Regen Log Splitter - 20 GPM's?

The other day this question came in: Can I use the Prince LSR-3060-3 valve with a single stage 20 gpm pump?  The short answer is, No.

The longer answer is:

A regen circuit can be used to cause a cylinder to advance more rapidly than it could with pump oil flow only.  It can only be used to increase speed in the extension, not in the retract direction.

The basic idea of regen is to connect the rod end of a cylinder to its blind end or extend end, using suitable valving (see LVS, LVT and LVR Loader Valves and LSR Rapid Extend Log Splitter Valve), so the oil which normally would be returned to tank from the rod end will be combined with the pump oil.  This causes the cylinder to extend at an increased speed.  The hydraulic schematic on the bottom of the 2^nd page of this linked pdf shows the regen circuit with in the valve.

Some notes on Regen:

-       In regen, the force produced will be equal to that produced by the pump pressure based on the area of the rod.

-       Regn is usually used with cylinders that have large rods.

-       With larger rods, you need to be aware of pressure intensification.  Some applications require a relief valve on the retract port or rod end of the cylinder to handle the pressure intensification that can happen during extend.  Take for example the LSR-3060-3 Log SplitterValve.  It is going to provide extend flows up to 25 gpm with inlet flows of 4 gpm.  What would happen if you have an inlet flow of 20 gpm?  You would see extend flows attempt up to 120 gpm.  The work ports and hoses are the wrong size to handle 120 gpm.  You would see large pressure intensification.

-       Regen is typically used to get a machine or part of a machine (loader bucket tip, log splitter cylinder) into position or the force needed to perform the work is small.

-       Caution should be exercised when sizing the oil reservoir.  A cylinder with a larger rod will cause the oil in the reservoir to fluctuate more than normal.

So why does a regen circuit work?

            In a regen circuit the same amount of pressure is applied to both sides of the piston in the cylinder.  Working similar to a displacement style cylinder, the larger area (extend side) will cause the cylinder to move – extend.  The retract side or rod side doesn’t have as much area because the rod is taking up space – Force = PSI X sq inch area of rod.

I hope this is useful information for you.