Thumb has worked flawlessly for years, with the rare replacement of thumb circuit relays. Recently the the quit retracting. thought it was a relay replaced relays and a bad fuse, now, no retract or extend. Nothing appears to be burn or have gotten hot. Any ideas ?
Good day Do you have a schematic that way we can help? Kind regards Uffex
That system was a custom build that was done by Weldco to jack up the cost of installing a thumb. There were no relays and Weldco moved all their manufacturing back to Canada. I believe the relays came from Grainger. You can do away with the box and hook the wires from the handle up directly to the solenoids on the D3 valve if you can't find replacement relays.
What machine is this on? You say it would close before but not retract and after replacing both relays neither way works? If so, check your new relays. Like John C says the relays are not needed at all. The wires from the thumb switch can be wired directly to the DO3 valve. Also, find the DO3 valve and push the pin in on the end of the spool while the machine is running just to confirm it's not a hydraulic problem.