Hopefully I am posting this in the right area, since this issue can be related to almost any machine. If not, my apologies. I have a NH 675E backhoe. The extend-a-hoe cylinder is leaking so I am removing it to have it rebuilt. The bottom pin can out fine, its the top I am having trouble with. The cylinder itself moves freely on the pin when I lift the cylinder up and down (the few inches that I can move it) but it will not slide over, left to right. There looks to be about 1/4''-1/2'' of play between the cylinder and where the pin goes through the stick. However, the pin will not slide in either direction so I have concluded it is frozen in the stick, not the cylinder. I can see that the pin, where it is exposed is pitted, so I am assuming that is the reason the cylinder won't slide on the pin. I have SOAKED it in every type of lube, penetrating oil, etc that I have. There is no grease fitting on the pin or cylinder(because it doesn't move anyway, but I wish it had one anyway so this could have been avoided), I have tried to get a pipe wrench on the tiny bit of pin sticking out, I have tried 3 times to weld a bar to the pin to spin it, each time breaking the weld because there isn't much to weld to, and the pin being so tight. My most recent attempt was a contraption that hooks onto the stick, that I can put a bottle jack in, between the pin and the rig I built, and crank the hell out of it, against the pin. I could only find a 4 ton jack, my friend has my bigger one that I am going to get from him later. But I cranked the jack as hard as I could and have been wailing on my rig with a sledge hammer. Obviously, its not moving. The pin is hardened steel I believe, so I can't cut it with a sawzall, I can't get a grinder down in there, don't have enough room to hit it with the plasma cutter or torch. Im about to take the stick apart and rebuild the cylinder in there. Any advice appreciated.
For those not familiar with your machine post a photo of what you're up against might be a good idea.
2 options: 1. Heat the area around the bushings in the stick with a torch to expand them and release the corrosion then swing big hammer. 2. Heat the pin on both ends with a torch and then let cool, the expanding and contracting at different rates sometimes frees them up. (less effective).
I have heated the bushings several times, with the pressure on it as well. Not cherry red though, but I will try again and let them get extremely hot. I'll also try the second method too if the first fails. The only thing I don't want to do is keep hitting the pin so that the head mushrooms out and it won't slide though at all. UPDATE: Put a 12 ton bottle jack in the rig and cranked it until it started to bend my holding rig. I can still crank the jack, but its tough even with a 2 foot pry bar, so I would guess Im putting 8-10 tons on it. Went onto wailing on it, nothing again.
Stupid question...Are you sure there isn't still a keeper of some kind holding the pin in? With that much force and heat you should have freed it up by now. Worst case you can use the torch to blow the center out of each end of the pin as far back as possible. Once it cools it will relieve it some.
When you have heated the bushing good and hot, stick a candle or some other form of wax against the joint between the pin and the bushing while they are still good and hot. Often it will suck the wax in as it cools helping to ease things. No harm, no fowl if it doesn't help.
That is a good question because sometimes that happens but yes, I am sure. I have the service manual for the machine and I have checked that a while ago.
Exactly what I'd say. If you're not so comfortable with the torch you can drill the end of the pin, the center might be soft enough to drill with a cobalt bit, otherwise use a carbide bit sharpened a little more (masonry hammer drill bit), then either weld that hole up (to heat, then shrink it) or use the torch on your "pilot hole". You did remove something that held the pin in right? I've never seen a pin that didn't have some solid retainer.
Keep your jack on it with pressure and heat the bushings up where it's stuck, HOT
Ive had good luck shocking it with cold water or a block of ice on a stuck snow plow pin
Thank you all for the suggestions. I don't want to use the torch due to all the slag it will create and I won't be able to cut the pin without cutting part of the bushing and/or cylinder. Which don't be the end of the world but the pain in the *** position the pin is in will make for a job and a half trying to get the slag out.
I'm not sure if you understood the torch method. The intent is to use the torch to blow a hole in the end of each pin where they're binding in the bushings to cause them to heat up and then shrink when they cool. If you have a 2" pin with a 3" wide bushing at each end, then if you cut a hole close to 3" deep it will heat enough that the pin will shrink when it cools. If you wander a little with the torch the cold joint between the bushing and pin will keep the flame from eating the bushing for a little bit to help you. If you're really not comfortable doing that with a torch, then drilling and welding up the hole does the same thing.
My 2 cents take a grinder and grind around the out side of what is sticking out and then use the sledge no it. If you had a brass hammer to hold to hit aginst that would help.When it moves if you can push it back and grind it down if it has mushroomed. The sledge will put out maybe 4 times the force a 12 ton jack can.
I understand. I read the replies quickly on my cell phone. Thank you. I'll be doing this. Possibly, but when I have the jack pushing on the pin, and I'm taking a sledge to the back of the jack, that should be a whole lot of pressure....
