Difficulty reconnecting hydraulic lines on backhoe on MT125 Tractor.

[mslisaj]

My LS MT125 is brand new with 28 hours on it. When I first got the tractor I practiced removing the loader and the back hoe and the hydraulic lines disconnected and reconnected with out any difficulty. Well I removed the hoe and parked it for about two months inside while I used the tractor to push snow. Well today I wanted to put the hoe back on the tractor and I could not reconnect the hoses. Apparently there was built up pressure in the backhoe and I could not push the couplings together. I did cycle all the controls but it finally required brute force to get this lines reconnected. Of course my tractor was not running when I was doing this but this was weird as I had reconnected these hoses before with out any difficulty. I think it was from letting the hoe sit for an extended period of time but why would the hoses be difficult to reconnect? What caused the pressure build up in the hoe section? The weather has been really cold here so there wasn't an issue with heat causing an expansion of the fluid or anything like that. Just was curious if others have experience this and how you deal with it.

Thanks for your feedback and advice.

Lisa

 

[flingwing1969]

Do you have flat face connectors or ag style connectors?

 

[Concordriver]

If the tractor had been running for a while before you tried reconnecting the lines, the hydraulic fluid was probably warm and the pressure in the system was high. Bleed down the system by lowering the front end loader, let the tractor cool down for an hour or two. Then, you should be able to easily reconnect the back hoe lines.

 

[LS Tractor Owner]

My thought makes me think that maybe the backhoe was not bleed down when it was disconnected. Meaning during the process of taking it off, you are using the hoe / stabilizers to lift it off while hydraulic lines are still connected. Before disconnecting the hoe, maybe there was still some pressure in the system...don't know, just a thought.

 

[Rock Crawler]

Before disconnecting the hydraulic lines, shut the machine off and stroke the levers in a circle. Then disconnect the lines, start the engine and pull away.

Before reconnecting the lines, back the tractor up to the hoe, shut it off, and stroke the loader lever in a couple circles to let the pressure go. Then reconnect to your backhoe. Start the machine and do your installation.

 

[jdom84]

this is pretty normal with all hydraulics and usually happens when you leave the BH disconnected for a long period of time. Even if you put the BH in the resting/locking position it can still happen because anytime you have a hydraulic cylinder with an extended rod, that rod displaces more fluid volume then there is room for when it bleeds down. In this case the bucket and dipper cylinders are extended and causing the pressure and they don't have locks, unless you know exactly where to position the dipper and bucket... it will happen every time.

Its no big deal to fix. you can loosen the fittings with wrenches and let the pressure out or you can just push the male fitting against a hard surface until it releases the pressure.

 

[mslisaj]

Thank you all gentlemen for taking your time to weigh in on my questions. First off, forgive me but I am really new to all this and this is my first "tractor". On the question of the connections being "flat face or Ag style" well I don't know the difference. They look like a simple air hose connection where one fits into the other.
I did figure I had pressure built up in the system and I'm sure it wasn't in the tractor as it had only been running for abotu 5 minutes and was cold. I did push in on the little pins on the male side of the hoses to release any pressure and also I cycled the controls. Obviously this did something as I was able to connect the lines and off I went. It just seemed odd to me as I have had this hoe off before and never had trouble reconnecting the lines. But I was just curious as to why this would happen.
On how I stored the hoe, well it was in a totally folded up condition on a little cart I built. The stabilizers were strapped up and the boom was locked. The bucked had bled down a few inches in the 8 weeks this hoe was off the tractor. So maybe that was what was happening. The good news is I got it all back together and working and I will remember all your advice here if it happens again.

I appreciate the help thank you.

Lisa

 

[flingwing1969]

On the question of the connections being "flat face or Ag style" well I don't know the difference. They look like a simple air hose connection where one fits into the other.

For future reference, the first photo is of flat face connectors and the second is for Ag style. The reason I asked is that using a piece of board one can tap the end of a male AG style connector and release a small bit of built up pressure in the system that may have developed from temperature or other conditions, one cannot do the same thing with the flat face style and they seem more prone to this condition.





Because backhoe cylinders tend to leak down over time anyway, it is probably more likely that you forgot to bleed off tractor pressure when you shut the machine off to make the hookup, as mentioned by others. As also mentioned, if you do get pressure build up and cannot connect in spite of relieving pressure in the system - happens every time I go to hook up my 4n1 bucket no matter what I do, you will simply have to crack the line connection on the offending hose to bleed off pressure.

 

[mslisaj]

this is pretty normal with all hydraulics and usually happens when you leave the BH disconnected for a long period of time. Even if you put the BH in the resting/locking position it can still happen because anytime you have a hydraulic cylinder with an extended rod, that rod displaces more fluid volume then there is room for when it bleeds down. In this case the bucket and dipper cylinders are extended and causing the pressure and they don't have locks, unless you know exactly where to position the dipper and bucket... it will happen every time.
Its no big deal to fix. you can loosen the fittings with wrenches and let the pressure out or you can just push the male fitting against a hard surface until it releases the pressure.

Thanks jdom84 for the explaination. I believe you nailed it here. The dipper rests on a stop when it's folded so it can't move and everything else was locked. But the bucket, as you said in a folded position the cylinder was extended and when it relaxed it pressurized the system. Your "fix" I just figured out with a rag over the fitting and striking the end with a rubber hammer to release the pressure. Now I know what is going on and why. Thanks again for the explaination.

Regards,

Lisa