Knuckleboom Crane: Hydraulic System 1st Test!

I didn’t have the outriggers hooked up yet, but I was excited to give the hydraulic system a test, so I gave everything a quick check, filled up the second tank with oil and fired it up!  After a bit of idling with the PTO engaged, the reserve tank started gushing hydraulic fluid from the top at the filler neck!!!! What the heck was going on???

I shut everything off, examined everything, and thought about it a bit.  It seemed that hydraulic fluid was filling up the second tank, and not getting back to the main tank quick enough.  Hmmm.  In looking at what I had done, the filter in the second tank was acting as a restrictor, and limiting the speed that the fluid can drain back to the main tank.  So I switched the hoses so that the return line from the crane valve body connected to the filter going into the tank, and then flows from that tank to the main tank via a ¾” hose.

See the new schematic:

hydraulic schematic 2