Gouging rod or thermal lance, put a block under one of the jack legs to get the machine on a angle
I think the jack fluid is absorbing a lot of your hammer shock when you hit the jack.
Its basicly a shock absorber. Hiting something with a hammer is big jolt and is just what something that is stuck needs.
Try this web site, breath taking: http://www.broco-rankin.com/industrial/
They work really really well but they are really really expensive. Every time I have had to resort to the broco torch the pin has about fallen out once it was pierced
Uhh, guys, let's think back to high school physics. Q: What are some of the properties of a liquid? A: It is incompressible. A contained fluid with no air in it transfers force almost perfectly. A big difference in a jack and a shock absorber is that a liquid filled shock absorber has valves that release fluid slowly, and let the piston move. Actually, a "shock absorber" in a suspension system should be called a "motion damper", The springs or air bags actually move to absorb the shock, and the "shock absorber" actually slows the motion, and keeps down rebound. I have used the "hitting the jack" method with great success, usually to apply preload to something to keep it from just springing away from my 16 pound hammer. A 12 ton press force is not much at all in the heavy equipment world, though. A cheap shop press uses a 20-ton jack, and I can tell you there are many things it can't move. A small Porto-Power hollow cylinder like is commonly used to install pins and bushings is 30 tons, and there are many that require you to step up in size.
No compression at all? Guess there was a reason I wasn't a physicist. Now I wonder how much momentary pressure there is in a 12 ton jack already maxed out when hit by a 16 lb sledge. True enough also that 12 tons is not a lot of pressure in the press world.
That's a good question. It's beyond my physics and calculus skills. It brings up a good point though, I wonder if there is a relief valve in a jack, and what it is set at? I know a 16 lb hammer won't open it on a 20-ton jack, if it even has one.
Hydraulic fluid IS compressible, and the metal parts containing the fluid will expand under pressure spikes. For all practical purposes liquids are not compressible and since the amount they actually do compress is usually negligible, it's ignored most of the time. You do lose impact force through the jack and it's a good way to see up close and personal what happens when a hydraulic cylinder ruptures. Mind you it may be the last thing you ever see.
just a idea that no one has thought of... is it possible that the pin is bent? maybe why it wont come out... look real close to c if there is a roll pin type retainer in the end of that pin I am gonna say that you just don't have enough press power if you are sure you have no retainer holding it in.
I know, this will sound strange. but Ive driven out some large scraper and dozer pins with a jackhammer. weld a piece of angle to the pin boss to support the "punch" and give it a good rap.
Not strange at all. I have used a chipping hammer to remove steering wheels. The only difference from rrr's situation is that a steering wheel has to be supported or you would hammer the whole steering assembly. A picture of his pin would sure help give everyone a better idea of what he is doing.
Would love to see pictures, he said cyl slides on pin, what type of retainer did he remove from pin, is there a bolt on the inside? Does pin come out other direction, stepped?
liquid propane, take the regulator off the hose and freeze it then smack it. CAUSION!!!!!!!!!!!!!!! no open flames or heat on the work area things go boom if there is
Sure cut oxy lance. Blast out the Ctr of the pin, then we usually stuff the garden hose or the water filled fire extinguisher in the new found center hole. The shock from rapid cooling along with a slight shrinkage to to the big hole in the center they usually come out like butter after there fully cooled.
Sure would like an update on how the pin came out. Always good to hear what finally did or did not work.
This is probably too late but I've had the same problem with an earlier model. I took the stick apart and put it in a shop press. It took a lot of pressure to move the pin but it came out with a bang. Barring use of a press, the only other way I've seen it done is with a piercing lance. You have to be careful to keep the rod in the center of the pin or it will blow through the side and damage the pin bore on the cylinder. The shop press method isn't easy and takes time, but will work.
Sorry for not getting back to report. And thank you all for the advice. I wound up cutting the pin with a torch. I had just enough room to cut it, then beat both ends out. Turns out the new pin was just as tight, and i had to grind it down to get it in. :beatsme
Lets hope you dont need a "exothermal extraction" by a welder. Guy on youtube does some great videos on this......a very expensive welding option. Just type this into the Youtube window to see an amazingly stuck pin on a huge front end loader. No grease was ever put in these cylinder pins and they are STUCK big time. Before using the exothermic extraction technique he successfully removes the pins by welding a bolt to the pin and using a hydraulic compression jack to pop the pin out. Great video: John Deere Side Dump Bucket Repair Pt.1 https://youtu.be/xpEMCW5fV6Q
I would have worked on opening up the bore for the pin before grinding on the new pin, but that's just the way I think. As long as you keep it greased it should last many years. Grease after every use a you will flush out dirt and crap and have nice fresh grease in there for next day.