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).
Test report on an improved Claudel-Hobson air-driven petrol pump, analyzing its performance and suggesting modifications.
| Identifier | ExFiles\Box 61\3\ scan0329 | |
| Date | 1st April 1932 | |
| V4038b. Pg. From Hs{Lord Ernest Hives - Chair}/Aln. c. to Mr. Ey. c. to Lr.{Mr Ellor} c. to Mr. Jaques. HS{Lord Ernest Hives - Chair}/Aln.1/MA.1. 4. 32. CLAUDEL-HOBSON AIR DRIVEN PETROL PUMP. We have now tested the improved form of this apparatus originally reported in Hs{Lord Ernest Hives - Chair}/Aln.a/KT.30.10.31. This design is very similar to the first model but the pump pistons are fitted with cup leathers while the regulating valve or control diaphragm is smaller and lighter than the earlier example. Attached is a curve showing air consumption against petrol delivery working with a 40 lbs. per sq.in. air supply. As before, the consumption is nearly in direct proportion to the delivery up to high deliveries of about 500 pints per hour, above which the air consumption increases at a faster rate. The ratio however, is smaller than before, the volume ratio of petrol flow to free air used being about 1:1.72 which is equivalent to working at 25.3 lbs per sq.in. abs., (10.6 lbs gauge) without cut-off. Or, air consumption is about 60% of what it was on the old pump. There is now practically no leakage of air into the petrol, but there would seem to be still some direct escape of air each time the trip valve on the pump operates to reverse the stroke. The working pressure permitted by the regulating valve is normally about 3.0 lbs. per sq.in. The pressure regulation however, is the one rather poor feature in the functioning of the apparatus. For small petrol flows, it is kept very steady, but at deliveries above about 150 pts per hour, at each reversal of the pump a pressure of 15 or more lbs. per. sq.in., is produced for a short time which, of course, a carburetter needle valve cannot hold. The fault appears to lie with the pump rather than with the regulating valve, as the excess pressures do not occur when the valve operates during the completion of a stroke of the pump, but they always occur (when the condition holds) at each reversal of stroke. A momentary collapse of the petrol pressure probably allows the regulating valve to admit too large a gust of air. We improved matters a little by fitting an air bottle on the petrol line. Elasticity in the petrol line may not be so disadvantageous as previously suggested as it may act as a reservoir to even out the pressures on the regulating valve. A fairly large bottle with an easy entry and exit placed near the pump, might considerably improve the action. | ||