I have an old Daewoo Solar 70III excavator I use around my property. I recently picked up hydraulic breaker that will fit it. My machine is already equiped with a hydraulic thumb and has a switch in the cab for a breaker. My question is, does the hydraulic breaker run off of the lines already installed for the the thumb or is there a separate control solenoid/valve for the breaker. I am having a hard time finding any manuals or documentation for this machine. Any help greatly appreciated
Yes it should be able to run off those lines as long as they aren't small diameter. On a smaller machine like that I'd want to see about a #12 size line on the return. Hopefully your machine is able to produce enough flow to operate it. The huge thing with attachments like breakers and compactors is they do not like high backpressure. They absolutely require one way flow with the return routed directly to the hydraulic tank. If your machine doesn't have that option it is easy enough to install a 3 way valve on the return to select return through the control valve or a bypass directly to the tank. The breaker will often require the auxillary relief be set higher than thumb pressure too; check your breaker's pressure/flow requirements. To avoid having to adjust the relief every time you switch, you may have to plumb the thumb the opposite way so that you close it using the line on the return side. That way you can leave that side's relief set low enough to not damage the thumb if you overpower it with the bucket and the other side will be high enough to provide sufficient pressure to run the breaker. Also, invest in decent couplers. Non-locking threaded couplers are not good. Flat faced skid steer style couplers would be a good choice.
Thanks for the reply and advice. I actually found a shop manual online and am waiting for it to arrive. It appears that my machine has separate controls for the thumb and a breaker. Is it possible it has separate valve that just needs lines run? I am by no means a hydraulic expert but I thought lines for the thumb cylinder were the same pressure, just pressurized one side of the piston or the other. Is it the same with the breaker or am I completely off base?
I've no experience with Daewoo so I can't provide insight there. Pressure is a result of resistance to flow. In other words the more load on a cylinder, the more pressure needed to move the load. The auxillary circuit relief acts as a safety limiter, it will only allow you to load the circuit up to whatever pressure its been set to. Normally the relief for thumb use is set low enough that you can overpower it with the bucket and not damage the thumb and thumb cylinder. Unfortunately a breaker usually requires (in my personal experience anyways) about 1000-1500 PSI more pressure to run than a thumb (again, check the pressure specs for your breaker). That higher pressure setting, if you were to try and use the thumb, could damage the cylinder and thumb if you powered the bucket into it. That's why I mentioned you may have to reverse the 2 lines on the thumb. That way you can set the pressure relief on the line into the breaker at its proper setting and then set the relief on the other line (which during thumb use will now be attached to the barrel end of the thumb cylinder) to the lower pressure setting needed for the thumb. The breaker will only use 1 way flow (out of the main control valve, to the breaker, return to the hydraulic tank). The thumb will use 2 way flow (both lines are capable of supply and return).