Backhoe BH77 Tech Manual?

[caspar3259]

I'm looking for someone who has a technical manual / repair manual on the Kubota BH77 backhoe.

I suspect my dipperstick cylinder's relief valve is set too low, so I would like to find out what PSI it should be as well as what the PSI should be for the other cylinders. Is this also what the sometimes call the "breakout force"??

Here's the problem I observe: if I extend the backhoe and set the bucket on the ground, then try lowering the boom, the dipperstick cylinder will compress. Likewise if I curl the bucket against something difficult to move, the dipperstick cylinder compresses.

It sure seems like the dipperstick cylinder is giving way too easily and not allowing the other cylinders to exert full digging force.

thanks,

-Jeff

 

[Verticaltrx]

Sounds to me like there is some air in the cylinders. When the valve is in the neutral position, the spool is closed and no fluid can pass, i.e. there is no relief. If the cylinder is compressing with the valve in neutral then either there is air in the cylinder or you have a bad seal. If it's just air, it should in theory eventually make its way out. If not you can slightly loosen the fittings on the cylinder, push fluid through it, then close them back down. (similar to bleeding brakes in a car)

 

[caspar3259]

I don't think it's air in the system. There is no spongy feel and the BH has many hours of use. I also went through a purge process last week to rule that out.

Yes, I suppose it could be a bad control valve... but I'm not sure how to determine that.

I think the dealer doesn't believe me right now. That's why I want to collect as much info as possible to "make my case".

-Jeff