Hey there, I was wondering if anyone has experience setting up a hydraulic quick coupler that has three lines. I bought a coupler at auction for 250$ that appears in decent shape. It says it is off a Kobelco sk135 which is the machine we have. It was so cheap I didn't look at it much before buying. When I got it home I realized it has three hydraulic lines plumbed into the coupler. I was only expecting to see two lines. From what I've gathered most couplers tee into the pilot system and have pressure running constant from the pilot system to port A which keeps the coupler piston extended all the time. Then when you actuate the the valve to release the coupler it send pressure to port B to retract the pin grabber. and port A just dumps to tank. These are some schematics I found online. Part I'm confused about is mine has three lines running to it. I also can't find an identification plate on the coupler so who knows what brand it is. Ill post a picture of the logo on the side of the coupler.
Generally hydraulic pin grabber couplers are plumbed into a port on the main hydraulic pump that supplies the bucket or plumbed into the curl side of the bucket cylinder.
This type does not have a fixed nameplate and will only match different models. The quick connector is divided into hydraulic and mechanical devices. I attach the connector without hydraulic below.
The emblem kind of looks like an old Rammer Hammer but I didn't know they ever made quick couplers. As for the 3 hydraulic lines my guess would be that it has a pilot operated holding valve in the cylinder since it has no front pin latch or spring safeties. If that's the case you would have to send pilot oil down the third line in order to unlock it. Did you get the valve too or just the coupler?
You take a picture of the junction box with 3 hydraulic lines to see what it looks like.
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I appreciate the responses. I apologize for my delay got busy with some other projects in the shop. I took apart the coupler so I can get a better look at it. It appears there’s two small hydraulic rams that kick a bar out of the way so that the coupler can retract and they are spring loaded so I think those are just one way flow. Other two lines look like they run the two way flow of the main piston. While I have it apart I may try to get replacement seals. Main piston has a couple dots of rust on the chrome. Probably can polish it and run it but if it starts to leak I may have to machine a new piece of chrome bar for it. Question is now for plumbing it. Do these typically run off the pilot port on the pump so there is pressure all the time to the main ram? The smaller pistons at the base when extended would move the stop out of the way so that the ram can open up so I think I could attach that line to the same circuit as the line that retracts the piston.
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