fluid flow

[phorton22]

I have a tlb and recently the piston broke off the ram during normal operation, nothing significant happened at the moment to cause any damage. So a couple questions about that. What would cause that? So I took the cylinder off and left the lines open (just put a towel over the inlets)and was going to move the tractor out of the shop for the time being. When I started the tractor fluid flowed out of both hoses. Is that normal? I guess I thought no fluid would move with out the joystick engaging the extend or retract.

 

[J_J]

The piston is held on to the rod by a nut. The nut loosened and came off. Check the threads and see if they are good enough for re-assembly. If so, use Loctite 542.

With the valve levers in neutral, the fluid is supposed to be blocked. You may have hose fluid leaking past a spool in the valve.

Is the valve spool returning to neutral?

 

[oldnslo]

Which cylinder broke? Depending on the valve type and application there could be some anti-cavitation check valves that connect the tank line to the work ports. If these are in this valve section fluid could flow due to back pressure in the tank line being higher that the cracking pressure of the check valves.

Or like JJ said could just be from leakage.

 

[phorton22]

The arm cylinder broke -it actually sheered and left the threads inside the piston. It seems to me that the valve is returning - I may start it again and see if it quits - it was a substantial flow out of each line, I find it hard to believe that anything could be that open, but I am no mechanic thats for sure. A pressure valve sounds reasonable but I have no idea if anything is there that would let this happen.

Anyways, about the cylinder breaking - any other thoughts on why something like this would happen, is it possible the fluid flowing by the valve and the breakage related?

 

[J_J]

Is your tractor open center or Closed center hyd system.

Fluid in an open center hyd system will not normally flow out the blocked work ports, as the fluid will normally pass freely through the valve with little or no pressure. .

A closed center hyd system might have pressure on the spools at all times and if the spools are worn, will pass fluid out the work ports.

A hyd valve in neutral, should not leak any fluid through the valve work ports.

You did not say how old anything was.

Did you check your load checks valves?

 

[phorton22]

View attachment hyda0001.pdfView attachment hydb0001.pdfView attachment hydc0001.pdf

Here are the hydraulic schematics, its the arm cylinder that broke.

I have not checked anything at this point.

Thanks!

 

[J_J]

If you are supplying fluid to the cyl and it is not moving, then I suspect the piston nut has come off .and fluid is just moving back and forth through the center hole in the piston...

 

[oldnslo]

On the tilt cylinders item 10 is a work port relief with the anti-cavitation checks. These would allow oil to flow out the work ports from tank back pressure. Schematic does not show these on the lift cylinders though.

 

[J_J]

If your lift cyl hae a QD on the work ports, just disconnect the cyl hose and see if the valve will go into relief when you select the extend or retract.

Disconnect the rod end of the cyl's from the bucket and see if you can pull the rod out of both cyl without taking the end cap off and not the piston.