wood splitter hydraulic pump problems free sample

The hydraulic pump controls the flow of fluid within the pump system. Most log splitter hydraulic pumps will be two-stage pumps, meaning that they can force the liquid within them to move in two different directions, which allows for the hydraulic arm to be pushed forward to split wood, and also retracted so the machine can be reloaded with a new log. The seals on these pumps wear over time and eventually can cause hydraulic fluid to leak out of the system. If fluid is leaking from your pump, disassemble it and replace all seals. When repairing a damaged pump it is important to carefully analyze and address the rest of the hydraulic system. When the pump fails it will often send metal debris throughout the hydraulic system. At a minimum it will be necessary to thoroughly flush the hydraulic fluid and replace the filter. Debris left in the system can quickly ruin a new pump.

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 do you have available, what type of pump mount you will be using?

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.

A: If your log-splitter is moving slow 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 with in the pump. If something within that valving has malfunctioned, and it is typically more economical to just replace the whole pump.

1. If the engine bogs down and stalls out, the pump is likely stuck in its first stage. In the first stage (or high flow/low-pressure stage) the pump produces its rated GPM but it does it at about 400-900psi. 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 with in the pump. If something within that valving has malfunctioned, and 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.

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.

A: The size of 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 amount of tonnage that you will need depends predominately on the type and size of wood that you will be splitting. Hardwoods such as oak and hickory take more force to split than most coniferous soft woods 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. One of the most important factors in determining the Tonnage required to split logs is the moisture content. See below for a decent chart for tonnage requirements for seasoned wood. You will need 50-75% more tonnage for splitting green wood.

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 take that number and multiply 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 example below for a 4-1/2”cylinder at 3000psi:

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 barrel port (extending) on the cylinder. Attach the other valve port to the rod port (collapsing) side. See the figure below.

A: Typical Log-splitter valves have three positions. Extend – Center – Retract. The extend 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. The valve will spring to center from the extend position when the handle is released. 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.

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 them 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 for pressure, but they are typically rated to 350 psi. The actual pressure lines shown in red should be rated to at least 3500psi for your typical log-splitter application.

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.

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 that 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.

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 that 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 cylinder that they used on that specific unit.

A: The first step in selecting a replacement cylinder for your log-splitter is identifying what style of cylinder that 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 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 bore size, the mounting pin to pin length (both collapsed and extended), the rod diameter, and pin hole sizes. Drawings are usually available for individual cylinders to insure 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.

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.

A: 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

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.

The second leading cause of hydraulic pump failure, behind contamination, is cavitation. Cavitation is a condition that can also potentially damage or compromise your hydraulic system. For this reason, understanding cavitation, its symptoms, and methods of prevention are critical to the efficiency and overall health of not just your hydraulic pump, but your hydraulic system as a whole.

The product of excessive vacuum conditions created at the hydraulic pump’s inlet (supply side), cavitation is the formation, and collapse of vapors within a hydraulic pump. High vacuum creates vapor bubbles within the oil, which are carried to the discharge (pressure) side. These bubbles then collapse, thus cavitation.

This type of hydraulic pump failure is caused by poor plumbing, flow restrictions, or high oil viscosity; however, the leading cause of cavitation is poor plumbing. Poor plumbing is the result of incorrectly sized hose or fittings and or an indirect (not straight or vertical) path from the pump to the reservoir. Flow restrictions, for example, include buildup in the strainer or the use of an incorrect length of hose or a valve that is not fully open. Lastly, high oil viscosity—or oil that is too viscous—will not flow easily to the pump. Oil viscosity must be appropriate for the climate and application in which the hydraulic pump is being used.

The greatest damage caused by cavitation results from the excessive heat generated as the vapor bubbles collapse under the pressure at the pump outlet or discharge side. On the discharge side, these vapor bubbles collapse as the pressure causes the gases to return to a liquid state. The collapses of these bubbles result in violent implosions, drawing surrounding material, or debris, into the collapse. The temperature at the point of implosion can exceed 5,000° F. Keep in mind that in order for these implosions to happen, there must be high vacuum at the inlet and high pressure at the outlet.

Cavitation is usually recognized by sound. The pump will either produce a “whining” sound (more mild conditions) or a “rattling” sound (from intense implosions) that can sound like marbles in a can. If you’re hearing either of these sounds, you first need to determine the source. Just because you hear one of these two sounds doesn’t guarantee that your hydraulic pump is the culprit.

