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WM LT40 Hydraulic System Electrical Components Maintenance

Started by pnyberg, May 24, 2011, 08:35:43 AM

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pnyberg

Now there's a mouthful.  I had to do some maintenance chores yesterday and today, and as a result I've got a story, some observations, and a question.  Just to set the background, all this relates to my 2009 LT40 standard hydraulic with the command control station.

I was milling a bunch of maple logs on Sunday, when suddenly my hydraulic pump started running constantly.  Way back, I think it was Tom who suggested adding an indicator light in the pump circuit so you'd know if this was happening, and I'd thought about doing it, but it would have been unnecessary since the pump is plenty loud enough to hear when it's running.

I shut down, gave a short explanation to the customer, and thought a minute about what I should do.  I started by removing the access panel and looking in the lower half of the control station.  The micro-switch is right there, so I thought I'd pull it out and see if I could determine if it was working properly.  The switch is attached to the end of the lever assembly by two small bolts.  I loosened these, but couldn't get them out, so the switch stayed attached.

Since I wasn't getting anywhere at the control station, I turned my attention to the pump box.  After I removed the top cover and poked around a little, I turned the key to the aux position and was surprised that the pump did not turn on.   I turned the key off again and back to aux, and now the pump started to run.  There was a bit more fiddling, but in a short time it seemed pretty clear to both me and the customer that we were dealing with a bad solenoid.   I was pleased to be able to diagnose the problem, but not so pleased that the solenoid failed with less than 300 hours on the mill.

I could sense the customer bracing himself for the disappointment of having the day cut short.  He suggested, at least half in jest I think, that one of his sons could stand next to the pump box for the rest of the day and tap on the solenoid as needed.  I responded that as an alternate approach, I could replace the solenoid.  He seemed both surprised and impressed that I would have a spare, which is exactly what you'd hope for in terms of customer reactions.

At the time, my mind-set was that if I couldn't fix the problem I'd have to pack up and go home, but in retrospect, I'm wondering if letting the pump run constantly for a few hours would have been OK.

When I pulled out my box of spare parts, I was relieved to find that there was a solenoid in there, and that it seemed to match the one in the pump box.  I did a quick wiring diagram in case of memory failure, and swapped the old for the new.  In putting everything back together I found that just as I couldn't get the micro-switch free, now I couldn't get it firmly reattached either.  The little bolts wouldn't tighten.  Things seemed to work though, so I buttoned everything back up and went back to sawing.  Overall down time was about 40 minutes.

For the rest of the day, the only odd behavior was that occasionally pushing the clamp lever down did not engage the hydraulic pump.  For some reason, if I fiddled with another lever I could always get the clamp to work OK on a second try, so we made it through the end of the job.

This morning I ordered a replacement for the spare solenoid, and then decided that I needed to figure out what's up with the micro-switch.  I pretty quickly figured out that the small bolts holding the switch to the end of the valve assembly had loose nuts on the back side.  Once loose, the nuts turned with the bolts, so I could neither get them completely free, nor re-tighten them.  If I could get to the nuts and hold them, I would be able to do either, but they seemed completely inaccessible.  

I started taking things apart.  I detached the lever assembly from the front of the control station.  This allowed me to move the assembly around some, but not enough.  I then dismantled the control station box itself, removing the bottom-back section where the umbilical sleeve attaches.  That done, I could put the entire lever assembly on the ground (on a board) next to the hitch.  That was a lot of work, but access is pretty good now.

At this point, I started to wonder what it would take to replace the micro-switch.  (I know these go bad too.)  I've got a spare one of these too, but from everything I can see at the moment, the original looked hard-wired.  I discovered the push-connectors about 6" down the umbilical.   There was enough slack in the other end of these wires inside the pump box to allow me to slide them up the umbilical to the point where the connectors will be accessible in the control station.



