Having experience with smaller double acting cylinders and forklift cylinders, we opted to swing our boom cylinders down in our excavator and attempted to change the seals out. Never in my life have I experienced such tight cylinders though! Literally takes a 4ft wrench just to get the rod to rotate in the bore and our CAT 257 skid steer will NOT pull the rod out of the cylinder at ALL. And that is with worn seals. We have both oil lines removed. I am not worried about the nut on the rod but if I cannot even get the rod out, we are stuck. Anyone have any advice for this or are we SOL? Rod is 3" and bore is 5" and 5ft long. I know there are some people that have built cylinders here. What tool do we need to buy or make to get this going?
First of all, what brand and size excavator are we talking about. Second, do you have the cylinders fully retracted?
CAT 225, cylinders were fully retracted and we thought they might be stuck in an area in the bore that is never used thus tight so we put all the lines back on and pushed them out to near full stroke. Only a small different in torque to rotate the rod but still no dice in pulling the rods from the barrels.
Well, I'm not sure why both cylinders are so tight in the barrel. Have you already got the gland removed from the end of cylinder and still can't pull rod out?
Cylinder Have you got the head seperated from the tube or are you tring to get the rod and piston to to pull the head out when it comes . The head needs to come loose first then pull the rod out keeping it lined up so it doesnt bind. If its still wont come take a chain and hook it with a little slack thru the rod pin hole and to the tube pin hole or back to the frame, plumb up a air line to the cylinder that you can regulate and start increasing preasure when it takes up slack in chain remove all air preasure and increase slack in chain and put preasure back to it and do it all over again untill it blows out dont stand in front of it !!!!!!!!!!!!and have it laying on plywood so it doesnt mess up the rod when it comes out. If you have the barrel still attached to the machine hold the rod with some kind of lift so it doesnt hit the ground as the chain is just to keep it from shooting out like a cannon litteraly.
Be very very carefull using air pressure. I saw a fitter send a 8 foot long 6 inch diameter rod through a workshop wall 15 feet away using workshop air. If HATCHEQUIP's instructions are followed to the letter you should be ok. You could also plumb a hydraulic line to your machine and force it out with hydraulic pressure. Very messy and wasteful of oil but not so explosive. Another method is to chain cylinder to an immovable object and chain a comealong or porta power to another immovable object and pull it out that way.
Not sure if this is the place but the story behind this is worth telling. This was back in the early eighties and the fitter was a man of considerable experience. He was using a hydraulic ram press to overahul a worn cylinder. The cylinder is chained down to the bed of the press securely and the rod eye is slipped over a two inch pin and locked down with a plate and 3/4 boly. The press is then jacked apart using an air operated hydraulic porta power set up. All went well until the last foot or so when the rod locked up and stalled out the press. Usual practice then is to fill the cylinder with oil and use a hand operated portapower to overcome the tight spot and the press is set up to catch the oil spilled. He decided to save time and plumbed in the workshop air with no regulation (125psi) and turn it on. The beast ay to describe the result is an explosion. Three heavy chains holding the cylinder broke and it hit the floor. The rod broke off the two inch pin and proceeded about 15 feet where it went through a timber framed plywood wall at about 30 inches above the floor into the engine rebuilding room next door where I was working. The foreman was surprised to see this thing appear in his small office space where luckily he was not sitting at the time. It took a forklift to get it out. The fitter was still standing with his hand on the air valve when we all rushed out to see what the hell was happening. I will never forget the look on his face.
I have seen it happen where the seals are so buggered that the seal has blown and gone down the side of the land on the piston causing the piston to bind in the cylinder and on some poorly designed rams where this has caused the piston to drag and ruin the barrel, the design of the cat rams will prevent this however. To remove the rod I would suggest to prop the ram level on a stand and set up a forklift or similar to catch the rod (with rubber on the tynes to prevent damage to the rod), cap the gland end hose on the machine and hook up the other end back to the cylinder, unbolt the gland and start the machine and using quick stabbing motions on the control valve slowly eject the rod from the end of the cylinder, this method would be a lot safer than using compressed air as when the rod and gland leave the barrel it will do so in a controlled manner and not fly out as when using compressed air, be aware that you will have a barrel full of oil to try to catch when the rod does come out though. You will need the appropriate tools to remove and retorque the rod nut ( cylinder bench or pin beam and torque multiplier etc ) if you dont have either of these, remove the complete cylinders and take them to someone who has the gear and knows what they are doing as the piston nuts are *#*#ing tight, if you think you may be able to undo them with a shifter or stilsons and a length of pipe you will be most dissapointed. Hope this helps.
Something we do to sticking rods and glands, we secure the end of the cylinder and use lumber to support the rod while in the barrel. Either blocks of 2x4's or 1x4's, what ever can support it on three sides, kind of a guide and to keep from damaging the barrel, chrome or threads. We then hook a come-along/ratchet hoist to start pulling the rod out and maintain pressure. When it starts to stick we will wiggle it a little up and down by hand or twist it with a pry bar to try to walk it down the barrel. If it stuck that bad then there is a good chance that the barrel is galled or the rod is bent. Hopefully it is just the worn seals wedging it. Best of luck, JCS
Stuck Rod We use a forklift to pull rods, chaining the cylinder to the bottom of the mast, and slide a big bar through the rod eye and over the forks (tie with a rope for no surprises, tie the rod to the forks, the eye to the rod, and the gland up too so it doesn't slide down and smash your fingers, rope around the top of the tube so when the rod pops out it won't fall and bust your toes ;-) Usually the cylinders are so worn they are squirting oil and the rod slides out pretty easy. Pushing side to side and wiggling usually helps it pop out the end (as well as getting it back together for reassembly - remember to recompress the teflon ring good on top of the rubber T underneath if it has that type seal... Are there any sharp edges inside the tube at the end or dents where a piston ring could be hanging, or a sharp edge groove from a retaining ring? I've had some cylinders where you had to use a little orange plastic filler ring in the slot to keep the piston from sticking at the end of the tube. I'd push it back down from where it's sticking and look in with a flashlight, look for edges and see why it's sticking. I'm curious too, how everyone gets the rod nuts loose. We're a small outfit (2 guys) so don't have sockets/wrenches bigger than 3 inches, so we torch out a home made wrench from 1" plate, stick a 20 foot cheater pipe on that, and if working by myself, pull the pipe down with a come along to break the rod nut loose (especially if it's been red loctite'd). Going back is easier, I mark the nut and rod end with a magic marker to make sure I get it back where it was pretty close. William in GA