Stick Circuit

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Stick Circuit

The stick circuit consists of the following major components:

-stick 1 spool

-stick 2 spool

-stick cylinder

-stick regeneration valve

-stick unloading valve (part of stick regeneration valve)

-stick lowering control valves (not shown)

-stick drift reduction valve

NOTE: The stick priority systems and the stick drift reduction valve will be discussed in more detail later in this presentation.

Stick 1 Spool: The stick 1 spool controls oil flow from the idler pump. The stick 1 spool receives a STICK IN pilot signal on the bottom of the valve, and a STICK OUTpilot signal on the top of the valve.

Stick 2 Spool: The stick 2 spool controls oil flow from the drive pump. The stick 2 spool receives a STICK IN pilot signal from the joystick on the bottom of the valve stem. The stick 2 spool receives a STICK OUTpilot signal from the joystick on the top of the valve stem.

Stick Cylinder: When oil is supplied to the rod end of the stick cylinder, the stick will retract for a STICK OUT. When oil is supplied to the head end of the stick cylinder, the stick will extend for a STICK IN.

Stick Regeneration Valve: The stick regeneration valve opens during STICK IN to allow returning oil from the rod end of the stick cylinder to be directed to the head end of the stick cylinders during STICK IN. Regeneration is used to reduce "stick wag" and increase the STICK IN speed.

Stick Unloading Valve: The unloading valve allows the oil to return to the tank when regeneration is not necessary.

Stick Drift Reduction Valve: The stick drift reduction valve is placed in the stick circuit between the main control valve and the stick cylinder. The stick drift reduction valve prevents oil from leaking from the rod end of the stick cylinder.

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When the stick hydraulic circuit is operated independently of other hydraulic circuits, stick 1 control valve and stick 2 control valve are operational for both the STICK IN and STICK OUT operation. When the stick 1 control valve and the stick 2 control valve are operated, the supply oil from the idler pump and the drive pump is combined. The supply oil from both pumps flows to the stick cylinder.

The supply oil from the drive pump flows through the parallel feeder passage in the main control valve group to the stick 2 control valve. The supply oil from the idler pump flows through the center bypass passage in the main control valve group to the stick 1 control valve.

When the joystick for the stick is moved to STICK OUT, the pilot oil flows from the pilot control valve to the stick 1 control valve and the stick 2 control valve.

The pilot oil shifts the stick 1 and stick 2 control valve spool. Supply oil is directed from both spools to the stick drift reduction valve. The lock check valve in the drift reduction valve shifts and combined pump oil flows to the rod end of stick to retract the cylinder.

Return oil from the head end of the stick cylinder flows back to the stick 1 and stick 2 control valves and to the tank.