Log Splitter Problems - Please Help.

[Tom Myers]

Three weeks ago I purchased a new Lumberjack 20 ton dual action log splitter. I have split about two cords of seasoned oak and, up until today, it would walk right through anthing I could lift up onto the carriage.
Today, it started to lose power on the return stroke and, after a while, the same thing happend on the extension stroke. It will split the small stuff that but will not develop enough force to push through anything over 5 inches in diameter.

I checked the hydraulic oil and it is full and clean. My knowledge and experience with hydraulics is almost nil and I could sure use some suggestions from someone with more experience as to how to determine what is wrong.
Any help would be sincerely appreciated.

[oneokie]

Does it have a filter in the suction line from the reservoir and the pump?

[Tom Myers]

Does it have a filter in the suction line from the reservoir and the pump?

No. Just a straight shot to the pump.

[Akheloce]

Bleed the system?

[country gent]

Look in the owners manual for a trouble shooting section that lists issues and fixes. There may be a pressure regulator restrictor valve in line to regulate pressure from the pump. May be a bad seal on the pump or a actuator valve not opening completely.

[bayjoe]

Do what Akheloce says. You go air in the cylinders

[troyboy]

Air in cylinders would cause it to be jerky. Put a gauge and check your pressures. Specs should be in the manual. I would suspect a relief or seals in the cylinder.

[MtGun44]

Pressure relief valve stuck open or opening too low? I agree you need to have
a pressure gauge or two in that system.

Bill

[monadnock#5]

http://constructionmanuals.tpub.com/14050/css/14050_224.htm

You should be familiar with Pascals Law. It's easily understood, and is the basis on which your splitter operates.

[dragonrider]

If it is a two stage pump, and it should be, the valve may not be operating. That's were I would look first. If there is no filter on the return line, put one on it.

[Pb2au]

The odds are on that the valve your control lever is attached to is blowing pressure back to tank. That is to say, when in forward or reverse position, part or most of the hydraulic pressure and flow is bowing thought the seals in the valve itself and going back to tank, not the cylinder.
the odds of the cylinder seals failing ar a bit less than those in the valve.
Since it is new, I would suggest going to your place of purchase, explain the behavior, and politely ask what they would like to do to make it correct.
If they give you the cold shoulder, call the manufacturer.
if they give you the cold shoulder, and you really need the splitter, replace the valve.
i am assuming that you checked the coupler from the engine to the pump right??? If it is failed or slipping, flow and pressure will drop of course...

[retread]

+1 on that.


The odds are on that the valve your control lever is attached to is blowing pressure back to tank. That is to say, when in forward or reverse position, part or most of the hydraulic pressure and flow is bowing thought the seals in the valve itself and going back to tank, not the cylinder.
the odds of the cylinder seals failing ar a bit less than those in the valve.
Since it is new, I would suggest going to your place of purchase, explain the behavior, and politely ask what they would like to do to make it correct.
If they give you the cold shoulder, call the manufacturer.
if they give you the cold shoulder, and you really need the splitter, replace the valve.
i am assuming that you checked the coupler from the engine to the pump right??? If it is failed or slipping, flow and pressure will drop of course...

[Andy]

When I have needed to bleed the lines on my tractor hydraulics I have experienced low power in the lift cylinder, so unless I'm missing something his problem could be as simple as needing to bleed the line to the pump. I understand that they are different systems though.

I would second the motion to put a pressure gauge in line, you can get a good glycerine filled one and the appropriate fittings for less than $30 and then you'll never have to wonder how your pressure is again. This will help with diagnostics for the lifetime of the system so it really is worth putting it in at the first problem.

I'm sure you've thought of this but if the equipment is that new you might see if it is still under warranty. I like learning to fix my own things but if I had a three week old item fail you can bet I would be calling the manufacturer about it.

I see that you are Minn. and I'm guessing that it is just starting to get cold there (like it is here), what sort of hydraulic fluid are you using? Most anything should be fine at october temps but maybe if something inappropriate was in there it could cause an issue now that it is colder. I have only had problems below 0 with some brands and not with others so this probably isn't your problem, but worth knowing your fluid in either case.

[oldred]

Fellows this is not a brake system, there is NO WAY air is the problem unless the reservoir is empty and the pump is sucking air in which case it would be making a terrible whining sound!! This is a simple open loop type hydraulic system with a two way cylinder, the oil is sucked out of the tank, pumped through the control valve and into the cylinder with the excess being returned to the tank through the pressure relief valve, you could start out with the air lines and cylinder full of air and since the fluid is flowing in only one direction from the pump in only a few seconds the air would be gone, it would simply be exhausted into the tank with the return fluid! Air could be a problem on a one way system where the cylinder is only pressurized in one direction (a cylinder with only one hydraulic hose) and has to rely on gravity or a spring for return but not on a full hydraulic circuit like this.

