hydraulic operations suddenly gone.

[Ghostrider 67]

I was operating my towable 9hp trencher/ backhoe to move manure from under the winter shelter that my livestock use and I shut it down to eat lunch. When I came back to it the unit suddenly has stopped operating. The controls are fine but no action. Well, almost no action, I can get the boom to move outwards very slowly and traverse very slowly but nothing else. The 9hp Predator motor runs like a top and the jack shaft to the pump is spinning. The hydro reservoir is at max full and there are no leaks. I have been using this equipment since new last summer. Love the machine, it does everything I need it do. No issues till now.
Possible problems I have come up with are:

A shear pin snapped?
Air in the system?
Dirty filter or screen somewhere?
Does it need to have each boom cylinder bled again.

I need this fixed, it's sitting right in the middle of the way, in front of my barn! lol.

Thanks in advance for the help!

Ghost.

 

[seville009]

I have no knowledge about that equipment, and am not a mechanic......so here's what I would try as a simple residential user.

(1) shut it off, and then re-start it.

(2) maybe loosen the couplings as you mention, let a little fluid dribble out, re-tighten, then start it up and try it.

(3) pull the screen or filter and see if it's blocked.

 

[Fxfymn413]

I am not clear about when it quit. Was it operating OK and then quit or did it not run properly as soon as you started it after lunch?

Are there any quick connects in the system? If so make sure they didn't come loose. Is the pump driven through a flexible connector such as a Lovejoy L-Jaw coupling? If so the coupling may have stripped internally and still has enough "grab" to drive the pump until it requires pressure build up.

 

[Ghostrider 67]

It was fine when I shut it off to go eat. When I came back it wouldn't build enough hydro pressure to move the boom. After awhile it di move, slowly. once I go it back onto more level ground it picked up speed a little and I was able to move it out of the way. The tank dipstick reads max full. the drive shaft to the pump is a sold shaft right off of the engine. I'm thinking it's a blockage issue in the spin on filter maybe. The keyway shear pin is okay. It acts like it either has air, or is blocked partially. The boom and bucket is suspended in mid air and not sinking so there is that.

 

[ericm979]

Make sure none of the valves are stuck on.

 

[KWentling]

Filter should be on the return side so I don't see that being the problem. Maybe a collapsed suction line? Does the engine labor at all when trying a function? Could we get a picture showing the engine to pump connection and plumbing?

 

[BeezFun]

Given your description, something changed suddenly. So something like a relief valve stuck open or a quick disconnect got dislodged, or some bypass valve got opened, or a detented valve is in detent position, or whatever.

It looks like the lines are hard plumbed, I would pick the easiest line going back to tank and disconnect it, then turn the engine on and see how much return flow you get. I would wild guess for that size thing you should be in the range 5-15 GPM. If it just trickles out, then you know there's a problem with flow. If you have good flow the next step would be to measure the pressure. You'd need a gauge to check that.

If your horses are anything like ours, I would guess one of them came over and messed with something while you were eating lunch. We've got a horse that pulls the tail light stalks off my tractor and rips the license plates off the trailers for fun.

 

[Ghostrider 67]

Donkeys, not horses and they are curious about everything. I will post up some closer pictures tomorrow. The owners manual is less than useless. I assembled the thing. 9 HP engine and no it doesn't lug down on load when using the thing, Just a minor change in pitch when moving the boom around and when pressure is applied. I'm a little nervous about hydraulic pressure getting loose. I saw a soldier killed once by a hydraulic hose bursting on a tracked folding bridge. Slammed closed and sandwiched him in between spans. Splat! Was NOT pretty.

 

[Fxfymn413]

In my experience it is often something simple that get overlooked because you convince yourself that it must be something major. I think the major clue here is the fact that the issue occurred when you shut down the machine or when you started the machine. I'm sure you have tried this, but just in case; go through the exact steps you took to shut down or re-start the machine to see if anything is not correct. Maybe a piece of linkage became disconnected or jammed?

The boom and bucket is suspended in mid air and not sinking so there is that.

If you operate the valve the boom should come down via gravity. Given that it is not responding I think the issue may be in the control valve for that function or possibly in the cylinder. Make sure the valve actually operates when the handle is moved; if the valve moves I think you will have to bleed the lines off that come from the boom cylinder to the valve by cracking the line that raises the boom while the machine is off. It will be messy so be ready. You can then remove the valve for service.

If that fails to resolve the issue you will need to come up with some diagnostic tools to base your diagnoses on. Is there a convenient place to put a "T" with a pressure gauge in the pressure side of the system?

 

[Ghostrider 67]

The boom does sink when the lever is operated. It just goes UP slowly. It's been hanging in mid air where I left it since yesterday and has not sunk. so, the hydraulic pressure is not escaping anywhere. Here's some pictures of the thing. I'm about convinced there's a blockage somewhere.