Austin Western Crane 220 : boom not operating.

I'm looking at a crane that has been sitting for years. The boom is presently extended and angled about 20 degrees, just enough to be about 13' total width, which is too wide to transport according to the trucker we called. So we have to get it to turn first.

Engine (detroit) starts and runs great. The outrigging and steering (front/back) works but slowly and sometimes jerky.

The boom controls do not work at all, no twitches, nada. Except that when I operated one of them (boom up) oil shot out of a open hole in the line near the base of the boom. We threaded a plug into that, no more leak. Anyway, that was proof of some pressure. After that, operating any of the boom controls gives zero response. no movement, no detectable noise from pump, hoses, valves. just seems dead.

In order to get the boom to swing we tried attaching a chain to it and dragging with a truck (with the swing control lever engaged) but it wouldn't budge at all.

Diagnosing.

There are two hydraulic pumps operating from a single tank. The smaller pump is belt driven and supplies the steering and outrigger controls. The larger pump is directly coupled to the engine and supplies the boom controls. Both pumps are fed by the same supply hose from the tank, with a Y in it.

As far as I can tell, both systems are independent after each pump, and back to the tank, but I could be mistaken about that. Assuming they are independent, I think it is a good sign that there was oil squirting out when I operated the one boom control, because that indicates the main pump must be doing something.

One theory is that there may be a clog somewhere, possibly a filter in the tank. That doesn't seem quite right though since the smaller pump is functioning (albeit slowly). I would expect the controls on the larger system to at least twitch.

I guess it could be either the main controls or the main pump.

I'm not a hydraulics expert so not sure what to check next. advice appreciated.

Also anyone know about these old austin western cranes and can explain the hydraulic system? where filters are and how to change them?

since I didn't mention it, yes there is plenty of hydraulic oil in the tank. I was checking it and adding as needed the whole time.

There is almost always one or several house or boom slew locks or brakes on the cranes I've run. Might or might not be a dead man switch on the seat or a master hydraulic lever or valve too. Usually a lever on the left by the seat in the ones I know. Not familiar with that model though.

I did notice some kind of hydraulic device behind the seat with two larger lines and two small lines. I didn't fully trace the lines, but its possible that one of the smaller ones came from the seat.

Also I remember that there was a small line that was supposed to thread into the engine intake but the nut on it was too small. So I am developing a theory that there may be a seat switch that is vacuum operated to actuate a valve for the main hydraulics. Or just as likely that intake line is for a guage.

The crane is 2 hours from me, so I can't easily go look.

Anyone here that has operated one of these old Austin Western cranes that can shed some light?