timber jack won't steer when winch freespools

Caseybow123 · September 22, 2017, 04:04:42 PM

Hey all. Time to get equipment ready for the next logging season and I am having some issues with my 230 D timberjack. For some reason when the winch is in freespool position I cannot steer the machine. You could never steer and winch at the same time, but this is in freespool. There is also a 3/4 inch hose in front of the transmission that really loads up when the freespool lever is engaged. Enough that it drops the engine rpms. Any ideas?

Neilo · September 22, 2017, 04:44:03 PM

I think it is either a relief valve or o-ring failure on the winch section of the hydraulic control valves.

Relief valves should be stamped 450 or 550psi

mike_belben · September 22, 2017, 09:20:01 PM

My expectation is that a parked idling skidder thats freespooling should basically be flowing a small volume of oil through (i assume an open center system?) And at a very low pressure.. Like the amount of backpressure that hose and filter internal friction creates.. Like 5 or 10 psi.

To have it loading hard enough to shudder a hose and lug the engine is probably 1000 psi or more. The only way you get that pressure rise is to block a flow path. So im looking for spools jammed in their bore and not returning to center.. Maybe rusty or busted detent/return springs on the back of the spool? Slotted out linkage holes and whittled pins letting some valve spool drift to a half way position?

When a seal/oring/relief valve is leaking you get low pressure. Low pressure doesnt lug engines or shudder hoses. Restriction (which creates pressure and loading) does. Keep that in mind while you inspect.

Caseybow123 · September 24, 2017, 01:55:35 PM

I think that is a good bet Mike. The skidder has not seen much work for a couple years and sitting outside in the elements. Last year I found some water is the hydraulic system. After cleaning and new filter, I was hoping it would straighten itself out but it never.

mike_belben · September 24, 2017, 04:50:25 PM

Well, theory of operations helps but in truth my best tool for hydraulic repair is disassembly and inspection. One piece at a time you are verifying components and you typically find the culprit along the way. The worst is when you buy a machine dead and some other chef peed in the broth. Theres no way to know if this poppet valve goes in this bore with this spring. Those are time consuming fixes. So having the knowledge that it once ran right is a really valuable piece of diagnostic info.

Best of luck.

Coltbodi · September 24, 2017, 05:33:28 PM

I agree with mike. I don't have a skidder, but I have tractors with hydraulics. Anytime a piston isn't working, but I can see the line shaking I know there is a blockage, and it is usually in a fitting, I especially have problems with blockages in quick connects. First thing I do I take off the line that is shuddering and check both ends. The check the next line in the sequence. If I don't find a blockage I reverse the lines, that usually breaks up any blockage things go back to normal.

vasquat · October 30, 2020, 02:56:02 PM

Caseybow123,

Did you find and resolve your problem? I have a similar issue with my TJ 225. The steering and blade work at the same time. But if I free spool the winch the main hydraulic lines going in an out of the valve bank jump, the engine loads slightly, and if I try to control the blade or steer at the same time they give a little jerk then stop moving. I'm thinking I need to pull the valve bank and look at the winch valve. It would be a first for me (mechanical/hydraulic newbie) but wanted to see what you found or others thought. thanks,

Caseybow123 · October 30, 2020, 03:19:21 PM

The problem was in the main valve body. I took off, disassembled and cleaned everything. Small pieces of crude in the system. The steering, blade and hydraulic valves are all together so I cleaned them all seeing that I had taken it off in one piece anyway. When you have it he vslve bodies out and apart, it would be worth changing the o-rings. Word of advice: Clearly label all in and out hoses to it's respective hydraulic function. Hope this helps.

vasquat · October 31, 2020, 12:51:09 AM

Thanks Caseybow123? I think I'll be able to give it a go this sunday.

47sawdust · October 31, 2020, 05:39:28 AM

For marking hyd. lines and fittings to remove and re-install I use multi colored zip ties to to label everything.
A phone camera is also a big help.

mudfarmer · October 31, 2020, 10:30:38 AM

Quote from: 47sawdust on October 31, 2020, 05:39:28 AM
For marking hyd. lines and fittings to remove and re-install I use multi colored zip ties to to label everything.
A phone camera is also a big help.

