Our 160g has auxilliary hydraulics with a thumb, we have rented a breaker (not done this before). The breaker works good for a couple hours, then slows down and is hard to start (as in you push the button several times to get it to fire). Makes me think it's getting hot, but there is no gauge/warning light that indicates anything wrong. So, could it be in 2 way mode and is building up heat? Is there a valve of some kind to change it to one way for the hammer? I see nothing in the manual other than choosing attachments on the monitor under work mode. We've tried work modes labeled breaker 1 and breaker 2.
Assuming the machine has factory plumbing , when Breaker 1 or 2 is chosen in the monitor the selector valve should direct the return oil back to the hydraulic filter then tank. Generally when a thumb is installed , the circuit relief at the auxiliary valve port that supplies the thumb cylinder barrel end is set relatively low. If that same auxiliary valve port supplies the breaker , the breaker operating pressure maybe be running very close to that lower circuit relief valve setting and affecting the breaker performance when the oil is warm. What model breaker do you have rented ?
It's an NPK model gh-7, I don't know if the auxiliary is deere or aftermarket? Thumb is a Tag.
NPK GH7 operating pressure is 2,600 psi. Is the barrel end of the thumb cylinder connected to the left side auxiliary plumbing on the boom and stick ?
FYI, you can check hydraulic pressures through the monitor.
Yes, the extend port on the thumb cylinder goes to the left side piping. How would I look at pressures?
HEF member @John C. posted a video of the Hitachi Zx-6 (same as a Deere G series) monitor panel usage. . When in the service menu under Monitoring pull up “Pump 2 delivery pressure “. Turn the two hammer shut off valves on the dipperstick to the off position . At about 1/2 engine speed , operate the hammer control and read the pump 2 delivery pressure .
Pump 2 delivery pressure is 13-14 Mpa @ 1/2 throttle, if I converted right is about 2000 psi. Hydraulic temp is slowly climbing, hottest we've seen is 64 C. Cools back down to 56 C pretty quickly sitting idle. Would raising the pressure help? Is this done in the monitor or is there something mechanical to change?
Your mpa to psi conversion is correct. The circuit relief valve for the left side auxiliary boom tube should on the top of the main control valve. I highlighted in red on the screenshot below where the top circuit relief valve should be located. Turning clockwise one full turn of the top allen screw on the circuit relief valve should be plenty. You want to be at approximately 3500 psi (approx 1000 psi higher than the breaker normal operating pressure). Dont forget to turn the relief valve back to original position before using the thumb.
Turned the pressure up one turn, voila! This thing works great, temp stays down. Thanks Diesel Dave, you're the man!
To keep from changing relief pressures, rotate your thumb cylinder so the barrel end fitting is on the right side of the machine. That way you can set one relief for the thumb and the other relief for the hammer and leave them that way. A Deere installed thumb is mounted that way. That is what we do to all aftermarket excavator thumb installs that instruct you to install them to the left side. If it is not already installed, and you plan to run a hammer often, you might want to consider a combo kit for your stick (if not already installed) so you do not have to disconnect the thumb to run a hammer.
That's good to know, so where is the relief adjustment for the right side? My machine has the combo piping on the stick and had some big (2") flat face couplers on there to plug in an attachment. When I rented the hammer, they didn't have anything like that and said they always hook up with JIC fittings. Very slow and messy, I bet I lost a gallon of oil hooking it up. There should be a standard for couplers like there is with skid steer attachments.
The right side circuit relief valve is in the bottom of the control valve ,similar orientation as the top one. Generally speaking ,breakers (like your NPK GH7 rental) do not require a specific carrier circuit relief valve setting other than being set at a minimum of 1000 psi higher than the breaker operating pressure. I’m sure there are some inlet pressure sensitive breakers out there in the world but cross that bridge when needed.