Remote valves and hyd top link question

IndyIan · Jun 30, 2012

I've got a top link hydraulic cylinder (with check valve)on my tractor. I find though that it won't stay in position all the time, I'll tip up the box blade to use the rippers and then the cylinder will compress letting the box roll when I drop the rippers into the ground. But if I move the hyd top link while there is pressure on it, it will stay locked up indefinitely. It should operate like the front end loader right? Only move when you use the remote levers.
I've tried both remotes and they act the same. The hyd top link used to stay in position all winter when I plowed snow with a light 7' rear blade.
If the check valve failed in the top link, wouldn't the remote valves keep it from moving quickly anyways? Or can a check valved hyd cylinder still lock sometimes but allow fluid to move freely from either side of the piston other times?
I guess I should try to find a diagram of how they work...

SSdoxie · Jun 30, 2012

Sounds like you are getting cavitation in the cylinder. Are you extending the cylinder when this happens? What engine RPM are you running? The check valves only come into play after the remote lever is back in neutral, if the weight of the BB pulls the rod out faster than oil can fill the base end, you will get the spongy air pocket. Try running at higher RPM for more pump flow to the cylinder. You might need to put a one way restrictor on the rod end circuit to slow the out flow allowing the base end to fill/push with pressure.

MtnViewRanch · Jun 30, 2012

Have you tried feathering the control when you are adjusting the top link? Another guy with a JD was having a similar problem with a top link that he had purchased from me. The problem is that when you have a heavy implement hooked up and that implement is up in the air, the implement will fall faster than the fluid will go into the port, so you end up with cavitation just like SSdoxie said. You need to feather the control or get 2 restrictors. One way or another the movement of the implement needs to be slowed down so that the fluid will keep up with as fast as the piston moves.

Good luck

IndyIan · Jul 1, 2012

MtnViewRanch said:
Have you tried feathering the control when you are adjusting the top link? Another guy with a JD was having a similar problem with a top link that he had purchased from me. The problem is that when you have a heavy implement hooked up and that implement is up in the air, the implement will fall faster than the fluid will go into the port, so you end up with cavitation just like SSdoxie said. You need to feather the control or get 2 restrictors. One way or another the movement of the implement needs to be slowed down so that the fluid will keep up with as fast as the piston moves.

Good luck

Well I'll try adjusting it very slowly then, see how that goes. How does air get introduced into the cylinder or is it just pure vacuum? I guess a restrictor can go on on the line to the top link?

MtnViewRanch · Jul 1, 2012

IndyIan said:
Well I'll try adjusting it very slowly then, see how that goes. How does air get introduced into the cylinder or is it just pure vacuum? I guess a restrictor can go on on the line to the top link?

You are getting a vacuum. I sell restrictors that I install right behind the male quick connect ends. Lets hope that feathering the valve is the answer.