Log Splitters FAQ

Q: I need a pump for my Log-splitter. How do I know which one?

A: To determine which pump to purchase, you will need to know the following: what HP engine will you be powering my log splitter with, what size reservoir capacity you have available, and what type of pump mount you will be using.

Q: What are the different types of log-splitter pump mounts?

A: There are two common types of mounts used on log-splitters. There is a four-bolt mount and a two-bolt mount. The four-bolt mount pumps generally come in 5gpm-16 gpm sizes and have a ½” keyed shaft about 1-1/2” long. The two-bolt mount pumps come in 22gpm and 28gpm sizes and have a 5/8” keyed shaft that can differ in length.

Q: Why is my log-splitter moving very slowly?

A: If your log splitter is moving slowly but still capable of splitting the wood it always has, it is most likely stuck in its second stage. In the second stage (or low flow/high-pressure stage), the pump produces 25% or less of its rated GPM, but it does it at a higher pressure. The transition from the first stage (or high flow/low-pressure) is an automatic process achieved via internal valving within the pump. If something within that valve has malfunctioned, it is typically more economical to just replace the whole pump.

Q: My log splitter moves normally but will not split the log. What is going on?

A: If your log splitter is operating normally but is not capable of splitting the wood it always has, it is most likely one of two problems:

1. The pump is likely stuck in its first stage if the engine bogs down and stalls out. In the first stage (or high flow/low-pressure stage), the pump produces its rated GPM, but it does it at about 400-900 psi. The transition from the first stage (or high flow/low-pressure) to the second stage (or low flow/high-pressure stage) is an automatic process achieved via internal valving within the pump. If something within that valve has malfunctioned, it is typically more economical to just replace the whole pump.
2. If the engine bogs down slightly but fails to stall out, you most likely have a bad seal on the cylinder piston. It is often more cost-effective to rebuild a cylinder than to replace it, depending on the extent of any internal damage. Consult with your local hydraulics shop.

Q: I want a more powerful pump for my log-splitter. How do they determine the sizes?

A: 2-stage log splitter pumps are sized by how many gallons per minute (GPM) they flow in the low-pressure stage. Most 2-stage Log-splitter pumps will safely create 3000 psi regardless of how quickly they transfer the fluid doing it. So, there is not actually a more “powerful” pump, just slower or faster.

Q: What size log splitter do I need?

A: The size of a splitter is typically specified in tons of splitting force. This number is determined by the surface area of the piston multiplied by the pressure applied by the pump. The tonnage you will need depends predominately on the type and size of wood you will be splitting. Hardwoods such as oak and hickory take more force to split than most coniferous softwoods like spruce and fir. The Janka rating is the measurement that they use to rate the hardness of wood. The higher the number, the harder the wood. Log diameter size is another important factor in the amount of force required to split the log. The moisture content is one of the most important factors in determining the Tonage required to split logs. See below for a decent chart for tonnage requirements for seasoned wood. You will need 50-75% more tonnage for splitting green wood.

Q: How do I know what tonnage log-splitter I have?

A: The tonnage rating on your log-splitter is determined by two distinct factors: piston surface area and pounds of force per square inch (psi) supplied by the pump acting upon that surface. To determine the piston surface area, you must take half of the bore diameter and multiply that number by itself. Then, multiply that number by pi (approximately 3.14). This will give you the surface area in square inches. Although your hydraulic pump will be rated to a certain maximum pressure rating, typically 3500psi, most log splitter hydraulic systems have a relief valve limiting the amount of pressure supplied to the cylinder and other components. To find the tonnage of your log splitter, you will take the relief valve setting in pounds per square inch multiplied by the surface area of the piston in square inches, then divide that number by 2000 pounds per ton. See the example below for a 4-1/2” cylinder at 3000psi:

Q: How do I hook up my log-splitter valve?

A: Your valve will have four ports. The IN port is supplied by the hydraulic line coming directly from the pump. The OUT port will return the flow of oil directly to the reservoir. That leaves the two work ports on the valve. The work port closest to the valve handle will be connected to the cylinder’s barrel port (extending). Attach the other valve port to the rod port (collapsing) side. See the figure below.

Q: What are my options for made-in-the-USA log-splitter valves?

A:  

• 1. Cross MFG.: Hays, Kansas
• 2. Energy MFG.: Monticello, Iowa
• 3. Prince Hydraulics: Sioux City, South Dakota

Q: How do I use my log-splitter valve?

A: Typical Log-splitter valves have three positions. Extend – Center – Retract. The extended position directs flow to where the cylinder expands, thus forcing the wedge through the log to be split. The handle must be held in this position to maintain cylinder movement. When the handle is released, the valve will spring to the center from the extended position. The retract position of a log-splitter valve has a feature commonly referred to as a pressure kick-out detent. Pulling the valve into the retract position detent will cause the cylinder to collapse until it is fully pulled in without holding onto the valve handle. Once the pump pressure builds to a pre-set amount, the internal workings of the valve will force the handle back into the center position automatically.

