Fast STICKIN - Regeneration

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Fast STICKIN - Regeneration

For a fast STICKIN, or whenever the return oil pressure from the rod end is higher than the supply pressure to the head end, the check valve will unseat.

When the check valve unseats, the return oil is added to the supply oil going to the head of the stick cylinder.

The regeneration valve allows the excavator to operate more efficiently. The main pump supply oil not required to move the stick in is available to operate another circuit.

NOTE: Stick regeneration only occurs when the position of the stick is between full stick out and stick vertical.

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Stick unloading occurs when the stick reaches vertical to the ground. Apressure spike occurs which helps to open the unloading valve to rapidly reduce rod end pressure. When the unloading valve opens, the oil flow to the stick cylinder is from the pumps.

When the regeneration valve is shifted and the supply oil to the head end of the stick cylinder is higher than the return oil from the rod end, the check valve will close.

No return oil enters the passage to the head end. As the pressure in the head end of the cylinder increases, the pressure moves the unloading valve lower.

When the unloading valve moves down, most of the return oil from the rod end of the cylinder returns to the tank past the unloading valve instead of through the stick 1 control valve.

Stick regeneration and stick unloading will not be active at the same time.

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Stick unloading occurs when the stick reaches vertical to the ground. Apressure spike occurs which helps to open the unloading valve to rapidly reduce rod end pressure. When the unloading valve opens, the oil flow to the stick cylinder is from the pumps.

When the regeneration valve is shifted and the supply oil to the head end of the stick cylinder is higher than the return oil from the rod end, the check valve will close.

No return oil enters the passage to the head end. As the oil pressure in the head end of the cylinder increases, the oil pressure moves the piston to the left which moves the unloading valve to the left.

When the unloading valve moves to the left, most of the return oil from the rod end of the stick cylinder returns to the tank past the unloading valve instead of through the stick 1 control valve.

Stick regeneration and stick unloading will not be active at the same time.

Summary of stick regeneration functions: The lack of a passage to drain in the stick 2 valve and the restricted oil flow through the stick 1 valve maintains back pressure in the rod end as STICK IN is performed.

This back pressure maintains pressure on the stick cylinder, which prevents "stick wag" from occurring. Stick regeneration allows the returning oil from the rod end of the cylinders to combine with main pump flow to move the stick cylinders out.

The unloading valve allows a means to relieve the back pressure from the returning rod end oil, when the oil is no longer needed for regeneration.

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The stick drift reduction valve is located in the stick circuit on the main control valve group as part of the stick 1 spool. The stick drift reduction valve prevents oil from leaking from the rod end of the stick cylinder. The stick drift reduction valve has the following components:

- shuttle valve

- lock check valve

- line relief valve

In the NEUTRALposition, the shuttle valve and lock check valve are closed by spring force. Oil is blocked between the stick control valve and the stick cylinder.

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For STICK OUT, the shuttle valve does not shift. The shuttle valve allows oil from the stick control valves to act on one end of the lock check valve.

Oil pressure from the stick control valves acts on the other end of the check valve. The check valve opens (due to the pressure differential on the check valve) to allow oil flow to the rod end of the stick cylinder.