The 147 50 430H is a double acting proportional control and can be used where two side movements should be controlled proportional, like tipper valves, main cylinders of hook or skip loaders.etc.
This multi section air control is designed for applications where several functions should be controlled.
The extra section 14750460H is a double acting NOT proportional control and can be used where two side movements should be controlled black/white.
The extra section 14750450H and 14750455H are single acting NOT proportional controls and can be used where one side movement should be controlled black/white, like PTO, selector valve,etc.