I have a Doosan SL75-V excavator. It has factory plumbing out to the bucket. I put a hyd thumb on it. The problem is, it will only operate the thumb in 1 direction. I assume it was set up for a breaker rather than a thumb. Is there an easy solution to solve this TIA for any help. Drip
Try checking to see if you have a 2-way manual valve installed in the hydraulic lines close to the control valve for the auxiliary attachment. This 2 way valve would usually be installed as a factory option but if you don't have this then you may need to install one. See diagrams attached for location and variations, Doosan call them "switch Valves". You would manually turn the valve to 1 of 2 positions depending on what attachment you wanted to operate between, typically breaker or nibbler Best regards
Thank you so much. Your advice is dead on. I found the switching valve. I was trying to use the thumb control on the right hand joystick. Still no change. I took it to a local heavy equipment shop, ( Wards in Greensburg, IN ) & there ace mechanic Blaine looked it over for me. Before I unloaded it, he asked if he could try it. I said sure, He hopped in it & the thumb worked perfectly in both directions. Turns out, it is operated by the foot pedal in the cab & not the thumb switch. Thanx again for your info & help. Drip