Cat 120 excavator project. Heated up the track rail and pounded out the pin that joins the track rails together. Then replaced the idler. Now need to reassemble the track rail. I plan on using dry ice to shrink the pin and hopefully place it inside the track rail with out hitting it with sledge hammer. Never used dry ice before. Question #1: How long to I need to have the around 1.125 inch thick pin in the dry ice to shrink it? Question #2: Do I need to heat up the track rail links, before placing the shrunk by dry iced pin into the chain rail openings? Question #3: Just how straight do the holes of the two chain rail sections have to line up, I got them pretty close have not been able to get them right on straight and I did grind off the edge of one side of the pin to help it go into the openings. Question #4: If I have to, can I pound on the frozen pin to pound it into the chain rail sections, I would not think the pin would break. What could go wrong? Thank you for your replies, much appreciated, this is a wonderful site for information.
I used Dry Ice to freeze bushings for a backhoe. It helped but wasn't the easy job I thought it to be. Bushing stopped before final position. Had to force it into place for consideration... Dry ice is -109 F Liquid N2 is -320 F Just putting it on dry ice will take an hour for it to cool through. I suggest dry ice in acetone to cover the pin Once the pin contacts the track it will rapidly expand. So if the holes don't line up perfectly so the pin can fall into place, you'll have to force it in. Maybe, a slip fit diameter dummy pin to line up the links, to be pushed out by the frozen pin. I've estimate you'll get about 0.002 " shrinkage with dry ice from 60 degrees F
second all of the above. Liquid Nitrogen will do a faster job and get you more to work with, and that dummy pin idea is a good one
Another vote for liquid cold. If the farmers around your area carry out artifical insemination liquid nitrogen and a Dewar flask to carry it should be available because that's what they use to freeze the sperm for AI.
Did you remove a master pin or a regular pin? Did you remove the pad when you removed the pin? Just how hot did you get the link? The holes have to be lined up to get a pin in. If you heated the link up hot enough to turn red you have shrunk the hole and or bent the link. Trying to cold shrink small pins is usually a waste of time and money. Put the link together on the sprocket it helps line up the holes. If you drive pins wear double eye protection. Bob
If they are Cat tracks with an old Cat master pin, you will have to use a hammer no matter what. You don't mention which series of excavator you have. You must have an early A model unit to have a press fit master pin. As I recall most of the Cat excavators used a T headed slip fit master pin that was held in by a cotter pin. Check the diameters of both the pin and the link bores. Cat makes their press fits especially tight, something like .005 to .007 inch. Your pin will not shrink that much in either nitrogen or dry ice. If using either, you will have to work fast as the heat transfer back into the pin is a matter of a minute or less and liquid nitrogen is maybe three minutes. Once the temps of both the link bore and the pin equalize, the pin will seize in place and the only way to move it then is with a track press. Lining up the bores on old tracks is problematic at best. I always burn a hole in a press fit master pin and buy a new one. I'll use the old one as a dummy to line the bores up as best as possible. You will need to put a little resistance against the dummy and hitting the new pin will cause the dummy to shoot out the other end. I usually use the dummy and then move the machine so the link is held under the front roller flanges if possible. That way the opposite side link won't try to spread when I pound the new master pin in. Looking at the responses you see here should clue you in that there are many ways to do the job. The key is to stay flexible because at times any of them will work and then again at times none of them will work. Hopefully you don't have to try them all. Good Luck
Why not rent a track pin press and eliminate the guesswork of doing it another way? Or, hire a party with one that can do the job for you? I've found sometimes it is much easier or less headache to sublet some things I don't have the specialized tools for. Basically, hard to beat someone at their own game, (FWIW).
Rent a track press????????
Well we put the old pin back into the track. Used dry ice, had the pin in the dry ice for over 2 hours, but the cold pin would not even go into the track rail hole. Then heated the track with a torch, and yes the rail got red in a few places, when taking the the pin out and putting it back in. Interesting that it might have shrunk the opening. So I put the pin up to the hole and pounded it into the track rail, once it got started it went right in, it ended up about 1/8 inch out side the other side of the track rail compared to the other pins. Tried pounding it back in to even up but no go, should not hurt anything. Was it worth the $500 saved that the local Cat dealer wanted for the labor to switch out the bad idler, I don't know, it was interesting the whole operation, do not know if i will do it again, will have to think about that if the need arises again. A great big thank you for all the comments.
I've done hundreds of track pins on most makes of dozers and excavators and never had a problem with heating a link red hot. It doesn't shrink the opening a bit until the pin and link equalize in temperature. Once they cool they will lock in tight.
Next time leave the track pinned. Then let out the grease in the slack adjuster and just slip the track off whole.
No, not a track press but a portable track pin press. There is a place around here you can do exactly that.
I'm well aware of portable track pin presses. I've never known of anyone that rented one out to anyone. I've had friends that would have let me use one maybe. They are too big and the potential for damage to the press, the fixtures and brackets or danger to the user precludes anyone but an employee of the owner using one. At least in this three state area.
yes every one I have seen comes on a service truck with a crane.
The one I've seen for rent is built up from several pieces and really isn't that heavy piece by piece, but there are about 10 pieces parts to set it up. I'd imagine it's a nutbuster if moved when all together, but the weight of it rests upon the track shoes so the operator doesn't bear much weight. I've "borrowed" it as I know a few guys working there. Slow to use but sure as hell beats a sledgehammer and doesn't damage anything.
Can't tell you if this is the exact same or not but very similar:
I can't see how that is 200 tons as the one I used at the Komatsu dealer had four rods and the cylinder was double the size of that one. The press plate was two inches thick. I used it for PC1000 excavators and D455 tracks. That one is an odd piece of tooling in Asia. The standard 100 ton units are C frame presses and weigh a couple of hundred pounds. They are meant to be hung from a crane and a box comes with them that has all the bushings and pin drivers for each size of track. Press and box of fittings are probably close to or over 300 pounds. I've seen steel splinters shave off and go flying like bomb shrapnel when things weren't lined up just perfect.
Can't tell you on that one myself. I think it's closer to 100 ton and they erred by the 200000 psi of force calling it "tons". A 10K psi pump driving a 5" piston is just shy of 100 ton of force. Seen that a lot on winches as far as first layer wrap of line pull. Being metric, it could be a bit larger piston area which would increase the force. The one I borrowed was not chinese branded but I cannot remember the name. It had no problem pushing pins out of a 316 Caterpillar excavator for me. Only time I've ever seen it used and it sure took some time to set up and align. It did however work, and work well if not in a production environment.
I think I'd be on the other side of the service truck while the Chi Com 200 ton death press does it's thing lol.
Thanks for this useful infomation
The old Cat track pin press used 2 rods and a plate . Power was the ram for the final drive press set, I think 70 ton. It was assembled on the track without a hoist like the sprocket press. Bob
Think about what you just said ,if you heat a link hot enough to drive a pin out when the link cools the hole will be smaller. That's a fact I use this to shrink slightly oversize bores. Most people heat a lick way too hot and they usually crack under heavy use and or the pin comes loose. I own 2 pin presses a50 & a100 ton and I have been driving track pins for 50 + years. Bob
I’m sorry,but…..dare I ask how you know???? No,hang on,on second thoughts,I’d be better off not knowing
This case would not work, the chain rail has a few 100 hours on hour meter so no slack in chain, thank you for the good comment it is a good Idea for some machine that has slack in chain rail.