Yes it is great to take a whole bunch of pics from different angles, this has helped a bunch when I forget what goes where ;D

mike_belben · October 31, 2020, 11:49:50 AM

I make myself a quick video tutorial on which way this or that goes, especially on valvebodies and such. I keep image gallery in SD storage incase phone dies.

vasquat · November 01, 2020, 11:01:19 AM

Thanks everyone for the suggestions. I took things apart with good photos and laid things out carefully.

I frankly don't know what things are called. The only issue I spotted was a destroyed seal that fits in the bottom of the cylindrical cup that sits at the bottom of the winch valve.

If I did it right I uploaded a photo showing all the parts laid out with the damages seal.

Any recommendations on where to get a seal/o-ring kit?

vasquat · November 01, 2020, 01:52:23 PM

I see one other thing that looks funny. On the top of the winch valve is 1 1/8" bolt head that is some type of flow control orifice, with a wire mesh strainer. Below the wire mesh was a bent piece of wire, maybe that is a spacer. I keep thinking I'm attaching photos but maybe they are just going into my gallery

vasquat · November 02, 2020, 08:10:57 AM

Here is a photo (I hope it works) on what I'm talking about with my text on the photo in Red. Any help is appreciated.

mike_belben · November 02, 2020, 08:50:13 AM

I suspect that wire is a piece of FOD that got through the system. Its bent like a gear tooth. I mean it could be anything.. A paperclip or cotter falls into a funnel off a bench in a shop.. Who knows. If there is no sump strainer or filler strainer its going through the pump to get chopped up.

The missing washer seems like it could be allowing the spring-centered spool lands to be misplaced by the thickness of the washer. This could potentially be allowing an unintended crossleakage.

The hoses shuddering means they are encountering a resistance to flow and raising pressure in the valve galleys and associated hoses where the rise is occuring. A spool being off center slightly blocks one passage and slightly reveals another so fluid reroutes to where it dont belong and things get difficult to figure out without test pressures and ports and shematics to study as to exactly how and why.

If you have no steering under a certain winch condition normally, that is to say your pump flow is not available to the steering cylinder(s) and this is probably also not available to the steer valve. the steer valve is evidently designed in a series circuit that lay downstream of the winch circuit. The flow has been cut off upstream of the steer valve and rerouted to do work in the winch then back to tank until you stop winching and block that route to tank. Fluid is lazy like us.. Always seeking a way to go back to bed without doing any work. If no work isnt an option, the next goal is minimal work. Maximum work is only done when there are no other options. Basically when the only way back to tank is through the cylinder or motor. The instant an easier alternative is revealed, going to work is avoided! Sounds like what stimulus checks are doing to industry dont it?

Well now with this undesigned issue you are having of no steer even in freespool.. It probably does not mean you have no FLOW getting to the steer valve.. It probably means you have insufficient pressure because a new access route to tank.. A short circuit if you will...has been provided upstream by the leak. Molecules race to the leak until the pressure in the entire system equilizes. so fluid pressure does not rise high enough to extend the steer cylinder against the resistance offered by machine mass. It (the pump flow) doesnt have to bend the machine because theres an easier way to get home (the tank) than to do hard work in the steer cylinder first.

That valve where the wire is.. Thats a nice short circuit if the seats dont seal. The wire is not in the schematic and appears to do nothing so take it out. Find a washer for the spool section and install it.. Then try again and see what happens. Dont tell yourself its fixed.. Dont make production promises and dont get discouraged when you have it all apart for the 3rd time. This is all part of the game and you are learning, youre doing good work and will lick that problem soon enough just stay persistent. Now that you know where the relief is you know where to shoot a temp gun reading to see if its a few degrees hotter.. And to listen for flow whining over the relief with a stethoscope or long screwdriver. Just hold the handle to your ear. Loudest spot is your leak. Maybe thats not the issue.. Crossing things off is how youll fix it.

vasquat · November 03, 2020, 09:08:08 AM

Thanks Mike for the advice and guidance. makes sense. I'll give it a shot.

vasquat · November 04, 2020, 04:51:17 PM

8)
Success (so far)

The service manual implied, with the exploded view, that when only one relief valve is used it should be in the bottom with a plug in the top, mine were reversed. So I:

-Removed the FOD in the relief valve
-swapped the plug and relief valve
-cleaned things (not that well)
-re-assembled

That seems to have worked. Now I can free spool and the engine doesn't load and I can steer and use the blade at the same time. I changed two things so it is not clear whether the swap or FOD removal did it. Thank you!