What Size Hydraulic Pump Should I Use for My Log Splitter? - Backyard Boss
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What Size Hydraulic Pump Should I Use for My Log Splitter?

Log splitters are designed with a simple process in mind: to split logs efficiently. To do so, almost all use a hydraulic system to pressurize the driving force of the splitting wedge. When you purchase a log splitter, you don’t have to worry much about the individual parts other than for basic maintenance needs and cleaning purposes.

But if you are interested in building your own log splitter, which is a very realistic option due to the simplicity of the machinery, then you do need to know what parts are best for effective splitting power. Gas and electric splitters utilize a hydraulic pump which is the integral component of hydraulic power. If you were wondering what size hydraulic pump for a log splitter you need, this article explains below its use and what to look for.

How a Log Splitter Works

electric log splitter with wood and trunks

Log splitters are powerful machines that provide a splitting pressure to logs of various sizes. Almost all splitters use hydraulics whether it is pressurized via an electric, gas, or manual power source. These hydraulics feed a splitting wedge of your model of choice to make short work of just about any size log you you need to cut down to size.

One of the simplest hydraulic systems you can find in use is a log splitter. The basics of hydraulic pressure utilize an engine, oil pump to create oil pressure, a hydraulic cylinder that works with a valve for splitting power, and tank to hold and feed oil through the system.

If you are serious about making your own backyard log splitter, then you want to have, at a minimum, the following components to provide the right amount of force and power for basic splitting of averaged sized, seasoned logs:

  • A 5 Horsepower engine
  • A two-stage hydraulic pump rated at a max of 3 gpm at 2,500 psi
  • A 4-inch-diameter, 24-inch hydraulic cylinder
  • Minimum 3.5 gallon hydraulic oil tank

But you may want a bit more force for heavier workloads, which is why I’ve explained below how a pump can help determine your splitter’s speed, and influence the cutting force. Read more about how a log splitter works, how to care for it, and what you need to build your own.

Pump Size for a Log Splitter

hydraulic pump on white background

Mentioned multiple times above is the use of a two-stage pump that is most common for a hydraulic log splitter system. This is because it uses two different sets of gears doing the pumping to keep you machine running smoothly and providing the power you need at the speed you desire.

Although a two-stage pump is the best option for your log splitter, you can manipulate the amount of force it exerts through which size cylinder you choose. To calculate your own splitter’s force and speed based on the choices you make, you can use this handy calculator tool.

To watch a two-stage pump explained, watch here:

The Purpose of a Hydraulic Pump

The entire splitting system is dependent upon the pump that consists of two pumping sections and an internal pressure sensing valve. One of these sections generates the maximum flow rate rated at at lower pressure that is used to draw the piston back for the system to reset after splitting. The other section provides the highest possible pressure to generate maximum splitting force.

Splitting Power

wood splitter in action

Knowing the maximum pressure generated by a pump determines the splitting power of the pump, and one thing you will notice is that most companies are fairly generous in their tonnage claims and round up more often than not. To figure the tonnage provided by the splitter, simply multiple the maximum pressure of the pump (a two-stage pump applies about 3,000 PSI), by the total surface area of the piston in square inches. The resulting number is the total available pressure.

Flow Rate for Cycle Time

You also can determine the cycle time of a piston to figure how quickly you can work through a pile of logs. To move a 4 inch piston 24 inches (the common piston length) you need 301 cubic inches of oil. Since a gallon of hydraulic fluid takes up 231 cubic inches, you need to pump, at a minimum, 1.5 gallons of fluid to push the piston in one direction.

The flow rate of the pump is dependent on the size of the engine powering the system. If your engine is capable of providing an 11 gallon per minute rate, then it will take approximately 20 to 30 seconds to cut, and around 10 seconds to reset. Common horsepower minimum requirements for a two-stage pump are:

  • 5.5 hp. with 11 gpm pump
  • 8 hp. with 16 gpm pump
  • 11 hp. with 22 gpm pump


For a dependable machine, you want to incorporate a two-stage pump to work with whatever size engine and cylinder you decide upon for cutting wood. These keep your splitter working smoothing and efficiently, and allow you to dictate speed and force to handle whatever size job you have in mind. If you have any further questions, or want to add to this information, please do so below. And, as always, please share.