On my Hitachi EX120-2 I’ve got hydraulics to my thumb. The lines are 3/4” steel and #12 4 wire hoses. At the end of the stick are boxes with a flow control. Foot pedal in the cab is a 3 way pilot valve. On/off/on Excuse my ignorance- but how do I determine if I can run a hammer off this set up? Currently my hydraulic thumb is reduced down to #8 hoses but the piping #12 right to the ends. I’ve worked on machines my whole life but never owned my own excavator. I’ve worked on hammers before but never had to repair or install one on a machine that was not already set up for one. I am assuming that most sales people will just sell me the proper size regardless of if it will actually work. Thanks in advance. Syleng1
I have a dedicated return to the tank for my hoe pack on the 120, and a pair of selector valves that lock off the thumb. It is a '98 120 and is more similar to the -3 I think. The return line was a kit from John Deere.
@Syleng1 , if you have factory plumbing you could remove plug #3 (on screenshot) and install a shut off valve and run a hose to the return piping at the hydraulic tank .Open the valve when running the hammer , close it when running the thumb. Same concept as @skyking1 has on his 120. .
Once your machine has thumb hydraulic pipes, your machine can use thumb hydraulic pipes to mount the hammer for use.
Took this yesterday. The dedicated return and one of the valves.
Thanks- very close to what I’ve got. Thank you skyking1
Thank you for this info Lachau!
Diesel Dave- this configuration is what I have. I also have control valves for fluid flow on both sides. Thanks for this detail.
Highly recommended that breakers are hooked up with one way flow with return going back to tank, bypassing the main control valve. Control valve adds a ton of restriction on the return flow, I've seen it add a few hundred PSI in some cases. Connect the jump hoses from the breaker to machine directly or use a high quality quick coupler. You want back pressure to be as low as possible. Have someone with a flowmeter set the relief and flow on your aux circuit to match the breaker. Its well worth it when you consider its a couple grand to reseal a breaker. From my personal experience most breakers fail because of incorrect setup or cheap and restrictive couplers.
More detail from Hitachi documents.
So, 92U 3406 - what you are suggestion is maybe add a “3rd line”? Make one of the aux lines from the thumb a dedicated pressure line and set that and install a separate open hydraulic line as the return or dump that back to the tank (I’m guessing thru the return manifold.) not allowing return flow thru the aux valve. Set the high pressure side setting and then maybe mount a removable block under the side of the foot pedal that will not be used so it cannot engage the backside of the thumb. Thank you, Syleng1
Very good advice. IMO the return line should always go to the tank in case something like a cheap quick coupler grenades and sends shrapnel down the line or some other metal debris. You want that debris to dump into the tank not go through anything else.
Mine was a kit from John Deere, you can look up the part numbers for the hard lines and hoses and hold downs.
If your machine isn't plumbed with a one-way valve all you really need is a manual 3 way diverter valve mounted to the back of the boom. Plumb the return line from the breaker into the appropriate port. From the 2 remaining ports run a line to the original return on the main control valve and a line from the other port to the tank. More or less the purpose of the diverter is to direct the return flow to either the tank or back through the main control valve so you can easily switch between thumb and breaker. If you don't have the ability to adjust flow on the aux circuit you can always plumb in a pair of PRVs on the pilot lines. Those will regulate the available pressure to move the aux spool thus regulating the flow. This kind of work is a little bit beyond the average machine owner or operator so if you're not sure I'd have a hydraulic or heavy equipment shop handle it. Shouldn't cost much, couple thousand at most would be my best guess.
I’ve been a heavy equipment certified welder / mechanic for over 30 years. I’m good. The only issue is in my head. Because it is my machine I am second guessing everything. Prime example is yesterday I noticed a leak from underneath the machine. My gut said, “center joint.” My brain said everything but. If this was a client I would had said center joint and gave the customer the option to move forward with that diagnosis. But because it was mine, I had to go nuts checking everything. It’s a 35 year old machine that was abused before i got it. Crazy how the brain works. SN: my repair history is on machines 40 ton and under. Excavators, bull dozier, backhoes and farm equipment. Typically trailer moved machines. Here in New England stuff that gets taken apart to move is far and few in between.