3 pt. backhoe

The hydraulic hoses plug into quick connects fed with a single spool valve under the seat. I put the valve in the up position and it feed fluid to the backhoe. The out riggers, boom and bucket move around fine until I put a load on it and then the valve pops to the neutral position.

There is a inline pressure requlator on the supply hose. By backing off on the regulator I can keep the valve from poping off but there's not enough pressure to do any real work.

Am I doing something wrong or do I have an equipment problem? Thanks, in advance, to anyone that will try to straighten me out. Bill

I do have a qualification though. It would be a good idea to determine how the valve that feeds the hoe is plumbed into the system. I'm taking a guess that the valve is feed from an auxiliary system port and a diverter valve selects between the auxiliary and remote (3ph) systems. I'm also guessing that return oil to that valve is routed directly to the sump.

If so, there really is no issue. The valve probably is similar to one used for log splitters where it's desirable for a valve to release at high pressures. Many of these valves have adjustable relief pressures, but I don't know if increasing the relief pressure also increases the detent release point. An adjustment may provide a better solution than a bungee cord.

However, the auxiliary system return oil may be routed into the remote high-pressure line. That's a common hookup, because then auxiliary system devices and the 3ph may be operated without changing the diverter valve. In such systems, the auxiliary-system spooling-valve assembly should have power beyond capability. Power beyond protects exhaust oil parts of the valve assembly against the high pressures that may result if it were opened while the 3ph was in lift mode.

I'd guess that the valve that feeds the hoe is not a power beyond type, and its exhaust galley may not be designed for high pressures. Such a valve used in this type hookup can be damaged if the 3ph is in lift and the valve is then opened. It's a risk, and one solution is just to assume that the 3ph is never going to be bumped into lift mode, or that the auxiliary valve is designed to withstand for such an application.

A couple of further comments: Hoe equipped tractors should be loader equipped--it's a safety issue. In addition, 3ph hoes all should have mounts that lock down the hitch. Otherwise, a person in the hoe seat gets a rapid ride upward if the hitch gets bumped into lift or a draft mode activated. Of course, if the hoe return oil goes directly to the sump, then the 3ph can't operated and the issue is irrelevant. That's another reason for being sure how the auxiliary system is plumbed.