc-a-bloc, then unscrewing two complete turns which gives a friction load on the contacts of 67.5 inch lbs. Re. the A.C. Petrol Pump. We are still experiencing boiling trouble with the pump arrangement. We have led the feed pipe along the channel frame then up to the pump at right angles. We do not experience any trouble with this arrangement whilst the car is in motion as the flow of the petrol is sufficiently cool to keep it from evaporating, but after driving approx. 80 MPH. and coming to rest momentary, no petrol will come through for a few seconds, meanwhile the car splutters along, once the petrol is drawn through the pump, it is O.K. The symptoms are, the pump getting too hot evaporates the petrol inside which opens the valve, this can be heard pulsating. We believe it is the valve under the air bottle. It destroys the vacuum and prevents the pump from functioning. We have cured it each time by unscrewing the air bottle and allowing the gas to escape. We should have thought that the position of the pump was in the coolest place. We do not get the fault stated above without driving at 70 to 80 MPH, maximum heat generated. A squeak has also developed in the pump which we have not as yet located. We found the connecting links and lever inclined to be rusty by condensation and have drilled a small hole in the bottom case (SS{S. Smith}6502) to allow the fumes an outlet passage. We believe it is one of the valve mechanisms that is the cause. The present mileage of the car to date is 893. GWH.{George W. Hancock - Head Chateauroux} G.W. Hancock. | ||