Pb2au most likely nailed it, there could be a couple of other reasons why this might happen but that is the most likely, for SURE it is not air in the lines and cylinders and any attempt at "bleeding" would be a messy waste of time.

Since this is a new machine I am going to guess there is junk in the hydraulic tank, welding slag and spatter from building them is common, in any case it's likely there is a piece of debris stuck under the relief valve. This valve is usually nothing more than a steel ball pressed against a seat by a heavy spring, when the pressure reaches it's design maximum load due to resistance on the cylinder the spring pressure is overcome and fluid is bypassed back to the tank. This necessary because without this valve under too much load the pressure could continue to increase until something either blows out or breaks or the motor stalls, if even a tiny piece of dirt, slag or a tiny metal chip is caught under that ball it will allow fluid to pass through without having to compress the spring, this will happen at low pressure and will not allow maximum pressure to be reached resulting in exactly the problem described. I think this is the most likely cause since the equipment is new and seals, valve spools, etc have not had time to wear but of course they could be scratched from the same contamination that would cause the valve to leak. None of this should occur since there should be a screen over the suction line that would not allow debris to pass through, at least not big enough to cause the problem, but then things like log splitters are not always well thought out when building nor is there usually a lot of care taken during construction.

[Tom Myers]

Thanks everyone for the provided insight and direction.

Your advice, when considering the relative newness of the unit and the existing problem, seems to indicate that the most probable cause is an over pressure valve that is not closing properly.

Before attempting any repairs, I will call the dealer this morning and explain the situation. This should give a good indication of just how good the warranty is.

In case I get no satisfaction from the dealer, would the location of the over-pressure valve be in the pump or in the control valve?

There is no filter in the line and no pressure guage so, after correcting the main problem, the first order of business will be to locate and install a filter and guage.

Would I be right to assume that the pressure guage is installed in the line between the pump and the valve and the filter, of course between the hydraulic tank and the pump?

Sure hope I can get this unit up and running again soon. I've another 7 cords of oak logs to cut and split and, when this thing is working right, it's the best thing to come along since sliced bread.

In case it might provide more insight, I am enclosing a schematic of the layout of the splitter.
Click on the image to see a larger version.

119011

Thanks again for all the help and advice. I will post updates on the progress of solving this problem.

[oneokie]

Most likely, the pressure relief valve is in the control valve. If it is a 2 stage pump, there will also be a pressure valve in the pump.

With a 2 stage pump, one should hear a change in the sound of the engine when the second stage of the pump kicks in. This will happen when the ram encounters heavy resistance (knot or fork (crotch) in the wood)

The filter shold be installed in the suction line between the reservoir and the pump, so as to keep debris from entering the pump. Most wood splitters have what is called an "open center" system. ie, hydraulic fluid continually circulates through the system until the control valve is operated, thus changing the flow of the fluid, redirecting it to the cylinder, either extending or retracting the ram.

[tomme boy]

Nope, the seal on the piston in the cylinder is leaking. So the pressure is going both ways. I have rebuilt hundreds of hydraulic cylinders. perform all checks first, but I bet it is the seal.

[oldred]

Nope, the seal on the piston in the cylinder is leaking. So the pressure is going both ways. I have rebuilt hundreds of hydraulic cylinders. perform all checks first, but I bet it is the seal.

If it were older machine I would agree but unless the cylinder is severely scored from debris a new one is not going to be worn out and simply repacking it won't help, besides this was a rather abrupt failure. This is MUCH more consistent with debris in the system rather than a worn cylinder packing. Also the filter should be on the return side (that's why they are called return line filters :mrgreen:) rather than on the suction side, usually a suction STRAINER is installed where the line connects to the tank. If the filter is installed on the suction side (as is the case on some poorly designed log splitters but not decent well engineered equipment) it can, and will, cause cavitation to occur in the pump when it starts to restrict the flow due to normal clogging, it can cause far more problems in that location than it can solve!

Straight out of a hydraulics handbook,

[Return filtration: The rationale for locating filtering media in the return line is this – if the reservoir and the fluid it contains start out clean, and all air entering the reservoir and returning fluid is adequately filtered, then fluid cleanliness will be maintained. The other advantage of the return line as a filter location is that sufficient pressure is available to force fluid through fine media (typically 10 microns), but pressure is not high enough to complicate filter or housing design. This, combined with relatively low flow velocity, means that a high degree of filtering efficiency can be achieved at an economical cost. For these reasons, return filtration is a feature of most hydraulic systems.]

