Hello All; I have a early 1980's Barko 350 Log Loader that is having a hydraulic issue. Boom power was fine when we got it a few months ago and then it started to periodically lose power to the boom. We did find a 2 1/4 inch suction line that was collapsed and we replaced it and drained the hydraulic tank and cleaned the filters and replaced the old oil with new oil(400 plus liters). We started it and had boom power like before and then hardly anything unless we rev'ed the motor to max. That only produced a slow rising of the boom. Does anyone know anything about Barko's hydraulic systems?
have you put a pressure gauge on the pump?
Do you have gear pumps or piston pumps?
I'm betting a stack gear pump, all open center. Probably a bad port relief valve for the boom cylinder. Could be the pump went south from cavitation trying to suck through a flat hose though. Pictures?
It would be a double section vickers vane pump , one for main and one for jib. A third pump is a piton pump / motor closed loop for swing. The main boom port relief is likely bad if mb is actually the only malfunctions. There will also be a valve section corresponding to each pump section. So if all function on mb valve section show low pressure then suspect the main relief in inlet section. I seem to recall gressen valves were used on this model, either gressen or commercial the set up is the same.
Pump pressure was consistent. According to a brochure I found online it has a tandem pump, one single pump and one swing pump with control valves that are stack type Gresen V42 with main system relief and safety port reliefs for each control function.
If you can get to it easy, swap the port reliefs in the boom valve section (if it has two) I doubt you do much boom down pressure.......
Picture 1 is the filter housing that has a cartridge style filter in it about 5.5 inches tall, it had black goo in it. I have requested one from Barko but haven't heard back. Picture 2 is a valve from the top left hand pump on the back of the engine. It had black goo in it, and there was no o - rings inside of it on the shaft. Should there be???