Stabilizer Leak Down Cured Nardi 220

[3RRL]

After making the feet taller for my Nardi 220 backhoe in this thread Taller Backhoe Feet, I needed to fix the "leak down" problem with the stabilizers. I was guessing (and hoping) the problem was in the valve and not in the hydraulic cylinders themselves. During backhoe operation, the stabilizer legs bleed down and I am constantly re-setting them.
This is annoying...

To fix the problem, I bought two DPOCV's (double pilot operated check valves) from Mark Carter at CCM. They sell hydraulic top and side links for their Top-N-Tilt systems with double pilot operated check valves (DPOCV). Their DPOCV's are small compared to the ones I bought from Surplus Center for my side links... about 1/4th the size in fact. Problem is they are Metric. But then so are my hydraulic cylinders on the backhoe.
Here's some of the stuff I needed to start this project.

Cylinders, misc fittings and Banjo end hoses.



CCM's double pilot operated check valves.



Banjo Bolts and copper washers.



Rob-

[3RRL]

Here's my plan.
I want to mount the DPOCV's with hard lines to the cylinders.
Ultimately, something like this set up.



That means
I have to make the cylinder ports which are 1/4 British parallel thread, BSPP into 1/4 NPT.
The female end of the elbow will be a 1/4" NPT to fit one end of the hard lines (tubes) I will make.
The other end of the tube will need to be 12mm diameter. Reason is because the DPOCV's have a 12mm compression fitting. No one has tube in stock and the minimum you have to order is a 20' length, so I'm making my own out of tubing stock I have for my plastic injection molds.

OK, now the tube will have a 12mm OD on one end that will fit into the compression fitting of the check valve and the other end will screw into the 1/4 NPT port fitting elbow. The reason for a compression fitting is so you can assemble the whole thing with the 12mm tube inside the check valve and screw in the 1/4NPT into the port fitting elbow. Wherever it screws to, it will leave some tube inside the check valve and you tighten the compression fitting at that point.

After that, I plan on reusing the hoses, which have the banjo fittings and bolts. But they are the 3/8 BSPP ones. They also have a 90° metric JIC on the other end to fit the valve spool, so I'm going to re-use them instead of trying to get them made up. That would take forever!

Now for the last fitting needed. The outlet and inlet on the DPOCV is 3/8BSP taper of all things! So I got a 3/8BSP male bushing to thread into the check valve with a 1/4BSPP female. Then I can bolt the old hoses on with the old 3/8BSPP banjo bolts and be done with it.

As shown above, this how I'd like to have the check valve sit on the cylinder.



Rob-`

[3RRL]

Here's an update if anyone is interested.
I started trying to make the hydraulic tube that goes from the cylinder elbows to the DPOCV. This required making a 1/4 NPT thread on on side and a Ø.480" on the other to fit inside the 12mm metric compression ring.
I used 303 SS hex stock, turned one side and used a 1/4NPT die to put the threads on. Then flipped it around to turn and drill through.
This is how they turned out with the compression sleeve on them now.



With the tubes machined, I was able to put the hard plumbing and check valve on the cylinders. I must say they came out excellent ... even if I say so myself. In order to do that, I measured the distance between the elbows on each cylinder (they were different by .100") so I could cut the 303SS tubes to length. They need to slip between the elbows while set deeply into the DPOCV's.

Then I bought some pipe seal hex nuts and put them over the NPT threads of the SS tube.



I did this as a safety measure so I can get a positive seal, but mostly because I did not want to screw them into the elbows too far. Otherwise the compression end might come out of the DPOCV. I measured how much I could slip them out and still have enough to make a good compression seal. Then screwed them into the elbows while measuring to maintain that safety margin. Fortunately, there was enough travel to screw them in almost completely tight anyway. Then tightened up the elbow ends.

Last, I had to center the DPOCV on each cylinder so that the compression ends were of equal engagement and tightened that end up. Now the hard lines with DPOCV are complete. Aren't they beautiful now? I think it is a super clean bridge.



Rob-

[3RRL]

Now I can take them up to the property to install. But before hooking the hydraulics up, I am still waiting for a fitting from Discount Hydraulics. Their overnight delivery takes several weeks I found out. This reducer sleeve goes into the 3/8 port of the DPOCV's. I bought 2 kinds because at the time I wasn't sure what the thread was inside the check valve. It turned out to be 3/8 BSP male (taper) to 1/4 BSS (straight (parallel) female).



