Life without a backhoe would be impossible. I got the job of rebuilding these 2 cylinders off a Clark. Heat on the nut just seem to make no difference, they are a cast steel of some kind. Finally had to make a tool and use the hoe bucket to turn them, 1/6 turn at a time. A Case 530 draw-bar and a 955 steering clutch flange made up the tool. One nut came off particularly hard, although the very fine thread did not look galled or damaged. Used an old Cat 955 loader frame for a fixture. After 2 tough days we had them both apart and could move inside out of the heat:drinkup. Phil
Yep, that U cup seal looks like it's a bit tired.
Yes the piston seals were bad, they came out in pieces on the other cylinder. Hope not to have to go through that again. Cylinders are back on and working okay; on to the fork dropping problem. Phil
We used to tighten the u- bolts on camelback Macks with a 1" ratchet and a trackhoe. (Don't tell Mac tools)
Life is easier with Never-Seize!
Ha....them old 955's keep right on werkn,,,, one way or another..yup!
Hey Phil, just what Clark machine is that off of? Just from the looks of that cylinder with the bohunkin cast steel gland cap, I'm guessing it's off a machine from back in the 70's maybe?
I'm glad I kept that frame grandpa. Put it in the Ranger last year, when scrap was up, but it put her down on her knees so we lifted it back out. She's here to stay now. Phil
Can't remember ATCO what model she is but she's big. Chap uses it to lift 40' sea containers. Originally had a 318 industrial but it was replaced with a 453/Allison power-train. Can't find the finished picture but there's a few here: http://www.shopfloortalk.com/forums/showthread.php?t=19311&highlight=Clark+reserection
Yep, good size Clarklift. So the fork cylinder drifts down? I noticed at the other forum you rebuilt the lift cylinder. If it's still drifting down, got a problem with the valve spool or relief valve on lift cylinder. Those single acting forklift cylinders typically didn't use a holding valve.
The machine had a slight drift to the tilt cylinders, for the past year, but the new packing supplied by the owner has remedied that. The problem with the mast cylinder started just before we took the tilt cylinders off. Owner said he was doing something he probably should not have done. Now when the lift lever is pulled normally, the mast cylinder(forks) abruptly and violently drop at least a foot, before starting to go up. If the lever is pulled back rapidly, all is okay. We have taken the control valve off and are checking out every valve/spring inside it. The velocity fuse or whatever it's called, at the base of the mast cylinder is apparently not working. I could see no other valve(s) on route to the control valve. I've heard reference to a 'poppet valve'. The mast cylinder has a vent line, to the tank, via the control valve. Phil
Yes, it would have a vent line at the top of the cylinder. But vent probably isn't proper description of what it's purpose is, not sure what term would be correct. That line would be connected to the return circuit of the hyd system. But what it does is to allow oil to go in and out of the rod side of the single acting lift cylinder. This oil serves no purpose in lifting or lowering, but helps keep the cylinder can lubricated on the rod side and prevents atmospheric condensation on the rod side of the piston. I understand what your saying about the cylinder dropping when slightly cracking the lift control valve. Not certain what's causing that. I suppose the tilt circuit doesn't have this problem? Only lift circuit? Your problem may very well be the velocity fuse not working proper. The main purpose of the velocity fuse is to control a rapid descent of the lift cylinder if the hose that feeds the lift cylinder were to burst. If the hose were to fail, the velocity fuse would keep the load from suddenly slamming to the ground since these systems don't use holding valves. The problem you are having is simple physics. There is a great amount of pressure on the oil in the cylinder when it's raised. When you just slightly crack open the lift spool, pressure being sent out the lift hose from the spool is minimal at first, it takes a few moments for pressure to build in the delivery line from the spool. Well, since the pressure in the cylinder is greater, it's going to drop from oil exiting out the lift hose from the weak pressure coming from valve until pressure is matched by delivery from valve. This all happens in probably less than a second. Something has to "hold" the oil in the cylinder while the delivery from valve builds sufficient pressure to gently raise the load on the lift cylinder. That would most likely be done by a poppet valve in the power beyond galley of the control valve. You should see a plug in the center of the lift valve section, right next to the port for the lift cylinder hose connection. Under that plug should be the poppet valve. Should have a spring and a poppet spool under the plug. Inspect the seat surface of the poppet spool and the seat surface that it mates with inside the valve body.
have you ever seen those komatsu excavator teeth that are held on by nuts and bolts? very similar tools are used for that. it is called the KVX.
Got the control valve completely apart last night. The valve just inside the supply line(P) connection was stuck and had to be tapped out with a hammer/punch. On the other end of the valve body, by the return ports, is a valve inside a sleeve; it was stuck and had to be pushed out by hand. The valve inside the lift spool looks good. I did not take the tilt spool apart. All springs look okay. The lift circuit works perfectly as does the mast lower function. The local forklift dealer has been quite supportive with the owner, so I might see if they have any info on this valve today. What do you think ATCO? Phil
load check In heavy industry this valve would be referred to as a "load check valve" and it function is just as you describe-it holds the load until the pump can supply enough pressure to overcome the load. I suspect you have found your problem "valve inside was stuck and had to be tapped out". Tom
Well, one thing's for certain...we know it's a Hydreco VZ65X1 valve. :tong Nice work man. And another thing, I'd wager you growled pulling that big heavy thing out of the machine. :yup That spool looking thing with the tapered end does look like a load check poppet. And that arrowhead looking thing with the small stiff spring looks like the master relief poppet. I'd bet if you get everything polished up and working smoothly in the bores, intall some new seals, you'll be good to go.
Thanks ATCO and others for your comments. Not familiar with forklifts. We noticed the tilt spool is very tight in the bore when removing/installing, once in it's place it's okay. Don't remember that when I replaced the spool seals a year ago. Going to put it back together today, and hopefully it works. Phil
Woah! That is tight! How would they normally remove it? Tim
There is a wrench made for that type of nut, we are using it in one picture. They are usually adjustable. Didn't take a chance pushing on it with the hoe. My dad had it from years ago, for Cat D8 2U final drives. Phil