Bleeding a new backhoe attachment

campkubota · Aug 20, 2011

I have attached a Jinma JW-03 with it's own hydraulic pump to my Kubota.
I have no manual and for the life of me cannot get the system bleed of air.
There must be something I'm doing wrong, I have it working and the next day nothing. Any suggestions would be appreciated.

J_J · Aug 20, 2011

First, check to make sure all the hoses are tight. You might be sucking air.

If it has it's own tank, then the air should purge to tank.

It is also possible to suck in air through rod seals if conditions are right.

Is the suction outlet low or high on the tank, and is the level of fluid correct?

campkubota · Aug 21, 2011

Thanks JJ
The suction is located lower in the tank and I have been cracking the hose
connections to try to bleed air. I've check the fluid level and thought it was low and added, when I do get one of the cylnders to move fluid streams out the cap.
This morning I'm going to make sure all hose connections are tight and fluid level is ok. I'll be back to let you know how it goes.
Thanks again.

J_J · Aug 21, 2011

You don't need to crack any hoses, as the fluid will push the air out as you extend and retract the cyl. You may have to cycle the cyl many times to expel all the air.

If you have a hyd gage, install it in the IN port of the BH to monitor and use it for trouble shooting, or make it so it is able to just plug into a QD to check pressure.

Is the PTO pump a Prince pump. The pressure on those pumps is about 2200 to 2500 psi. The GPM's determine the speed of operating, and there maybe some circuits in the BH that have restrictors in them.

Is your hyd tank above or below the pump? I am thinking you are losing your prime on the PTO pump, cause by an air leak.

If you use tractor hyd, you will get more power out of the hyd system, assuming the tractor hyd pressure is around 2800 to 3000 psi.

Brad_Blazer · Aug 21, 2011

Clean the suction strainer and check the suction line from the tank to the pump for unobstructed flow by disconnecting the hose at the pump inlet and draining some fluid into a clean container. If you have free flow to the pump inlet there should be no problem with air in the system.

campkubota · Sep 20, 2011

Thanks guys for the help, I'll admit what I did, I think I have a long way to go.
I checked the oil level and it was low, as I was working the air out of the cylnders the oil would spray out of the breather holes in the cap so I wouln't fill the tank and that was my problem, I was pushing air and oil at the same time from the pump. Now that I keep the oil tank full the system is bleeding just fine and I am keeping a close eye on the oil level until all the air is out.