To isolate the pump from the power take-off (PTO) to confirm the source, remove the bolts that connect the two components and detach the pump from the PTO. Next, run the PTO with no pump and see if the sound is still present. If not, it is safe to assume your hydraulic pump is the problem.

Another sign you may be experiencing cavitation is physical evidence. As part of your general maintenance, you should be inspecting and replacing the hydraulic oil filter"s elements at regular intervals based on the duty cycle of the application and how often it is used. If at any time during the inspection and replacement of these elements you find metallic debris, it could be a sign that you’re experiencing cavitation in the pump.

The easiest way to determine the health of your complete hydraulic circuit is to check the filter. Every system should have a hydraulic oil filter somewhere in-line. Return line filters should be plumbed in the, you guessed it, return line from the actuator back to tank—as close to the tank as possible. As mentioned earlier, this filter will have elements that should be replaced at regular intervals. If you find metallic debris, your pump could be experiencing cavitation. You’ll then need to flush the entire system and remove the pump for inspection.

Conversely, if you’ve already determined the pump to be damaged, you should remove the filter element, cut it open, and inspect it. If you find a lot of metal, you’ll need to flush the entire system and keep an eye on the other components that may be compromised as a result.

Once cavitation has been detected within the hydraulic pump, you’ll need to determine the exact cause of cavitation. If you don’t, cavitation can result in pump failure and compromise additional components—potentially costing you your system.

Since the pump is fed via gravity and atmospheric pressure, the path between the reservoir and the pump should be as vertical and straight as possible. This means that the pump should be located as close to the reservoir as is practical with no 90-degree fittings or unnecessary bends in the supply hose. Whenever possible, be sure to locate the reservoir above the pump and have the largest supply ports in the reservoir as well. And don"t forget, ensure the reservoir has a proper breather cap or is pressurized (3–5 PSI), either with an air system or pressure breather cap.

Be sure the supply line shut-off valve (if equipped) is fully open with no restrictions. This should be a “full-flow” ball valve with the same inside diameter (i.d.) as the supply hose. If feasible, locate a vacuum gauge that can be T’d into the supply line and plumb it at the pump inlet port. Activate the PTO and operate a hydraulic function while monitoring the gauge. If it reads >5 in. Hg, shut it off, and resume your inspection.

A hose with an inner bladder vulcanized to a heavy spiral is designed to withstand vacuum conditions as opposed to outward pressure. The layline will also denote the size of the hose (i.d.). You can use Muncie Power’s PPC-1 hydraulic hose calculator to determine the optimal diameter for your particular application based on operating flows.

Another consideration, in regards to the inlet plumbing, is laminar flow. To reduce noise and turbulence at the pump inlet, the length of the supply hose should be at least 10 times its diameter. This means that any type of shut-off valve or strainer at the reservoir should be at least 10 diameters from the pump inlet. A flared, flange-style fitting at the pump inlet can also reduce pump noise by at least 50 percent compared to a SAE, JIC, or NPT fitting.

Selecting the proper viscosity of hydraulic fluid for your climate and application is also critical. Oil that is too viscous will not flow as easily to the pump. Consult your local hydraulic oil supplier for help selecting the optimal fluid viscosity.

By maintaining a regular maintenance schedule, remaining vigilant for any signs or symptoms, and taking preventative measures, the good news is that you should be able to prevent cavitation and experience efficient operation for the duration of your pump’s lifespan.

Poor plumbing is the leading cause of cavitation and can be prevented by selecting a properly sized hose, choosing the appropriate fittings, ensuring the most direct, straight routing from the pump to the reservoir, etc.

The cylinder is driven by hydraulic oil, under pressure, produced by a hydraulic pump. An engine, or electric motor, drives the pump shaft, and supplies the power for the system. The oil from the pump runs to a hydraulic valve, which provides control over the movement of the cylinder.

The oil source is a hydraulic reservoir (tank) which is connected directly to the inlet port of the pump. Most use AW32 viscosity (approx 10 wt.) hydraulic oil, which is of course an important part of any hydraulic system. There is a vented filler cap on the reservoir which allows air to “breathe” in and out. A simple air filter in it keeps dirt out.

