An intermittent air discharge fluid circuit includes a main valve including a discharge pilot chamber and a pilot valve including an air supply pilot chamber. The main valve is switched between a first position in which the air supply pilot chamber is connected to an air supply source and a discharge port is open to atmosphere, and a second position in which the air supply pilot chamber is open to atmosphere and the discharge port is connected to the air supply source. The pilot valve is switched between a first position in which the discharge pilot chamber is open to atmosphere and a second position in which the discharge pilot chamber is connected to the air supply source.

An assembly for machine leveling including a plurality of hydraulic cylinders having upper ends adapted for supporting the machine's base, a lower end, a shaft, and a port opening the cylinder; branch conduits having cylinder ends and pump ends, each branch conduit connecting to one of the ports; first shutoff valves connected to the branch conduits for alternatively permitting and resisting fluid flow within the branch conduits; a manifold conduit connected to the branch conduits; a hydraulic pump connected to the manifold conduit and adapted for raising hydraulic pressure within the manifold conduit to a shaft extending pressure; and an electrically modulated variable pressure relief valve connected to the manifold conduit and adapted for raising and lowering the hydraulic pressure.

An intermittent air discharge fluid circuit includes a main valve including a discharge pilot chamber and a pilot valve including an air supply pilot chamber. The main valve is switched between a first position in which the air supply pilot chamber is connected to an air supply source and a discharge port is open to atmosphere, and a second position in which the air supply pilot chamber is open to atmosphere and the discharge port is connected to the air supply source. The pilot valve is switched between a first position in which the discharge pilot chamber is open to atmosphere and a second position in which the discharge pilot chamber is connected to the air supply source.