[Suction filtration: From a filtration perspective it would seem that the pump intake is an ideal location for filtering media. Filter efficiency is increased by the absence of both high fluid velocity, which can disturb trapped particles, and high pressure drop across the element, which can force migration of particles through the media. But these advantages are outweighed by the restriction the element creates in the intake line and the negative effect this can have on pump life.]

That last line, "But these advantages are outweighed by the restriction the element creates in the intake line and THE NEGATIVE EFFECT THIS CAN HAVE ON PUMP LIFE", is the reason the filter should not be installed on the suction side because cavitation will wreak havoc on a pump in short order! These filter units are almost always equipped with a bypass valve because they will tend to clog and need periodic changing, the bypass is usually about 5 to 7 lbs which will show up as back-pressure on the return side, this 5 to 7 PSI positive back-pressure will not cause problems but 5 to 7 lbs of negative pressure on the suction side is disastrous to the pump due to the cavitation it will cause. Obviously it's normal for the filter to clog otherwise they would not need periodic changing, think about what happens when the pump is trying to suck fluid through a clogged filter!


There are suction line filters available that have the advantages of the suction location but these are large, complicated and expen$ive! The trick is to use a return line filter with a simple replaceable screw on filter rated at around 10-20 microns and a strainer in the tank at the suction port and in the filler neck to catch anything before it enters the tank.

I stand corrected.

[Tom Myers]

Wow. Who would'a thought. I'm learning a bunch.

Called the warranty shop that handles these machines and they were polite and positive. The man said "Bring it in right away so we can get to work on it."

Another problem. The ball hitch socket does not work. No way could I get it to release. I don't have time to mess with it and, by luck, have an old camping trailer with a reliable, working hitch that bolted right on. So I'll be heading for the repair shop in Brainerd after lunch. I'll get the machine in for repairs and then have another look at the hitch that doesn't work.

[Tom Myers]

I just returned from dropping off the splitter at the warranty repair shop.

Althought not directly stated, while speaking with the service manager and without an examination of the machine, he implied that improper cylinder seal installation is the common cause when these units fail. Instead of just authorizing a replacment of the cylinder seals, the manufacturer sends out a replacement cylinder as a matter of course.

So, my plans of taking advantage of the next week of prediced balmy weather to substantially increase the winter firewood supply will need to be put on hold for the next week to 10 days.

Thanks everyone for all the knowledge and advice. If a new diagnosis is made for the sick machine, I'll let everyone know.

[oldred]

A failed seal due to improper installation would be a "best case" scenario since that would mean no real damage has occurred, even if parts of the packing have sheared off and are in the system they are soft and won't scratch anything so they should not cause any future problems except for maybe with the relief valve but that is an easy fix. I have seen seals damaged by ham-handed installation but they almost always show the problem immediately, I suspect that since they seem to be aware of a "common" problem and want to replace the entire cylinder rather than just repacking it then it's possible the cylinder bore is over-sized. The fact the cylinder worked for a while and then failed makes this even more likely but in any case it sounds as if they are going to fix the problem for you, let's hope they do so quickly.


Just as with most other products there have been some rather dubious pumps and cylinders from China in the last few years so I suppose anything is possible.

[geargnasher]

New equipment slapped together with dirty Chinese components and without a good quality return-side hydraulic filter is a recipe for early failure of a lot of things. I see a whole lot of this at work, scarred cylinder bores, valve bodies, valves, and stuck pressure-relief valves are the norm as there is so much manufacturing grit/shavings/wire strands/metal flakes/etc. throughout the system from the new components and it just keeps getting cycled through the works over and over.

Many log splitters have a special valve that kicks to reverse at a certain pressure point and that auto-reversing shuttle is very vulnerable to debris/wear affecting it's "tuning". If you can disassemble and clean a bullet mould or a 1911 you can pull apart the hydraulic control valve and have a look at things inside. Generic Hydraulic filter heads are also widely available, inexpensive, (less than a filter), and can usually be plumbed in easily if you have just one short hose made, or sometimes even just a pipe nipple is all that's needed to connect it in between the return hose and the reservoir. Hoses can be made by most auto parts stores for less than $50 if it's 3/4" pipe threads, stick with straight because the angled fittings are 2-4 times as expensive. Hardware store pipe fittings are plenty strong enough for return-side pressures.

Contact me if you get stumped on a filter head number, I can look something up in Wix, Fleetguard, Baum, etc.. You'll probably want to change the fluid when you get the machine back, too, although they'll lose a lot of it when they change the cylinder, just hope they put new in and don't catch it in a dirty pan and return it to the reservoir.

Gear

[MaryB]

See if they have a loaner splitter to keep you cutting and taking advantage of the weather.

[Mk42gunner]

See if they have a loaner splitter to keep you cutting and taking advantage of the weather.

Best idea yet. Why should you have to squander the good weather because of warranty problems?

Robert