A hydraulic relief valve controls the maximum pressure which can be created by the pump, and is a safety valve. It is usually located within the housing of the directional control valve. It is rarely in the pump. Without a relief, most hydraulic pumps will build pressure until something breaks, like a hose, or the cylinder, or the pump itself.

Most log splitters use a 2-stage gear pump which is a special type of hydraulic pump. They are rarely used in any other hydraulic systems. But they are widely available and relatively cheap because so many are sold for logsplitters.

Let’s start with the basics. Gear pumps are the most common, and least expensive type of hydraulic pump. They consist of 2 shafts, each with a gear which meshes with its twin to drive oil from the inlet port to the outlet or pressure port. Oil is trapped in the cavities between the gear teeth and carried around the outside of the gear toward the outlet port. The meshed gear teeth in the center keep oil from returning to the inlet side. One shaft sticks out of the housing and is driven by the engine. The other shaft is hidden within the pump housing. The one gear drives the other.

Two stage pumps give splitters great performance using small engines. A 2-stage pump consists of 2 gear pumps in a single housing, and a bypass valve. One gear set is about 3 times the size (length) of the second. When the valve is in neutral & system pressure is low, both gear sets are pumping oil into the system. With a “16 GPM” pump, they will pump 16 GPM when the pump shaft is rotated (by the engine) at 3400 RPM. That is, the combination of the outputs from both gear sets equals 16 GPM.

When the valve is shifted it moves the cylinder quite quickly. But when the log hits the wedge, the resistance increases, and pressure is backed up against the pump. Now the bypass valve comes into play. When the back pressure reaches 700 – 800 PSI, oil from the larger set of gears is allowed to pass back to the inlet side of the pump (at almost 0 PSI) rather than being forced out the pressure port. So the only oil being forced out is from the small gear set. This takes a lot less horsepower and allows the use of a reasonably small engine to develop the high pressure necessary to split wood, while giving the cylinder good speed when not under a heavy load (which is most of the time). The opening and closing of the bypass is automatic, activated by the oil pressure. It’s so smooth it’s usually difficult to notice it is happening. So 2-stage pumps give our log splitters the best of both: high pressure when we need it, and high speed the rest of the time.

We sometimes see home made log splitters with single stage pumps, often reused from another type of machine. They are usually quite slow unless a much bigger than normal engine is used.

The cylinder is the “actuator” of the system: it converts the hydraulic pressure and flow into force to split the wood, and speed to make it efficient. The larger the cylinder diameter the more force (tonnage) it puts out, but the slower it will go: it takes more oil to fill, and so takes longer.

The most common size for log splitters is “4 x 24″, 4″ bore by 24″ stroke. With 2500 PSI from the pump it can exert over 31,000 lbs of push force. To compare, a 5″ bore cylinder can produce 49,000 lbs force with the same pump, over 1 1/2 times as much. But the 5” cylinder will go 36% slower, which is why they are not common on ordinary splitters.

Yes, I know, there are plenty of log splitters rated for much more force. And my 4 cylinder Toyota may be rated for 140 MPH. It’s a sales game. The big numbers are theoretical maximums, not practical working pressures.

1. Pushed one way it shunts oil from the pump to the base port of the cylinder, causing it to extend. And it simultaneously allows oil from the rod-end port of the cylinder to flow into the return line.

2. When let go, the spool springs back to the neutral position; the oil from the pump is allowed straight through to the return port where it is recycled back to the tank, and the cylinder ports are blocked so the cylinder is stopped and held in position.

The relief valve consists of a heavy spring with a compression adjustment screw, and a ball or poppet against a seat. This is in a channel between the pressure inlet port and the return port, with the ball or poppet blocking the flow. If the oil pressure reaches the adjustment setting, perhaps 2500 PSI, it overcomes the spring pressure, the poppet backs off, and oil from the pump is allowed to bypass directly to the valve outlet, thus limiting the maximum oil pressure in the system. At normal working pressures, the relief remains closed and is not involved in the circuit.

The hydraulic oil for the system is stored in a tank, usually steel. Reservoirs serve two important functions: They allow the oil to settle any air bubbles and contamination particles; and they allow the oil to cool while it’s not circulating.

