power beyond hydraulics

[renogang]

I would like to add an additional spool valve block to my 1982 350C. I think my crawler had a backhoe at one time, and I’m trying to figure out the power beyond hookup off the original spool valve for the bucket. On the side of the aux block there is a large hose coming off the bottom that loops back around to the return to the tank, is that the pressure side of the power beyond? The part that confuses me is if that is it, with it looping back to the tank, how come that wouldnt loose all my hydraulic pressure rendering the whole system useless? The original hydraulics work fine in this configuration by the prior owner?

Im trying to post a picture link of it, could somebody let me know if it works? The port/hose im asking about I marked with the zip tie in the pic.

https://live.staticflickr.com/65535/513 ... a231_m.jpg

[JWB Contracting]

The power beyond fitting which screws into the valve shuts of the normal return flow back to the tank ( thru the valve) and sends it beyond the valve and which then must be returned to the tank.

This way you can plumb another valve in line, such as the valve bank on a backhoe. The external return must remain or you will hear a whining / screeching noise followed by a pump explosion.

[renogang]

Hey Jason thanks for the reply, I got the parts from you installed so my aux valve can run my 3 point. But then I decided it would be nice to have a 3 point log grapple attachment which would necessitate another spool valve block.

So from your reply it sounds like if I take that power beyond line to a new spool valve and then put the return from the new valve back to the tank, that should work? Is there different types of spool valve blocks that allow flow through them back to the tank so the pump isnt dead headed or are they all built that way? Just want to purchase the right type.

By the way does that picture link work?

Thanks, Randy

[renogang]

After digging for info on the internet, it looks like a open center spool valve is the type that constantly allows pump discharge to flow to the return tank, correct?

[Stan Disbrow]

Hi,

Yes. Open Center on the crawlers. The Ag machines sometimes have Closed Center. They have a different pump which works with Closed Center. The idea was to not use engine power better used by the PTO for just circulating hydraulic oil. That is not an issue with crawlers so always Open Center for us.

Stan

[renogang]

Thanks for the help guys, that clears things up. Now i just have to figure out the plumbing to my new valve block, that power beyond fitting is huge, approximately 1.25 or 1.5 inch. Prior owner used pipe fittings to make the loop back to the tank when removing the backhoe, i would like the piece of mind of all hydraulic fittings. Also need to find a place to mount the new valve block.

Thanks again, Randy

[JWB Contracting]

Another option is to add a valve segment and additional control handle vs another valve. You could also use a diverter valve on your valves third function. You don’t need big flow for the grapple or 3 point hitch.

I would stick with large sized plumbing as you have a loader machine and the higher volume pump. If you add a valve segment you can remove the power beyond fitting from your valve and the looped around piping.

[renogang]

how come the power beyond fitting is so large compared to the inlet of the valve block(discharge if the pump), i would think they would be the same size since the inlet would be the limiting factor for flow?