Help .... Frozen hydraulic pivot pin

   / Help .... Frozen hydraulic pivot pin
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Navvet

Navvet

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I just realized some clarification may be needed here;

1) There is no production work being impacted here. I buy old equipment that I have a specific need for, fix it up and then sell it after I'm done. In this case, this is a Marklift boom lift I plan on using to add a garage onto my house (primarily lifting and setting trusses). As with most things I buy, I got this (through a reputable dealer) for a great price (less than $5K). I'll fix it and use it for a year or two and then sell it.

2) You can see in the picture below, most of the pins run through 3/4" steel plate. This one runs through a pair of 5" by 2" 3/16" square tubes. The sleeves are mounted roughly in the middle of an 8' span so I am getting a lot of flex anytime I hit the pin. The tubing and the sleeve shown in the picture are at the end of the span and just shown for reference. I have concerns about using too much heat and weakening the square tubing.


IMG_20220101_112331493.jpg
 
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   / Help .... Frozen hydraulic pivot pin #12  

xrjohndeere

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Mo
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2021 Kubota L4060 HST
I have a 1.5" hydraulic cylinder pivot pin that is seized and will not come out. It moves easily on the cylinder end but is frozen to the sleeves in the square channel on either side.

The pin was held in the sleeves with vertical drift pins but over the last 30 years moisture has gotten in them and rusted the pin to the sleeves.

All the others I have removed came out with a few taps from a hammer and a 1" steel punch.

I tried welding a 1/2" bolt to the end and turning it out, didn't budge.

I have used heat (Oxy / acetylene torch), various penetrating oils (WD, PB, etc), no go.

I made the jig in the pictures with 5" channel and used a 10 ton hydraulic ram, no go.

I have just about run out of ideas, I am thinking about cutting the cylinder out with a hack saw blade and then working on either side's sleeves individually, but I don't want to take a chance ruining the cylinder.

Any Ideas ???

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Endothermic cutting rods. They will burn a hole straight through the pin. When it cools it will drop out. Do a search on the net. It’s very fast and easy to remove a pin. Find a heavy equipment maintenance company in your area and they will probably have the tool and come to your place to cut it out.
 
   / Help .... Frozen hydraulic pivot pin #13  

MinnesotaEric

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My suggestion as a mechanic:

Harbor Freight’s Chief air hammer for $130 is the same thing as the $500 Mac Tools air hammer with a cheaper trigger. Buy it.

With that air hammer heat the joint up with a acetylene torch and give it a whack with the airline pressure set at 175psi.

If that doesn’t work, you’re going to need to lance it out.

 
   / Help .... Frozen hydraulic pivot pin #14  

jaxs

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Just an update, we have been able to move the pin a 16th to an 8th of an inch using the jig and a sledge but it just won't go through. Too much flex in the square tubing to allow me to push with full pressure. Next step is using the hacksaw blade to cut the pin and drop the cylinder out of the way and then just work on each sleeve independently.



I am keeping the "Pro" as a last option. I'm retired, stubborn, and cheap and don't want to admit defeat yet.
I'm also retired,stubborn,cheap and don't like admitting defeat but I subscribe to what Greek and Roman doctors said. "First do no harm". And the modern Hippocratic Oath which in part say's "I will not be ashamed to say "I know not," nor will I fail to call in my colleagues when the skills of another are needed for a patient's recovery."
When I worked for a living I had a sign on the wall of my shop which read;
Shop labor $20 per hour
Shop labor if you watch $30
Shop labor if you help $40
Shop labor if you fixed it first $50

Odds are not more than 2 people here can successfully do what they suggested you do. At any rate good luck and let us know how it come's out.
 
   / Help .... Frozen hydraulic pivot pin #15  

fishdrivel

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Kubota B2910
That mag drill would be nice. I was thinking about rigging my benchtop drill press over the arm. May try that if the sawzall doesn't work out...
The key to the magdrill is you can keep it centered.

I'm worried that all the sledgehammer work has mushroomed the pin and hardened it
 
   / Help .... Frozen hydraulic pivot pin
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Navvet

Navvet

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Mahindra 4025 Bobcat S185 John Deere X495 John Deere 6x4 Gator
I'm worried that all the sledgehammer work has mushroomed the pin and hardened it

I'm concerned about the ends also, I think it's time to cut the pin in the center and push it out either side.

Anyone know a good source for a 1.5" X 12" pivot pin ???
 
   / Help .... Frozen hydraulic pivot pin #17  

jaxs

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It has been some years since I sourced material such as flats,bars and rounds but I've bought it in stock leingths which could be cut to size. I had the best luck with specialty bearing distributors. Problem is these things might need to be so hard that cutting take's special tools.
 
   / Help .... Frozen hydraulic pivot pin #18  

BeezFun

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2) You can see in the picture below, most of the pins run through 3/4" steel plate. This one runs through a pair of 5" by 2" 3/16" square tubes. The sleeves are mounted roughly in the middle of an 8' span so I am getting a lot of flex anytime I hit the pin. The tubing and the sleeve shown in the picture are at the end of the span and just shown for reference. I have concerns about using too much heat and weakening the square tubing.
I have a lift, very similar design except you have the benefit of a grease fitting. It looks like there is a safety roll pin still in the shoulder that goes through that pin, or is that part of the grease fitting? I'm sure you're smart enough to notice a safety pin, but I can't figure out what I'm looking at.
 
   / Help .... Frozen hydraulic pivot pin
  • Thread Starter
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Navvet

Navvet

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Mahindra 4025 Bobcat S185 John Deere X495 John Deere 6x4 Gator
I have a lift, very similar design except you have the benefit of a grease fitting. It looks like there is a safety roll pin still in the shoulder that goes through that pin, or is that part of the grease fitting? I'm sure you're smart enough to notice a safety pin, but I can't figure out what I'm looking at.
The pin and sleeve you are looking at (with the drift pin and grease fitting) is one of the ends of the arms. What I am working on is mid span of that arm, where the hydraulic cylinder connects. I am removing the hydraulic cylinder to rebuild it with new seals. I added that picture to show how the arms are actually pretty light weight metal compares to the 3/4" steel they attach to.

All around this is a heavy, well built machine weighing in at close to 11,000lbs. It's amazing that a 29hp engine driving a hydraulic pump will move and operate it.
 
   / Help .... Frozen hydraulic pivot pin #20  

BeezFun

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The pin and sleeve you are looking at (with the drift pin and grease fitting) is one of the ends of the arms. What I am working on is mid span of that arm, where the hydraulic cylinder connects. I am removing the hydraulic cylinder to rebuild it with new seals. I added that picture to show how the arms are actually pretty light weight metal compares to the 3/4" steel they attach to.

All around this is a heavy, well built machine weighing in at close to 11,000lbs. It's amazing that a 29hp engine driving a hydraulic pump will move and operate it.
OK I get it. As long as you can get the cap end free, could you rebuild the cylinder without removing the rod end from the machine?
 
 
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