I will tell you what difference the DPOCV's make on the stabilizers after trying them out. I'm hoping they will work a lot better than the fast bleed down I had before. In other words, I'm hoping the bleed down is because of the valve and not through the cylinders themselves. This modification will tell me for sure.
Rob-

[3RRL]

Back at camp, here is the cylinder mounted back on the stabilizer legs.
Notice how nicely the check valves fit in there.
Everything clears too when folded up.



I finally got the fittings I've been waiting for. It only took Discount Hydraulics two weeks to send them next day air.



The difference between the BSPT and NPT is not just a few thousands in diameter, but more so one thread per inch. Now that I got them, I was able to see which fits, and found out it was the 3/8 BSP. I can start working the backhoe again and check out the new red shoes too. Not only will they be taller and offer more stability for Huge Kama, but the backhoe legs should not leak down anymore. I'm hoping to use the backhoe and company to dig the footings for the foundation of the water storage tank.

Rob-

[3RRL]

I got the fittings installed and re-connected the hydraulic lines. Then mounted the hoe to the tractor for a tryout.

Here are some photos of how the DPOCV mounting worked out.



The hoses fit perfectly and did not get squished.



I zip tied them together to keep them in position, but when screwed in and fastened, the hoses didn't move anyway.



The fittings sealed perfectly and so did the BSPP (parallel) threads for the banjo bolts. They did not leak a drop.
Rob-

[3RRL]

In testing them out and also the new feet, I found them plenty wide enough and they grabbed the ground solidly. A couple photos after getting the hoe on.



This shows how neatly the hydraulic hoses are routed with the check valves on the cylinders.



I know now those check valves work good.
I dug a 4' x 4' x 4' hole as a test with no leak down at all. Took about 30 minutes to do that in my hard ground. The feet held up with no hint of buckling at all. Then I dug a 10' diameter about 4" deep for my water tank, but that was on all decomposed granite and it was as hard as rock. It was baked and I spent at least an hour and a half screwing around with that. So I settled for 4 " and put a steel ring up tp form the concrete base. No problems there either.

I think the feet and the DPOCV's modifications are a definite plus, making it worthwhile to get a more stable and safe operating backhoe. Not only that, but after nearly 3 months of sitting in my tractor tent, the legs NEVER bled down. I was able to dive the Kama up to the hoe and hook it up without having to plug in the pump to reposition. It was great.
Thanks for looking.
Rob-

[affordable]

Rob,you have a backhoe with high heels on now,looking good

Tommy
Affordable Tractor Sales

[3RRL]

affordable said:

Rob,you have a backhoe with high heels on now,looking good

Tommy
Affordable Tractor Sales

Hahaha,
It's an Italian backhoe so why not Stiletto pumps, right?

[baknblack]

Rob,
I wish I knew 1/100th of what you know about machining, thread sizes, etc, etc, etc, lol.

All those different threads and connections for piping and hydraulics just confuse the crap outta me. I can match stuff up if it's in front of me but, I never know what to order when trying to order off the internet.


Did discount hydraulics refund the extra shipping?

[3RRL]

Thanks Dwayne,
Just stuff I picked up over the years in the machining industry....a necessary evil, like heat treat!

Did discount hydraulics refund the extra shipping?

Yes, but those pricks did not tell me they don't have (or keep?) the metric adapter bushing in stock. They had to order them and them and didn't tell me. I got their email saying "your order has been shipped" about 2 weeks after I placed it. I said WTF??? is up with that? So I called them and said you know that was an "Overnight" request don't you...as in I need it yesterday. And you guys didn't bother to tell me the situation? They said they were sorry.
The next order was the same except I knew to ask if they had the items in stock or not, (and not, of course) so I was prepared.
I would much rather buy from Surplus Center, but they don't carry the metric conversion bushings. They have everything else though and are pretty reasonable. Plus, I like their on-line catalog and they usually have a "spec" sheet with dimensions etc., so I can design within.

Hydraulic hoses though, if you can use standard 4,000psi two or four wire ones with NPT male ends (1 fixed, 1 swivel) are the best bargain at Agri-Supply. I've even ordered twice as long and cut them in half then have my hydraulic guy put an end on cheaper than he could make the whole (two hose) for me. Sometimes, if the valve or cylinder needs a JIC or ORB fitting, it's still cheaper to buy that adapter (JIC or ORB to NPT) at Surplus Center and add to the Agri-Supply hose. Having hoses made custom can add up quickly, like 40 or 50 bucks a hose easily.
Rob-