question about hydraulics. Log splitter

[BotaBigot]

...
But there is a risk of at least damaging the seals on the splitter valve (and perhaps worse) if you use the three point hitch at the same time that the FEL spool is shifted, since the splitter valve has no power beyond. The pressure needed to operate the tph will also be present in the exhaust gallery of the splitter valve, and I doubt (but have not checked) if it is rated for more than 200-500 psig back pressure. You can probably get by if you return the FEL spool to neutral every time you raise the tph, but that seems like a trap for someone who is not familiar with the system.
If (and that's a big if) you are not going to use the three point hitch,

Aha! Thank you Farmer. You've addressed the one nagging concern I've had about plumbing a 3PT splitter into the BH PB circuit on my BX24...back pressure in the exhaust (tank) side of the splitter valve. I understand your caveat (trap), and can live with the fact that I MUST neutral the splitter valve before using any other downstream hydraulic function in the loop.

Man...this is a great site!

 

[Farmerford]

John:

You are part way there, but not quite all the way. The exhaust circuit of the LS valve (as well as most other valves that are not power beyond) is exposed to downstream pressure even when the LS spool is in neutral. Therefore, even if the LS spool is in neutral when you lift the TPH, the buildup in pressure in the supply line from the TPH, through the LS valve, through the FEL valve, and back to the pump is "seen" in the exhaust galleries of the LS valve. And the relatively fragile o-rings around the ends of the spool that seal the exhaust galleries from the outside of the LS valve can't tolerate more that a few hundred pounds of pressure (at most).

A power beyond valve, like your FEL valve, separates the exhaust galleries from any fluid under pressure (other than the very low pressure needed to get exhaust fluid back to the tank). Therefore, your FEL valve can be upstream of the TPH valve because the backpressure from the TPH stays in the power beyond circuit in the FEL (which does not communicate with the exhaust galleries in the FEL valve).

But the LS valve is not power beyond, so it cannot have any restriction on flow (like the TPH) from the out port back to the tank.


Greg will connect his LS valve to the work ports of the FEL curl/dump spool. That way, his LS valve will carry fluid only when the curl/dump spool is shifted and, unless the TPH is raised at the same time, the return fluid from the LS valve (whether its spool is shifted or not) will have a direct, unrestricted path back to tank through the workport, into the FEL, and then out the FEL exhaust outlet to tank. When Greg wants to raise his TPH he will center the curl/dump spool, which takes the LS valve out of the circuit entirely, so that the LS valve will not "see" the pressure rise in the FEL valve caused by the operation of the TPH.

In your case, if the LS valve is in the power beyond circuit of the FEL valve, fluid will flow through it all the time, and raising the TPH will restrict that fluid's path back to tank, raising the pressure in the exhaust galleries.

If that's confusing, shoot me a question and I will try to clear it up when I check back in a couple of days.

 

[gdib]

Thanks Farmer,
Really appreciate your feedback, Not having much of a background in hydraulics, I have spend a good deal of time going online and reading what´s in the forums. I have two questions about your posts:
1) Upon delivery of my 3400, I was given the operators manuals for both the tractor and the FEL. Neither explains the LA463 FEL setup. You suggest hooking the splitter to the A and B port of the bucket spool. Where are those ports on the valve? I attached pics of a top view and bottoms-up view of the valve
2) You mention the risk of back pressure with the use of 3ph. It seems easy enough to remember not to use the 3ph at the same time as splitting a log. But, wouldn't that all be eliminated if the hydraulic return went into the port plug? This plug mounts on the hydraulic fill underneath the seat and would have to be purchased and installed separately
Thanks again for your help.
greg

 

[land_lord333]

go to baumhydraulics.com and there is a calculator that will tell you the ton and the cycle time with any cylinder you want.

 

[Bill Barrett]

go to baumhydraulics.com and there is a calculator that will tell you the ton and the cycle time with any cylinder you want.

Great web site thanks!

 

[ride_bmws]

OK guys. I've been trying to figure this one out. I just got a 3pt log splitter for my B7800. I hooked it to my FEL and it works, but....it's very slow. The QDs up there are only 1/4" , the hoses for the LS are 1/2". I assume if I connect the splitter to a full size 1/2' line circuit that it would work faster. Is this correct? If so, how can I run hoses to the rear of the tractor with the PB circuit and not damage anything? Do I need a ned a new valve on the splitter that is PB capable?