Tank spreader

A liquid manure spreader comprising:

• a tank having a chamber for storing liquid manure, means having an opening in communication with the chamber, a cover closing said opening, pump means for selectively evacuating air from the chamber and supplying air under pressure to the chamber, control valve means for selectively controlling the movement of air to and from the chamber, air line means connected to the cover and valve means providing an air connection between the valve means and the chamber, manure discharge means on the tak for spreading manure when air under pressure is applied to the chamber, manure inlet means allowing manure to move into the chamber when air is evacuated from the chamber, safety shut-off valve means located inside the chamber operable to prevent the evacuation of air from the tank through the air line means in response to the level of the manure in the chamber, said shut-off valve means including valving means movable to a closed position in response to the level of the manure in the chamber to prevent escape of liquid manure into the air line means and pump means, and means attaching the shut-off valve means to the cover, said control valve means including a housing having a bore, a first section and a second section, said bore extended through said sections, a first port in the first section open to the bore and to the atmosphere, a second port in the first section open to a bore and to the air intake of the pump, a third port in the first section open to the bore and air line means, a fourth port in the second section open to the bore and atmosphere, a fifth port in the second section open to the bore and air exhaust of the pump, a sixth port in the second section open to the bore and air line means, a spool rotatably located in said bore, said spool having a first cavity and a second cavity, said first cavity positionable in a first position in communication with the first and second ports and a second position in communication with the second and third ports, said second cavity positionable in communication with the fifth and sixth ports when the spool is in the first position whereby air under pressure is directed from the pump to the air line means, and positionable in communication with the fourth and fifth ports when the spool is in the second position whereby air is evacuated from the air line means by a pump.