I'm having a thumb and quick-attach coupler installed on my dipper, and I'm talking to the shop owner about it. He says he intends to install a relief valve. Can anyone tell me why you would need a relief valve in a thumb circuit? I alway thought, because I was taught, that the main system relief is all that is necessary, and that it sets the operating pressure for the entire system. What is he trying to sell me? I'm having the work done for me so I don't have to take time off of my day job, which is the one that pays the bills.
The relief valve is needed so the bucket can over power the thumb. That way you can curl the bucket with load and not damage bucket pins or thumb. My Kubota does not have relief valve on thumb so I release thumb while curling bucket. I think he's doing it right just a bit more $. check out thread "Thumb problems KX-71 " think it was started 2012
Yep, when you curl the bucket back into the thumb, especially when you have a bite and just need to give it a nudge to tighten your grip... you can easily develop enough pressure from the bucket force to either blow a hydraulic hose or explode the cylinder barrel. I have seen both, many times. On an old JD 690B the cylinder barrel cracked from where the hose port was welded on the butt the full length of the cylinder and opened up at the gland. Sounded like a couple sticks of dynamite going off. It was lucky it was a cold day, the operator had the window down on the cab. Blew about five gallons of hot oil all over the front of the machine.
Thanks guys. I guess I've just never pushed the rentals I've had in the past that hard to see the thumb move.
Beautiful job! Hydraulic thumb and wedge quick-attach installed, and a new 12" trench bucket.
Sweet!
I highly recommend these folks. Quality work. reasonable prices, and timely delivery. Naico Fabrication Products in Parkland, WA. Tel. 253.405.8315
Looks good. I got a line ona 12" bucket too but I need to conver it to a wain roy qa for mine. Soon enough.
Very nice, when you get time post a pic of how they installed the relief valve & some of the plumbing. Thanks
Yes, I will do that. But first I have to find out why now I smell rubber burning when I start travelling (I have steel tracks). Either direction, doesn't matter. I haven't had time to dig into it yet, won't be for about a week. Meanwhile I'll call the shop that did the installation.
I tried to get some pics of the plumbing but very compact and awkward to get a phone in there (I'll take a camera next time), but what he did is install a toggle switch so I can use the blade circuit for operating the thumb. I can alternate back and forth. Never did figure out what the burning rubber smell was, searched all over, checked all wiring & hoses - nothing, and it has since gone away.
I picked up this bad boy today to compliment the thumb for blackberry, underbrush, and ivy removal.
]I picked up this bad boy today to compliment the thumb for blackberry, underbrush, and ivy removal. It also works great for removing pond weed, I made one much lighter duty than yours to remove that green choking pond weed.