Q: What pressure is my log-splitter hose?

A: The hoses on your log splitter should have the rating printed or embossed onto the outside sheathing of the line. If it is not visible or readable, it is a distinct indicator of weather damage and/or rot, and you should look to have it replaced.

Your log splitter requires multiple hoses and could potentially have three different pressure ratings (see figure below). The suction line shown in green does not see any pressure, on the contrary they usually have some sort of structure to keep the hose from collapsing. The return lines shown in orange do not typically see much pressure, but they are typically rated at 350 psi. The actual pressure lines shown in red should be rated to at least 3500psi for your typical log-splitter application.

Q: What type of fluid can be used in my log-splitter? AW-32 or ATF?

A: Most Hydraulic systems can be safely operated with either ATF (Automatic Transmission Fluid) or a standard petroleum-based hydraulic oil. Some Log-splitters have a replaceable filter assembly to help clean the oil clean. If your log-splitter does not have a replaceable filter, it would be beneficial to use ATF and allow the detergents in the fluid to help keep things clean.

Q: How do I get seals for my log-splitter cylinder?

A: There are many manufacturers of log-splitters out there and just as many, if not more, manufacturers of cylinders. The only way to know for sure which cylinder you have is to contact the log-splitter manufacturer with the model and serial number of your unit and ask for a parts breakdown for their part number for the seal kit.

If this is not an option for you for whatever reason, you can disassemble your cylinder and match up the seals by example with your local hydraulics shop. If you do not have a local shop, or they do not offer this type of service, you will need to measure the hard component dimensions of your cylinder. You will then need to match them with the dimensions of available seals with a seal supplier such as Seal Source, Hercules Sealing Products, or any other national seal supplier. Many of them have an online interface to help you make this selection.

Q: How do I find a new log-splitter cylinder?

A: There are many manufacturers of log-splitters out there and just as many, if not more, manufacturers of cylinders. The only way to know which cylinder you have is to contact the log-splitter manufacturer with the model and serial number of your unit and ask for a parts breakdown for the part number for the cylinder they used on that specific unit.

Q: How do I pick a replacement cylinder for my log-splitter?

A: The first step in selecting a replacement cylinder for your log-splitter is identifying what style of cylinder you currently have. While many manufacturers utilize common-style cylinders, many do not. Please see the figures below for the most readily available styles.

If your cylinder is held together with four large bolts, you are in luck because this is the most common tie-rod style cylinder. The cylinder will have a clevis mount on the barrel end of the cylinder. The rod end mount is usually threaded to accept a clevis or possibly some other style of the end. There are not as many options in this style of cylinder.

If your cylinder has a welded body and a clevis mount on each end, it is a welded-clevis-style cylinder. The cylinder will have a clevis mount on the barrel end of the cylinder, with the rod-end mount usually threaded to accept a clevis or possibly some other style of end.

If your cylinder has a welded body and a short piece of pipe on each end, it is a welded-cross-tube style cylinder. The cylinder will have different widths on each end. You will want to pay close attention to mounting widths and pinhole sizes to ensure compatibility.

If your cylinder has a hole drilled through the rod end, this is called a pin-eye style cylinder. These cylinders are commonly available with either a clevis mount or a cross-tube on the barrel end. You will want to pay close attention to mounting widths and pinhole sizes to ensure compatibility.

If your cylinder is mounted on lugs coming out of the side of the cylinder, this is what they would call a trunnion-style cylinder. Trunnion mount cylinders are almost entirely exclusive to the log-splitter manufacturer. You will need to get a replacement from the original manufacturer or contact a machine shop to recreate the mounts on a more common cylinder.

Once you have determined the style of cylinder you are looking for, you will need to determine the bore size, the mounting pin-to-pin length (both collapsed and extended), the rod diameter, and pinhole sizes. Drawings are usually available for individual cylinders to ensure a proper fit. It might be necessary to have a local shop alter your log-splitter frame to accept the cylinder or alter the cylinder to fit your machine.

WARNING! Altering the cylinder in any way will void any factory warranty.

Q: What does GPM mean for log-splitter pumps?

A: 2-stage log splitter pumps are sized by how many gallons per minute (GPM) they flow in the low-pressure stage. While operating below the bypass setting, the pump will transfer that number of gallons per minute.

Q: Can I get a new handle for my log-spitter valve?

A: The availability of replacement parts for log-splitter valves depends on the manufacturer of the valve. You will first need to identify the manufacturer of the valve. Northern Hydraulics carries replacement handles and brackets for Cross MFG valves and replacement brackets and detents for the Energy MFG log-splitter valves

Q: How does the log-splitter valve detent work?

A: The retract position of a log-splitter valve has a feature commonly referred to as a pressure kick-out detent. Pulling the valve into the retract position detent will cause the cylinder to collapse until it is fully pulled in without holding onto the valve handle. Once the pump pressure builds to a pre-set amount, the internal passages in the valve will force the spool back into the center position automatically.