Lock valves on 400x loader

The type of valves are called "Double Pilot Operated Check Valves" or DPOCV's for short. They are usually attached directly to a cylinder and hard-piped. Here is one style at the Surplus Center: http://www.surpluscenter.com/item.asp?item=9-5606-50&catname=hydraulic
You can look at this TL cylinder to get an idea of how they are usually plumbed: http://www.surpluscenter.com/item.asp?item=9-7682-08&catname=hydraulic or this (mine):

The small ones used on the cylinders cannot be found for sale in the US by themselves, and the ones at the SC are kind of big and have large ports hat would need to be adapted taking up more room. Since you have two cylinders, you could put just one valve inline to stop the leakdown, but of course that will not protect against a hose blowing after the valve.

If you put one on the the Lift/Lower circuit, you would loose the ability to "float" the loader.

Clear as mud?

PS: I moved this to the hydraulic forum since it seams better suited there.

OK, thanks for the mini lesson on valves.


I'm learning a lot from the group here.
I appreciate it.


I just ordered a top link from the surplus center,
from suggestions posted here.

(4720, 400x loader)

Kenny would know much more about this, but this is the little that I think I have understood.

These vales take around 600 psi to open them, so if you put a little pressure on them, they do not move. You do not have to bump them with full pressure, but close to it to get them to move. They can be moved in small increments, but its jerky, not smooth as the valve is opening and closeing since you are not giving it enough pressure to keep the valve open. So it jerks open and it move 3/8 to 1/2 inch.

You guys got it right, there is the possibility you will sacrifice smoothness with the DPOCV.

This is copied directly from the Surplus Center page:

Pilot-operated lock valves may chatter when used in cylinder circuits with heavy loads. A restricting orifice can be plumbed into the hydraulic line to reduce this problem.

Click to expand...

I do not have this problem on my machine, but I am only flowing about 5 GPM and I also have 1/4" hoses going to the HTL to help restrict flow.

There unfortunate is no free lunch here.

@Brian: What size hoses feed your HTL?

@DS: I suspect you will be fine if since your flow is lower like mine, just use 1/4" hoses.

@stone7: If you have not figured it out, I would suggest 1/4" hoses for your HTL as well:thumbup1gif:

What are you doing with your forks that the leakdown is causing a problem for you?

@stone7: If you have not figured it out, I would suggest 1/4" hoses for your HTL as well:thumbup1gif:

What are you doing with your forks that the leakdown is causing a problem for you?

Click to expand...

I work on my mower deck(JD445), and I'd like to turn the tractor off
for noise and exhaust.

And I'm building some slip-on metal plates,
to go under the tires of the 445 to lift the whole thing up for MX stuff.
(I'll post pictures, when finished)
(I'm talking about lifting things to work on, with the 400x loader, and the fork attachment)

I use the loader and the forks for a lot of stuff. I put a pallet on the forks, and the work item
on the pallet, and it's a heavy lift work bench of sorts.

As far as the hyd top link hoses, I'm still stumbling through this. But I thought I
would be able to find hoses at tractor supply or similar. I'd like to use elbows on the
cylinder to point aft, and then route the hoses upward in a single 180 arc into the
hyd couplers. I was thinking I could probably find some inexpensive premade hoses
that would probably be too long, and then cut them to fit, and use a reusable fitting on one end.

I don't know much about hydraulics, I'm a little spooked by the high pressure pin hole leak
issue. It would probably hit me right in the back of the head...

Stone, forget the pre-made hoses from TSC, the ones they have are low quality. Once you cylinder is mounted, you can figure the length's you need and the proper fittings, then just go to a local hydraulics shop and get the right stuff. You will be happy and supporting the local guy is always nice as well.

Start a new thread when you get it and we'll walk you through.

Kennyd said:

You guys got it right, there is the possibility you will sacrifice smoothness with the DPOCV.

This is copied directly from the Surplus Center page:


I do not have this problem on my machine, but I am only flowing about 5 GPM and I also have 1/4" hoses going to the HTL to help restrict flow.

There unfortunate is no free lunch here.

@Brian: What size hoses feed your HTL?

Click to expand...

I would have to look. They might be 3/8. I purchased them from CnC when I bought the top link. They just asked me how long I wanted them.

Mine works smooth if I have a long distance to move it, but its not as easy to move short increments like a 1/4 inch. By the time I "pop" the safety valve, it wants to jump 1/2 inch.

I put a 1/2" ball valve on the boom cylinder head end hose at the same time I swapped from 6 quick couplers to a MultiCoupler. I know this does not take the place of stands or removing the loader, but is better than relying on the spool valve to hold the loader up. I also see JD is doing this on the new H series loaders. So if it got by corporate lawyers, it can't be all bad. Valve is rated for 7250psi and has SAE 8 ports.

So what happens when the cylinder bleeds off? Would it be correct to say that
it's just a matter of 'flow' occurring?

What I'd like to know, is, do you only need the one ball valve to stop the thing
from moving?

Thanks.

If your cylinders are internally leaking you will still have leakdown. I think the ball valve is just a more positive shut off than the the loader control valve. I've used it when I've had something hanging from the loader I wanted to work on with the tractor shut off. I had no down drift. I was NOT working under the loader, or the load on the loader. As stated in my original post if you plan to work under the loader use stands or take it off.

Brian said:

But Ken, wouldn't putting those on the loader make it hard to move it in small increments as the pressure would have to break the valve open?

My HTL, like you have pictured is not smooth at all. Its jerky when it moves.

Click to expand...

My top link with a DPOCV from CCM can be moved very smoothly. It's on my lever operated factory 3rd rear SCV circuit and I've never had an issue.

-Jer.