Go BottomBanjo Hydraulic fittings question
 | tomrscott
Join Date: Dec 2004 Posts: 96 Newberg, Oregon 
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2005-01-12 104052
I found a real good online catalog with a lot of application data about all types of hydraulic fittings:
http://hydraulics.eaton.com/products/pdfs/W-HYOV-MC001-E_application_data.pdf
It's the Weatherhead company, recently acquired by Eaton. They seem to be a bit supplier of this stuff.
Anyway, I was looking for a reference to banjo fittings. But with all the stuff this place has, they didn't have anything that helped. The SCV on my JD790 uses those at all the ports. I am not finding these connectors in any of the usual places.
I found a British company that had British threaded banjos that then convert to a tubing coupling.
http://www.indanc.com/steel-compression-fittings-06.htm
I noticed that they say the male thread that compresses the banjo part, is available as a BSPP or metric thread.
But that begs the question, what is the thread on the JD banjo going to be? Is it going to be metric? Or does JD/Yanmar use American standards for those things?
Is it possible that some other male threaded fitting, not necessarily a banjo can be screwed into the port that they've connected a banjo to? The tubing that is connected with the JD banjo appears to be 3/8" with 0.485" OD. The hex head on top of the banjo is approximately 1.07", didn't have a socket set handy to try and see what fit. The banjo ring that is clamped by the "bolt" is about 0.7" thick. I don't really want to take these things apart until I am ready to re-do it. I suspect they could be real tight, and the quarters are cramped. I need to tap into the hydraulics PB at the FEL SCV and then return to the rockshaft P port.
I am just wondering if the port this banjo is screwed into is actually a 1/2" NPTF or something that I can put a standard 90 ell with a compression coupling on the other side?
Maybe I don't need to find a banjo?
Anybody know what these threads are, or a source for the correct banjo fittings? I'd like to run tubing for the power lines to the TNT, but may settle for hoses, but I have to figure out how to connect to those.
Thanks!
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Add PhotoBanjo Hydraulic fittings question
| tomrscott
Join Date: Dec 2004 Posts: 96 Newberg, Oregon
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2005-01-23 104745
Just to follow up in case someone else is interested. I finally decided the only way to be sure about the correct thread was to buy one of the banjo bolts from JD and measure it. I could have just taken one out of my tractor, but then I'd be into the job and didn't want to dump the trans/hydr fluid and all until I had the parts to plumb up the new TNT installation.
It turns out, as I was guessing, that the banjo bolts are the same thread as an SAE8, 3/4" x 16 TPI. An appropriate replacement is an SAE8 straight thread O-ring fitting. I verified this with a high quality thread gauge and by threading an SAE8 threaded cap onto it. I thought there was some chance that this could be a BSPP thread, but the thread gauge confirmed that it is an Amarican thread, the BSPP threads have a slightly different tooth angle that is distinctly visible with a thread gauge.
The other odd thing in the hydraulic plumbing in the 790 is the steel tubing pressure lines from the pump to the SCV valve and from the SCV to the FEL couplings. The tubing measures .485" OD. Normally hydraulic tubing is measured in even OD sizes, 1/4" 5/16", 3/8", 7/16", or 1/2". This makes it 0.015" shy of 1/2" even with a coat. It is also not quite a metric size, about 0.012" smaller than 12mm. Seems odd, can't understand what this size is? It turns out that the return to tank line that I want to tee into will be pretty awkward to replace with other fittings. I was kind of planning to just cut this line open and put a compression tee in the middle of it for the new tank return line, but I don't think a 1/2" compression fitting will squeeze down enough to bite into tubing this small.
Other options:
1) Make some custom brazed TEEs with the .485" braze slip fittings on the ends and maybe a standard SAE8 port in the middle?
2) Replace the line I need to tee into with a new 1/2" line with SAE8 all around. This is fine in theory, but both ends of this line are in a pretty awkward locations for spinning on SAE8 ells. One virtue of the banjo fitting is that it takes almost no clearance to spin the banjo bolt in with the banjo tubing oriented any direction needed. All you need is enough clearance for a box wrench. With an ell fitting you have to have about 1" clearance around the port for a full 360 degrees to thread the ell into the port.
3) I suppose I might be able to cut the existing line open, put 37 degree flares on the .485" tubing ends, and use a JIC tee for 1/2" tubing?
Something to comtemplate some more. ....
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