Loader Control Problem

[RDrancher]

The un-curl function on my TC35D started acting up yesterday and by this afternoon it was pretty much gone.

If I lay the bucket flat on the ground and try to backdrag or push, the bucket starts to curl by itself. If I stand the cutting edge straight up and down and push down on the loader arm, it doesn't have enough power to hold the position. I think that it's something in the valve, since it now has a float position past the normal un-curl position. I talked to my service tech over the phone. He believes that the bolt at the bottom of the shaft has loosened up, allowing the valve to over-travel. He said that the bolt is accessible from a plug at the bottom of the valve (spool). I don't have a diagram to refer to and couldn't find it on Messick's site. A little help please??

 

[TractorTech]

It sounds like something in the spool or linkage ov the valve. The diagram you are looking for is on the TC35D parts book, under 07.15.02, 2 spool remote valve.

 

[jinman]

John, the first thing you should do is pull the plastic cowling off so you can see in there. You'll be shocked at how many pipes are attached to that dual valve. You can see the bottom, but it is very tight and very cluttered under there. Here are some photos and descriptions of your valve including a printout of the detailed parts diagram. I only included operational descriptions of the curl/dump function, none for lift arm functions.







EDIT: One more thing. If you think it might be the cylinder seals bypassing internally, curl the bucket to level on the ground and disconnect the bucket quick connects. Lift the arms and see if the bucket can be moved to the full dump position by hand. The bucket will droop a bit, but it should hold tight after moving down just a few inches. If it goes all the way to dump position, you have an internal leak in one or both cylinders.

 

[RDrancher]

Thank you.

I found the cap loose on the bottom of the valve, so I tightened it up, it kinda worked, but as soon as the bucket was curled the valve would lockup.

This morning I took the valve out (on the job...lots of fun) and then removed the cap and the piston and spring just fell out. There was also only one ball, but the other could have easily been lost while using my tailgate as a workbench. Since I wasn't sure how it went back together, I took the valve out to Glen at NH. Turns out that their shop had never had one apart, so he got out the shop manual and with three hands between the two of us, got the spring and piston behind the balls and the cylinder back in place.

I got back to the job and put it back together. Two of the fittings and flares were a little rusty (the source of a longtime, annoying hyd. weep I'm sure) so I used emery cloth to clean them up. One of the lines I cleaned up was still weeping a bit, so I'll work on that in the morning. I checked out the operation and noticed that I don't have much un-curl power, but I think that may be air still in the lines....I hope!

BTW...this was all going on today while fourteen bellydump loads of road base were being delivered for my customer's new road. Tomorrow's going to be a busy day!

 

[RDrancher]

EDIT: One more thing. If you think it might be the cylinder seals bypassing internally, curl the bucket to level on the ground and disconnect the bucket quick connects. Lift the arms and see if the bucket can be moved to the full dump position by hand. The bucket will droop a bit, but it should hold tight after moving down just a few inches. If it goes all the way to dump position, you have an internal leak in one or both cylinders.

I'll have to try that in the morning Jim. Glen told me to curl the bucket and hold it for 15 seconds then check each of the cylinders for excessive heat. Both of them are REALLY hot when I use his method. Today the valve was working fine (no excessive travel), but the same problem with the inability to back drag out of a pile. The bucket just rolls over the top, even when holding the joystick in bypass. It really made it a pain to flick material in the corners when transitioning from one pile to the next. Still got ten loads done though, so the day wasn't lost.

 

[jinman]

Those cylinders may be around 185 F or more in this heat, especially if the loader cylinders are leaking and the fluid is circulating rather than just in-out of the cylinders. I like to use my non-contact IR thermometer to get accurate readings. Anything hotter than about 150 F is gonna feel very hot to your hand. I've measured my reservoir at 185 F when working the tractor hard in this type of heat. The HST heats up pretty good even with the cooler out front, especially if you work it hard and the HST is in bypass a lot.

 

[RDrancher]

Well...today was sure hot enough! I'll try your cylinder test tomorrow and let you know how it goes. As always, thanks for the help!

 

[KWentling]

It sounds to me like your valve does have a third position that's called "quick dump" or something similar. It combines the flow that is exhausted from the cylinders when dumping to the pressure side to help prevent cavatation of the cylinders. If you try to back drag with the lever in that position it will not hold position. If your cylinders are cavating when dumping and then trying to back drag, the cylinders will have air in them, and they won't hold position in the regular dump position either. After you dump a load, put the bucket on the ground to back drag and push the lever as if you are dumping until the bucket lifts the front of the tractor, thus pushing the air out of the cylinders. Make sure you only push the lever to the first dump position when you do this. If that cures the problem, then air being pulled into the cylinders when dumping is the problem. Running the tractor at a higher RPM (pump producing more GPM) will help to an extent. My little BX22 does the same thing.

Kim

 

[RDrancher]

I understand what you're saying about a "quick dump" position, but that's not it. I can hold the joystick in position as long as I care to and it won't build pressure. with the bucket flat on the ground, I get zero un-curl. With the loader fully raised with the bucket curled all the way, it doesn't even have enough juice to un-curl the bucket at all. It just sounds like it immediately goes into bypass. Dumping is also very slow. When grading, I'm pretty much at 2300-2500 rpm all day for hydro power and hydraulic speed. In this case, rpm does nothing to change the problem.

 

[oldnslo]

Can you install a gauge in the curl or uncurl hose to see if you are getting any pressure at that point. If it sounds like you are going over relief it would point towards the flow path is being restricted or blocked in the curl / tilt function.