| 摘要 |
A pump piston in one cylinder is connected with a power piston operated by compressed air in a second cylinder rigid with the first, and a common rod connecting the pistons extends from the second cylinder so an adjusting screw abutting its end serves to give fine adjustments to the stroke to give accurate measurement of the amount of slurry dispensed in each operation. The slurry is delivered by gravity to the pump cylinder, and air operated valves control the communication between the pump cylinder and the gravity supply conduit and also between said cylinder and a discharge nozzle, where an air operated plunger clears the nozzle of slurry at the end of each discharge. A servo valve cooperates with two trip valves to control the air flow for operating the power piston, as well as the air-operated valves and nozzle plunger, one trip valve being operated automatically at the end of the forward stroke of the pistons to start the return stroke and the other being either operated automatically by a can moving into filling position or at the end of the return stroke of the pistons. The servo valve is of novel plastic construction, as are also the two trip valves. In the servo valve, the reciprocable slide valve is of a plastic material having appreciable lubricity in relation to the plastic material of the seat for easy operation and long wear, while in the trip valves both the body part with the valve projection on it and the fulcrummed arm that carries a valve seat gasket are of extremely hard rigid plastic material to avoid any flexing of the arm in the opening of the trip valve against the resistance of its return band, close accuracy of movement of this arm both ways being important for close accuracy of measurement of the material dispensed.
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