Log splitter valve

Conventional log splitters feature a differential valve. It is used to enable the accelerated extension of the log splitter cylinder. Without this so-called “high-speed/low-speed valve,” both the extension and retraction of the cylinder would occur based on the defined pressure and flow rate of the hydraulic system. As a result, the splitting and resetting processes of the cylinder would run at the same, relatively slow speed.

The differential valve used ensures that, with a piston-to-piston-rod ratio of 1:2, the cylinder extends at double the speed and half the force up to a certain, preset pressure. Deviations from this rule are to be expected if the hydraulic cylinder used does not have an area ratio of 1:2. Due to the design of the “high-speed/low-speed valve,” using the high-speed mode during the retraction of the log splitter valve is unfortunately not possible.

Operation of the log splitter valve

The cylinder extends in high-speed mode. During this process, the lever is pushed toward the log splitter valve. If the splitting wedge does not have enough force upon reaching the piece of wood, the lever must be operated to the stop. This ensures that the cylinder works with full force and half speed. After the splitting process, the lever is pulled from the log splitter valve and the lever clicks fully into place.

Once the cylinder end position is reached, the splitter lever jumps to neutral and the hydraulic system pump runs in a pressureless circulation. This function allows the piston to reset without operating the lever. This enables the operator to prepare a new log during the resetting process.

Function of the log splitter valve

The valve of a log splitter has three main positions, which are briefly explained below. In position A, the control lever is pulled down and the cylinder extends. This moves the splitting wedge toward the log in high-speed mode. If the lever is released, the log splitter valve is in position 0. The cylinder remains in position 0 and the splitting process is finished. If the log splitter lever is pushed up, the cylinder retracts and unlocks automatically when the cylinder is fully retracted. This position B marks the end of the splitting process.

Example of a log splitter valve

When using a differential valve, the extension time of an exemplary log splitter hydraulic cylinder with a piston-to-piston-rod ratio of 1:1.56 is reduced from 9.5 seconds to 3.5 seconds. It is assumed that the cylinder is driven at 56 liters per minute. The shortened extension time of 3.5 seconds can only be expected if the hydraulic cylinder does not have to switch to pressure.

Other environmental factors and real operating conditions can lead to a longer or shorter extension time. This also depends specifically on the setting of the switching pressure used. If the resistance at the hydraulic cylinder increases, more force is required to carry out the splitting process. Consequently, the extension speed decreases to the original speed, and the full force of the log splitter becomes available.

The switching pressure is usually configurable, so that on these differential valves, the point at which full force should be applied can be adjusted. On conventional log splitters, the switching pressure can be configured using an adjustment screw located on the log splitter valve. Additionally, there is a pressure gauge connection on a high-speed/low-speed valve. The switching pressure of the system can be set at this connection using, for example, a so-called Lo-Com pressure gauge.