Got a thumb on order and need couplers. I'm guessing this is a very common question - which ones do I buy? I did some online searching and came up with these numbers for the ones possibly on the machine. KV13884 sub for 4486229 KV13885 sub for 4486230 Also found listed: AT312877 Does that help narrow down what I would buy to plug into them? Thanks in advance I'm a novice to excavators...been using my old WD Allis Chalmers since the 90's for everything. Got tons of work done with that tractor, but it's amazing how fast and versatile this excavator and the Bobcat 873 are in comparison. Oh, the thumb is a 27" hydraulic: https://linvilleindustries.com/product/27-full-hydraulic-backhoe-thumb/
Be careful, the Hyd pressure on your machine according to specs is 3553 Psi and the thumb Cyl is only rated to 2500 Psi. Need to check the machine thumb valve and see if it has a adjustable relief on it.
Yes, you want to make sure that the bucket can overpower the thumb cylinder. The aux. should be adjustable, but want to make sure that you get that dialed in correctly.
Thanks guys I'll look around and find out where that is. Putting quick connects on a gauge should do the trick for setting it I'd imagine.
Make sure that however the thumb is plumbed in, whether factory valve or aftermarket kit, that there is a relief valve that allows oil from the butt end of the cylinder to vent to TANK, not just from one end of the cylinder to the other. I've seen it done wrong more than once, and the results can be catastrophic. Deere 690B loading stumps, popped the six inch thumb cylinder tube at the butt where the hose port was welded on, split full length to the gland. If it hadn't been cold with the cab door and front window closed up, I'm not sure the operator would have made it, the oil was hot enough to peel some of the paint. New cylinder, new relief valve plumbing, clean shorts, back to work.
Well the hydraulic cylinder was 2" too long, so a farm scrap took its place The thumb was well used immediately, and for the rest of the day