Frozen Chain Trencher

Digger 258 · Mar 14, 2016

I bought my used PT-425 back in November along with a trencher. Clearly the trencher had been sitting outside for years unused, as it had a bit of rust on it. trencher didn't look heavily used before it was parked outside, as the teeth weren't beat up or bent.

This weekend I decided it was time to start on the thousands of feet of trench I have to dig for drainage. Hooked up the trencher, flipped the PTO switch and . . . nothing. Trencher is frozen.

I sprayed everything very liberally with spray lube and beat on the thing with a heavy plastic dead blow and tried again - just a slight jerk when I flip the PTO on, and nothing else.

Sprayed some more, waited 24 hours, loosened the tensioner up all the way. Still no spin of the trencher. Right now I have it sprayed in more lube. I'm thinking I might need to take the chain off of the trencher and beat every link with a hammer to work some movement and then reinstall.

Surely some of you have a trick I haven't tried yet. Any thoughts?

woodlandfarms · Mar 14, 2016

It sounds more Hydraulic. would be surprised if it is the chain (the forrce of the motor should break it free, I mean the thing is breaking up rocks and everything).

Does the engine bog down when you turn on the PTO? If it doesn then I would remove the chain to make sure the motor is turning. If it does not bog down then you got a bad motor that is bypassing or....

Digger 258 · Mar 14, 2016

The engine bogs down when I turn on the PTO, and the chain bumps (like it's trying to move) a couple of millimeters or so, and freezes. Engine definitely changes it's tune when I put the PTO on - it doesn't die out or anything. I assumed the hydraulic motor on the trencher bypassed fluid if it was so rusted as to not be able to turn it. I guess I'll try to remove the chain and see if I have a spinning motor . . .

woodlandfarms · Mar 14, 2016

The motor could be worn out. you never know on these things. Front sprocket could be frozen.

Heat and wax is a VERY good way to get in as long as there are no plastic or bearing oriented parts. heat the heck out of it, and then push a white candle into the gap, wax melts and gets into the rusted parts.

Marks481 · Mar 14, 2016

Sure you don't have a stone caught in the teeth somewhere you can't see? Every now and then I get one lodged in really good and everything stops until I break it up with a chisel.

MossRoad · Mar 14, 2016

Yeah, I was thinking maybe a rock is binding it somewhere.

As others have mentioned, look for obstructions.
IF no obvious obstructions, then try removing the motor (or chain) and seeing if the PT can spin the motor with no load.
IF motor doesn't spin, motor problem.
IF motor spins, chain or track or sprocket problem.
Start at the beginning and move along down the line until you find the issue..

I love IF, THEN troubleshooting. :laughing:

Digger 258 · Mar 14, 2016

I got out of work too late to do anything tonight, but I'll look for rocks and obstructions. I would have thought I would see one while I was lubing every link in the chain, but was not specifically looking for that - even though that's probably what I should have looked for first! I'll also try the candle wax idea, (that sounds like it could be fun). If no joy there, I'll try taking the chain off or the motor off, whichever seems easier . . . Probably be Thursday before I can get to it but I'll let you know what I find. Thanks for all of your help so far. I've put 50 hours on the PT since November, and if it weren't for that pesky job getting in the way, I'd surely put more. It's just so darned convenient . . .I had no idea what I was missing before the PT.

BobRip · Mar 15, 2016

Sometimes the chain will jam on one of the sprocket teeth. You can tap the chain with a hammer and clear the jam. I always carry a hammer and cold chisel when using the trencher. Rocks get caught in the sprocket and chain interface. Chisel and hammer will clear this.

johara1 · Mar 17, 2016

Why can't you run it back wards, if something caught it will free up….. jim

Digger 258 · Mar 17, 2016

I thought about that, but in my novice mind the only way to do so would be to switch the hoses at the motor, and I guess I am not sure if running the motor backwards will hurt the motor at all. Does switching the hoses pose a serious risk of contamination of the hydraulics with dirt or introducing air that would hurt anything? I'll take any ideas . . . Hope to get working on it tonight, and if not I've got Saturday. I'll let you know what progress I make.

ultrarunner · Mar 17, 2016

Left my dozer sit the time I was working overseas and the tracks were really bound up.

Used the blade and ripper to get the tracks off the ground and was able to free it up... after that... no matter what I ran the tracks every other month.

I can see the chain seizing on a trencher... maybe PB blaster and warming things up with a torch... not so hot as to affect temper or hardness.

Had some chain saw chain what was given to me... rusted... let it soak in Diesel and it freed up enough to use it.

Can you whack the joints with a 5lb hammer and a brass drift or hardwood... just a whack at each joint on both sides?

MossRoad · Mar 17, 2016

Digger 258 said:
I thought about that, but in my novice mind the only way to do so would be to switch the hoses at the motor, and I guess I am not sure if running the motor backwards will hurt the motor at all. Does switching the hoses pose a serious risk of contamination of the hydraulics with dirt or introducing air that would hurt anything? I'll take any ideas . . . Hope to get working on it tonight, and if not I've got Saturday. I'll let you know what progress I make.

I don't know if that motor is reversible or not.

If it is, you could reverse the hoses and run it backwards. I'm not familiar with the PT trencher. I don't know if it has a tensioner or not. If so, that might be a concern for running backwards. A little air in that circuit won't hurt anything. Its the tram circuit you don't want any air in ever. As for dirt contamination, YES! That's a serious concern on all hydraulics. Clean the areas really well before cracking any fittings open and don't leave them open for extended periods of time.

ponytug · Mar 18, 2016

I asked Terry about this, and he said don't do it. Not all hydraulic motors run backwards well, and supposedly the chain trencher motor is one of them. (At least on the 1445.)

For stuck rocks, I have found that turning the PTO off, placing the trencher on hard ground and backing up has always freed the rocks in a few seconds.

X2 on the advice to see if the motor turns by itself before you do much more.

All the best,

Peter

MossRoad · Mar 18, 2016

I think dragging against rotation with the PTO off is also the preferred method to clear rocks on PTs tiller as well.

BobRip · Mar 18, 2016

If you plug the hoses together this will allow a little backflow when you back pull the trencher

Digger 258 · Mar 18, 2016

Thanks so much for the help and advice to everyone. I came home from work with just a little daylight left and set to work. I examined each link and tooth on the sprocket very closely for rocks and obstructions, and I loosened up the tensioner again. Then I cleared space in my garage so I can work late into night to take it apart piece by piece. Pulled her into the garage and started getting tools ready. Decided that I might as well try the PTO "one more time" before I started taking the motor off. I flipped the PTO switch, and lo and behold, after a slight pause, a mighty racket let forth and the trencher was spinning! I tightened up the tensioners and tried it again. It spun just fine and I soaked it in lube while it was running. I suppose patience is what I needed to let the lube set in - I never even got the chance to try melting candle wax into the links. Anybody know how to set the tension right on the chain? I am excited to dig trenches now, even though it's supposed to snow Sunday . . .

ultrarunner · Mar 19, 2016

Good Deal... sounded just like when I let the dozer sit too long.

One of my contractor friends never lets equipment sit outside without running it every couple of weeks.

BobRip · Mar 19, 2016

To set tension- put the chain horizontal and off the ground. Adjust the distance between the center of the lower chain and the bar above so it is the width of your fist. Got that from Terry many years ago.

Digger 258 · Mar 19, 2016

Thanks BobRip - that's an adjustment that even I can follow. Once I get that done I can trench my way to our Northern VA PT owners meeting! Once I get trenching I'm sure I'll create some other crisis . . . First time ever trying French drains.