To provide sufficient cooling, the tank should be sized to hold at least one minute’s worth of oil. (16 gallons for a 16 GPM pump.) Oil which is too hot, 180F, will harden seals, and will be too thin to lubricate the spinning pump parts, causing early pump failure. We recommend 150F as the working maximum oil temperature.

The suction and return ports should be on the sides of the tank, a couple of inches above the bottom to avoid any sludge which may have settled there. The suction line should be low enough to never ingest any air, and the return should be low so as not to stir any air into the oil. Further, the 2 ports should be separated enough to avoid the hot returning oil from being immediately sucked back into the pump line.

Every good hydraulic system has a filter to remove fine contamination particles from the oil. The recommended rating is 10 microns, (10 microns equals 0.00039 inches; about 1/5 the diameter of a human hair). A filter this fine would plug the suction line, so it must be installed on the return, typically right at the tank return port.

Suction strainers in the tank are 100 micron or more, so can not catch the fine, damaging particles like the return filter. And if they get plugged they may starve the pump, greatly shortening its life. They are not recommended.

Hydraulic oil is blended with chemical additives beneficial for hydraulic systems. They help resist wear, shed contamination, maintain viscosity when cold, resist foaming, rust and oxidation, etc. Typical viscosity is around SAE 10, usually labelled AW32.

Hydraulic oil is not subjected to the burning temperatures of combustion engines, so it usually lasts a long time. The recommendation is to change oil if it is excessively dirty, or milky (water contamination) or smells bad or burned. If not, it’s better to just change the filter and save the cost of an oil change.

How to get more force? Either more pressure, or a larger cylinder. The pressure you probably can’t change much. Check the relief setting on your directional valve. It controls the maximum. We don’t suggest more than 2500 PSI, which is the practical maximum for most gear pumps. Yes they are sometimes rated at 3000 PSI or more. But that’s like driving your car 125 MPH. It may be able to do it, but all the time? Not such a good idea. Virtually all logsplitter pumps are rated for the same pressure. What’s the difference between pumps? Bigger gears, which produce more flow, which means more speed. And requires more horsepower to drive them. To get more force, you’ll need a larger bore cylinder. If you want the same speed as a smaller cylinder, you’ll need a larger pump, and probably a larger engine to drive it.

How to get more speed? Either more flow (GPM), or a smaller cylinder. The smaller cylinder won’t require more power, but will produce less force. More flow comes from a larger pump. So you’ll get the same force but will need to supply more horsepower to the new pump.

One other factor to consider for log splitter cylinders is the rod diameter. The larger the rod, the faster the cylinder will retract. (It takes less oil to fill the return end of the cylinder.) Of course it also increases the cost of the cylinder, but if you have the choice, choose the cylinder with the larger rod.

IMPORTANT! Never operate a log splitter without the appropriate amount of approved hydraulic fluid in the reservoir tank. Operating a log splitter without sufficient reservoir fluid in the hydraulic system may result in severe damage the hydraulic pump and would be reason to void the factory warranty.

DO NOT MIX DIFFERENT TYPES OF HYDRAULIC FLUIDS. Use only one type of an approved lubricant. If the type of fluid already installed in a unit is unknown, the recommended procedure is to drain that fluid completely and refill it with all of the same type fluid.

Our log splitters have varying fluid capacities depending on the model and style. Most units have either a 3.5 gallon, 4 gallon, or 7 gallon reservoir. Please refer to the appropriate product Operator"s Manual to determine the capacity of the hydraulic reservoir of a particular model.

These fluids are all non-foaming hydraulic fluids and available from our Online Parts Store, most hardware stores, automotive supply, farm equipment retailers, and other major home improvement supply stores.

Keep in mind that the volume of the reservoir tank is less than the unit"s total fluid capacity. Fluid also needs to be primed into the hydraulic system (hoses, filter, valve, pump & cylinder), which may require as much as an extra gallon when filling the complete system.

To prime the hydraulic system, fill the fluid to the appropriate level as instructed in your Operator"s Manual. Disconnect the spark plug wire and ground it against the engine. Then pull the starter rope on the engine 10 to 15 times. This will allow the pump to push fluid into these other areas of the hydraulic system. Your reservoir level should go down, so you will need to re-check it and fill to the appropriate level.

Before splitting any wood, you should extend and retract the wedge at least 12 cycles* to remove any trapped air in the system. Again, check and fill reservoir as needed.