Then I took a look at my spare micro-switch and discovered that as shipped, the ends of the leads had eyelet connectors, but there were crimp-on push connectors included in the bag.  I changed connectors, tested the switch, and  put it back in my spare parts box.

In putting everything back together, I found that just a bit of pressure from my finger tip on the tiny nuts behind the micro switch was enough to allow me to tighten the tiny bolts.  So now replacing the micro-switch should only take a minute or two if I could only get my finger tip behind it without taking the half the control station apart.   Can anyone suggest an easier way to do this?

Thanks,
   Peter  
No longer milling

pineywoods

Peter, don't even think about leaving the hydraulic pumps running while you continue sawing. Two problems doing that.
1..Just a few minutes will drain the battery completely. No way will the alternator keep up
2..You will probably have a burning smoking mess rather quickly. The drive motors on the hydraulic power pack is basicly a ford truck starter motor. They will over heat quickly if left running. The seal on the drive shaft for the pump is plastic. Doesn't take much to melt it with resulting fluid leak.
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

terrifictimbersllc

Congratulations! Now you know how to change the micro switch, and why one would hope not to have to. Maybe make your own access panel right beneath the switch?   Or once you get a mouse in there,  train him to help you (but grind off his front teeth first).

Looks like your rocker arms have improved set screws to tighten them to the rod.   Not clear to me that anything was wrong with the switch, the problem of having to push a different lever than the one you need, to get the pump going, is consistent with just needing to adjust the rocker arm on the desired control.
DJ Hoover, Terrific Timbers LLC,  Mystic CT Woodmizer Million Board Foot Club member. 2019 LT70 Super Wide 55 Yanmar,  LogRite fetching arch, WM BMS250 sharpener/BMT250 setter.  2001 F350 7.3L PSD 6 spd manual ZF 4x4 Crew Cab Long Bed

LeeB

To me, it'svery much consistant with the micro switch being loose. I have the same problem with my mill and the clamp. I have to adjust the microswitch every time. Made the mistakeoftaking it  off once, Like to nevergot it back on with my big fingers.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

BBTom

I had enough problems with the Micro-switch five or so years ago that I drilled a hole in the panel above the levers and mounted a small toggle switch in it.  The toggle switch shorts across the Micro-switch and allows me to run the pumps when needed, even if the lever doesn't fire the Micro-switch.  It has allowed me to finish several jobs without tearing down the box in the middle of the day.  I have also used it to run the pumps for 30 seconds or so when the weather is downright cold to circulate the oil and warm it up a little. 

I have not had any problems with the setup for several years, so now that I said that, I should check out my supplies and make certain I have spares for everything. I do have over 5200 hours on the machine, so everything has gotten broken in by now.
2001 LT40HDD42RA with lubemizer, debarker, laser, accuset. Retired, but building a new shop and home in Missouri.

MartyParsons

Hello,
Everytime I work on a remote mill I put the bolts in reverse or the nuts on the outside of the micro switch. Might help in the future.
M
"A pessimist sees difficulty in every opportunity; an optimist sees opportunity in every difficulty." -Winston Churchill

Freedom6178

Not sure if this would help but I'd put a small lock washer behind those little bolts to keep em from loosening up..
------Freedom6178------


Prepare for the unknown by studying how others in the past have coped with the unforeseeable and the unpredictable.
George S. Patton


'12 Mustang, '03 F-250 SD 4x4, Stihl Farm Boss 18"bar, '09 Arctic Cat 550 TRV EFI

Bandmill Bandit

I have not had to take mine apart yet but i did have to tighten the clamps rocker set screw.
I am wondering if it would be possible to JB weld those little nuts in place WITHOUT JB welding the the screws in at the same time. I have done that in similar situations with effective results but the nuts were visible. May be worth a shot.   
Skilled Master Sawyer. "Skilled labour don't come cheap. Cheap labour dont come skilled!
2018 F150 FX4, Husqvarna 340, 2 Logright 36 inch cant hooks and a bunch of stuff I built myself

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