b7200 hydraulic relief adjustment

[fatjay]

I was lifting a load with the bucket the other day and I fell short of what the loader was supposed to be able to lift, but was not dead heading the pump and had no change in rpm speed. Which tells me there must be some bypass to avoid overloading the pump, some sort of relief valve that I'm not aware of. I searched online but didn't come up with any results. I don't think it's fluid bypass in the cylinders as there's no leakage.

 

[bdhsfz6]

I'm not sure if it's the same on the B7200 but I had that problem with my old 1979 B7100HST. There were two types of hydraulic systems used for the FEL on that model. One used the internal hydraulic pump and the other had an external pump coupled to the engine crankshaft on the front of the tractor. Mine had the external pump which I had to rebuild due to wear when the pressure dropped.

The pressure relief valve on the B7100 was located on the front of the 2 spool FEL valve. Some were adjustable with an Allen wrench and some were not. Mine wasn't but I was able to boost the pressure by removing the spring and shimming it with a washer. If you do this, check the pressure to make sure you don't exceed the cylinder & hose limits.

Hope this helps.

 

[rScotty]

I was lifting a load with the bucket the other day and I fell short of what the loader was supposed to be able to lift, but was not dead heading the pump and had no change in rpm speed. Which tells me there must be some bypass to avoid overloading the pump, some sort of relief valve that I'm not aware of. I searched online but didn't come up with any results. I don't think it's fluid bypass in the cylinders as there's no leakage.

You are on the right track. The relief valve is usually built into the FEL control valve. Look for a protrusion on valve body located on the opposite end from the levers. Usually when the relief valve actuates you can feel or hear it.
The pressure that it actuates at is directly proportional to the lifting force of course, and the setting us usually by means of shims or adjustments to a compression spring. And springs get old.....

One way to adjust the relief is to put a hydraulic T fitting and a 5000 psi gauge right there on the inlet to the FEL control valve. That way you can know for sure, and also use the gauge pressure to adjust the relief valve.
Cost of a hydrulic T (not a plumbers T) and a good gauge runs about $50.
rScotty

 

[fatjay]

It's using the internal pump, not an external pump. It's tapping the hydraulic block on the right side. I'll take a look at the FEL control valve and probably take a picture. I looked at it but nothing was immediately apparent as far as adjustments.