Top n tilt problem

[westbrooklawn]

Installed top n tilt system on my L3400 a few years ago. 3 spool valve (just use 2), and cylinders with check valves. System worked fine until a week ago... Top cylinder will retract fine, but won't extend. I switched the two hoses for that cylinder at the valve connection points, and it works fine... Switch them back and original problem returns. Ideas?

 

[s219]

Sounds like the check valve might be messed up or connected wrong. It's the only part of the system that would respond differently to flow direction.

 

[westbrooklawn]

Sounds like the check valve might be messed up or connected wrong. It's the only part of the system that would respond differently to flow direction.

S219 - Thanks for the reply. The check valve can't be connected wrong, since it has always been connected that way and has functioned perfectly. When I change the hoses at the control valve, all I am doing is changing the "source" of flow, and the piston returns to normal function. Wouldn't this indicate the check valve AND the control valve are functioning properly?

 

[s219]

I was thinking maybe the check is not allowing flow in one direction when it should.

Can you switch the top link hoses to the other spool (from side link) and see what happens? That would verify function of the spool valves at least.

 

[oldnslo]

Long shot but possible one of the quick disconnects has a weak spring on the poppet. If you feather the control or try to move the cylinder very slow does it work?

 

[westbrooklawn]

Long shot but possible one of the quick disconnects has a weak spring on the poppet. If you feather the control or try to move the cylinder very slow does it work?

No, feathering doesn't work... cylinder won't move at all, although hose flexes hard, so I know it is getting pressure.

 

[westbrooklawn]

I was thinking maybe the check is not allowing flow in one direction when it should.

Can you switch the top link hoses to the other spool (from side link) and see what happens? That would verify function of the spool valves at least.

When I get to the shop I will try switching the hoses to the other spool and see if it works.

 

[oldnslo]

Are both hoses flexing or just the one? If both then the problem is located either in the quick disconnects or your directional valve.

 

[GPintheMitten]

I had a problem that was very hard to diagnose. I thought I had correctly ruled out the quick disconnects but was wrong. I suspect quick disconnects based on your description.

It's a pain to do but consider removing the disconnects temporarily from the circuit by plumbing in a hard fittings in between. In doing this test, at least you can rule them in or out without spending much money.

 

[Roughshod]

Or instead of changing out quick disconnects for hard connectors, you could just swap on the quick disconnect ends from the unused ports, or maybe from the other working ports. Zero costs to verify the quick disconnect ports aren't blocking you.