is a skid steer hydraulic tank pressurized

Hello,

I have a Mustang 940E skid steer, I have adapted it to fit a Kelley B-15 backhoe with a 3-point hitch adapter and some fabrication. I tried to power it off of the aux hydraulics and all was working well until the filter exploded (gasket let go).

When I adapted it to the skid steer, I wanted to put a filter in the return line just to ensure no "junk" got in my mustang's main fluid. I used a 3/4" NPT filter kit from surplus center (15 PSI bypass) for the return path. The backhoe is open center so fluid is constantly flowing from the inlet to the outlet. I was using the hoe today and when I applied some pressure to the cyls of the hoe, the filter in the return line let go. letting fluid go everywhere...

So did I exceed the 100 PSI maximum rating of the filter; I would have assumed that the return line would be day lighted back to the tank with no pressure; but it appears that there is pressure in the return. The return I was using is the return from the aux feed. The aux control lever was in the full forward direction (detent).

So is the "return" line pressurized, does the return line build pressure?

So is the return line back to the tank pressurized?

Thanks in advance!

is a skid steer hydraulic tank pressurized