Adjusting the Relief Setting on Your Log Splitter Valve

Welcome back to the RuggedMade Tech Corner. I'm Jared. This is part of our series on hydraulic directional control valves. In our last episode, we looked at this -01 valve with the half-inch work ports, which is the same as our -02, except for the three-quarter-inch work ports. This is one of the most common and popular types of valves found on hydraulic log splitters, and the main reason for that is the return detent. This valve is also very similar to the Prince LS3000 [Valve], and it also has the detent. The settings for the detent and the relief are the same.

In the previous episode, we were adjusting the pressure setting on that detent, and in today's episode, we're going to go further by looking at the relief valve. The relief valve is located under this big hex cap. It consists of a few parts; there's a screw, and a spring, and a ball, and we'll see that in a moment. What it does is allow the fluid that's coming into the valve to pass right through the valve and shunt directly back to the tank instead of being forced through these work ports to and from something like a hydraulic cylinder to do work, so it basically functions as a bypass.

The relief mechanism is quite simple and shouldn't require frequent adjustments. It's pretty much set to a common pressure threshold at the factory, and that should work for most applications. But there are some situations where you may find you need to adjust it. If you have a lot of hours and cycles on your system, that could cause some wear and tear on the parts, which would change the behavior. If you are splitting in a very cold ambient temperature versus a very hot ambient temperature, your fluid and the metal spring are going to behave differently. The viscosity and temperature of your hydraulic fluid can affect how it behaves, and your particular application might require a different setting than how it came from the factory. There's no need to remove the parts from the valve just to adjust it unless you suspect some components have failed. We recommend leaving the parts in the valve, but let's take it apart anyway just so we can see what's going on inside and see how it works.

The hex cap takes a 1 1/16-inch wrench or socket. A 27-millimeter wrench will work as well. So, that's the cap. This is the adjustment screw. It takes an 8-millimeter Allen tool. At the moment, it is compressing the spring, so I'm going to throw some safety glasses on, but before this screw gets all the way out of the body of the valve, it will have released tension on the spring. At this point, there are still some threads engaging and the spring is decompressed. So that is our adjustment screw. There's our spring, and this is a tap-it kind of thing, and there is our ball.

The relief valve is not a self-contained cartridge like the return detent we looked at in our last episode, but it functions in a very similar way. This screw is going to compress the spring and keep it compressed, and that will hold this ball in position blocking an orifice. The orifice is that alternate pathway that allows fluid to head right back to the tank. If pressure in the system doesn't exceed the setting that this is set to, it will not be able to overpower the spring, and the fluid will go through the work ports and do work. But if pressure in the system exceeds the threshold determined by this relief, it will overpower the spring, dislodge the ball, and the fluid will escape through that alternate path.

Generally, you don't want the relief valve threshold set too low. If it's set very close to the amount of pressure needed in the system to do the job, then instead of doing work in the cylinder, it's just going to shunt through the bypass and go back to the tank and create heat.

Now let's adjust the valve for real. Be sure to wear eye protection when working with hydraulics, especially if you've recently touched any of the hydraulic connections. Run the machine and bring your hydraulic fluid up to normal operating temperature so that any adjustments we make to the relief valve will reflect how the system behaves during normal real-world use. As you can see, the splitter isn't able to split this very straight-grained and dry piece of wood, so the valve relief needs some adjustment. A pressure gauge can be very helpful when making adjustments like this. This pump is rated for up to 3000 PSI, so we're using a glycerin-filled pressure gauge with a range up to 4000 PSI.

So I cheated to set the relief very low to simulate a machine that's not able to split a log. If you really saw pressure this low on the gauge and you knew that your relief screw was set to a reasonable position, then it would indicate a problem somewhere else in your system, such as a failed pump. But now let's go ahead with an actual adjustment to increase the threshold for the relief valve.

Remove the cap to gain access to the adjustment screw. Turn the screw in to increase compression on the spring and increase pressure. Now that we've made an adjustment, it can split the log, and on the gauge, we see 1500 PSI.

Now keep in mind a gauge won't necessarily show the highest pressure the system is capable of, and sometimes logs split with very little pressure required, especially in the case of a splitter like this that has a five-inch ID cylinder, which brings a lot of tonnage to bear without necessarily needing that much hydraulic pressure acting in the cylinder. So now let's remove the log and fully extend the rod and see what the max pressure reading is on the gauge. And it's still 1500 [PSI], so let's make another adjustment.

So after our final adjustment, we've run the cylinder rod out to full extension, and we're reading 2500 PSI on the gauge, and that's typically the maximum pressure that you'll see on a system like this. If you need to decrease the pressure threshold at which the relief opens, back the adjustment bolt out. This will reduce the spring pressure on the ball, but make sure you don't set the relief below the pressure needed for the system to do its job, such as split a log in this case. The key is to make small adjustments.

When you're satisfied that the relief is set correctly, reinstall the cap. The area under the cap is not exposed to flowing fluid, but hydraulic fluid can seep past the adjustment bolt, so there's usually an O-ring of some kind between the cap and the body of the valve. The cap should fit snug, but don't over-tighten it.

That's how you adjust the pressure relief on this style of valve. It's easy to do, though you need to install a gauge to do it accurately.

Be sure to stay tuned to the RuggedMade Tech channel for more videos to help keep your equipment running properly. Thanks for watching.