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Broke a hydraulic cylinder rod on my Bobcat

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OldMachinist

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I was digging a low water creek crossing last week and there was tree in the way. I dug all around the trunk and went to push it over like I've done many times before. Caught the bucket off center on a fork of the tree and broke a lift cylinder rod.

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Here's what it looked like off of the machine.

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Ordered a piece of chrome plated hardened 4140 for the new rod and made a new screw on rod end while I waited for it to come in.

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New parts

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All back together and better than new. New rod end got some Loctite 271 when I assembled it. It will have to be heated to 250F for it to come apart.

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Rbeckett

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Goood lookin repair Don. Bet it saved a bunch of hard earned cash too. Where did you get the 4140 chromed rod from? That stuff is usually pretty hard to find other than at a hydraulic store and they want top dollar for a small piece. That rod is like 30 inches or more so I know it wasn't cheap. And Bobcat probably only sells the complete cylinder or a packing kit and if you need anything else you gotta buy the whole cylinder to get what you need. The red Loctite definitely is a great idea too. We used to use the green when we rebuilt large (8 In and larger) cylinders to keep the gland nuts from backing off when they got heated up from being run all day. After several hours of hard digging the oil gets pretty close to 250 so we used green because it is semi permanent. Have to heat it to red hot to break it loose later on.

Bob
 

fastback

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Very nice looking job on the piston repair. I am also wondering where you got the stock. Definitely the way to go.
 

OldMachinist

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McMaster Carr sells the chrome plated hardened 4140 rod. It's not cheap but you can't beat the next day delivery I get.


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Bobcat gets around $800 for a new cylinder. I didn't even call them for price on just the rod.

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stevecmo

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Don,

Very nice job! When you live in the country and depend on your machinery it makes you glad you have a lathe and mill. That's a good clean fix that should last forever.......well at least until next time. :))

Steve
 

raross61

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Very surprised that Bobcat is still using, the SAE American sized rods! Your machine looks pretty current model, and from being in the heavy equipment business, for 25 + years, almost all our rods are now METRIC! BTW great looking repair job!
Bob in Oregon
 

raross61

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Very surprised that Bobcat is still using, the SAE American sized rods! Your machine looks pretty current model, and from being in the heavy equipment business, for 25 + years, almost all our rods are now METRIC! BTW great looking repair job!
Bob in Oregon

One more thing you have to get a laugh out of, if I had 1$ for every time some people try this I would be rich! They just bend the cylinder rod, and don’t break it, and then they looked it over, and decided if they suck it back in, it might straighten it! Now I am serious here, seen it many times it never works, but what it does do is pull metal off the pistons and dump it in the machine hydraulic tank, and spool valves! And with the hydrostatic drives, 75% of the time if you run it even a short length of time, you usually need 2 new drive motors, and new pumps, and maybe a valve assy., spools are all honed to fit per valve, and the OEM manufactures do not sell spools separate, from the entire valve assy.!
Take Care Bob in Oregon
 

Rbeckett

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Darn!!! I have never seen that in the Mc Master catalog online. They are kind of clunky so if you don't use the right name or description you will never find it. They got more stuff than carter has liver pills, just figuring out what they call it is the hard part. That was a great find and a better save, 800 bucks for a cylinder would sink me for a long time. It still wasn't all that cheap, but it was way less than the 800 and probably faster too.

Bob
 
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