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).
Cutaway diagram and operational description of the S.U. Hydraulic Fuel Pump.
| Identifier | ExFiles\Box 124\5\ scan0015 | |
| Date | 31th December 1931 guessed | |
| INLET PORT OUTLET PORT PETROL INLET The S. U. Hydraulic Fuel Pump provides one of the cheapest and most adaptable means of transferring petrol from petrol tank at the rear to the carburetter. It consists of a small reciprocating plunger pump driven by a hydraulic reciprocating motor. The latter derives its motive power from the oil circulated in the lubricating system of the engine, and thus at the same time the pump provides a positive safeguard against damage being done by a failure of the oil supply. The pump is inserted in the system in such a way that the whole of the oil supply passes through it before going to the bearings. The motor piston consists of a sleeve with a large aperture in the middle. This is normally closed by a valve which is connected to the petrol piston by a piston rod passing through a guide which separates the two cylinders. Both the pistons are supported by coil springs, that under the petrol piston being considerably the stronger. Oil enters above the oil piston and forces it downwards, carrying with it the valve and petrol piston. During this stroke petrol is transferred from below to above the petrol piston by way of a ball valve located at the side of the petrol cylinder. Near the bottom of the stroke the sleeve is arrested by a washer located near the bottom of the oil cylinder, and the valve is forced onwards by the oil away from its seating in the sleeve. The pressure either side of the sleeve is now equalised, and its spring, therefore, throws it upwards and the valve follows it together with the petrol piston which now expels petrol from the top union, and sucks a further supply in through the side union, via the petrol filter and through the ball valve located below the petrol piston. The upward movement of the petrol piston and oil valve is controlled by the demand for petrol. When this reaches the top, the valve seats on the sleeve and the cycle repeats itself. | ||