Learned lesson on disassembly of cylinder

racerboy832 · Mar 30, 2011

A friend brought in a big old stabilizer cylinder off a backhoe. This would just blast oil out of the seals as soon as you hit the lever. We tried a spanner tool and it would not budge, then thought it was reverse thread, no luck, next was a chain wrench, no luck, chain wrench with a 3 foot bar, still no luck. Broke out the torch and heated it up, would not move at all. The fabricator says I have one trick, it will either work or tear it apart. He brings it over to his huge 4 jaw lathe, Clamps the end that unscrews into the jaws, Puts a pipe through the fixed end. Clicks the on switch in Low gear and it unscrews like it was hand tight. I learned a neat lesson and it only cost me a cup of coffee.

KWentling · Mar 31, 2011

racerboy832 said:
A friend brought in a big old stabilizer cylinder off a backhoe. This would just blast oil out of the seals as soon as you hit the lever. We tried a spanner tool and it would not budge, then thought it was reverse thread, no luck, next was a chain wrench, no luck, chain wrench with a 3 foot bar, still no luck. Broke out the torch and heated it up, would not move at all. The fabricator says I have one trick, it will either work or tear it apart. He brings it over to his huge 4 jaw lathe, Clamps the end that unscrews into the jaws, Puts a pipe through the fixed end. Clicks the on switch in Low gear and it unscrews like it was hand tight. I learned a neat lesson and it only cost me a cup of coffee.

A nearby coal mine has (had ?) about a 24" Summit lathe that they did something similiar with. It got the job done, but put a significant kink in the ways. One of their machinists was complaining he was having to adjust the tailstock all the time and couldn't cut anything without taper. Since I do the maintenance and repair on our equipment, they sent me over to see what was wrong with their lathe. I set up Brunsun optics and shot through the spindle and found how bad it was. I don't remember the numbers now, but it basically junked the machine. Was beyond scraping or regrinding to salvage. Pretty expensive wrench they got.

Kim

Rocwin · Mar 31, 2011

We would never give the mechanics here access to a lathe to remove the gland from a cylinder. Using methods like this makes people stop thinking about why the cylinder isn't coming apart because they can just use brute force the minute they get stuck. It wouldn't be too long before you get several "oops" moments when they overlooked a lock wire or well hidden set screw and do some damage.

wdchyd · Mar 31, 2011

Glad it worked out for you racerboy, but I have to side with Rocwin & KW......this can be BIG trouble if it doesn't just come apart.....

Many parts have to be remade if proper procedures are not followed by doing things carefully.......if done carefully you have plenty of time to heat/cool and decide what to cut or machine before it's all junk.....I've had many jobs come in that took more work/money to fix messes from poor dis-assembly than if it had just been dropped off for us to do the work.......:confused2:

At work we take pride in our work not to just put the boots to it......using a big lathe doesn't give you the finesse of a cylinder tear/down bench......ours can go over 30,000 ft/lbs without any damage to the machine and it gives readings of torque.....

Remember this: "If it doesn't come apart right, It'll never go back together right"

Ford tractor · Apr 1, 2011

wdchyd said:
Remember this: "If it doesn't come apart right, It'll never go back together right"

Truer words were never spoken!

The real "trick" on cylinders is to loosen the gland nut while the cylinder is still mounted. A brass brush to get crud out of the threads is also smart and using a high quality penetrant. NOT WD-40! And if you can give the penetrant 24-48 hours that's better.

wdchyd · Apr 2, 2011

This reminds me when another repair shop(truck garage) brought in a cyl for a simple repack but the alum gland was heated so hot you could see the alum was dripping out of the cyl barrel....."New Cylinder"

and two weeks ago a customer only wanted a seal kit but the cyl was not apart yet.....then he left because we would not take it apart while he waited .......fast forward to last week and the "Volvo Dealer" brought in same cyl to have a new rod and Piston head custom made up (parts no longer available from Volvo)....the customer and his mechanically inclined neighbor forgot to remove a hidden set screw under the wear band and stripped the rod and piston head but managed to get about 4 turns on it......OUCH..!!......we ended up getting the job to fix their goof-up and they paid a middleman to boot...

Although mistakes can happen, that customer would have saved money if he just left it for us to take apart.....

racerboy832 · Apr 4, 2011

Before I knew too much about cylinders, I took one over from a customer for his log splitter. Well week later he picked it up , $300 bill to rebuild. Then about month later I brought one over for another friend who knew the guys and what's actually in it. $75 total. I have no problem bringing cylinders into having them fixed but when there is about $30 in parts that wear out I sure can't see paying 270 in labor. If I had known it was gunna be $300 I'd bought a new one.

wdchyd · Apr 4, 2011

Unfortunately it is a buyer beware syndrome for hyd repairs.....

Likely the $75. repair was either a "Good ole boys discount" or the $300. repair was a "How much money you got boy, Invoice"

I'm sure they weren't getting rich on the $75. bill......

Rocwin · Apr 4, 2011

There is another thing to consider when choosing to buy or rebuild cylinders. There are a huge number of cheap imported cylinders (or just badly made cylinders), but they will leak and won't last. We take apart new cylinders all the time and these things are built out of tolerance, you are either going to be endlessly buying new cylinders or endlessly throwing in cheap sealkits. Sometimes spending $300 for someone to take apart the cylinder, measure, machine, hone and reassemble with good seals (not junky polypaks) will last you several new cylinders, of course this only applies for someone doing the job right and not shafting you.

KWentling · Apr 4, 2011

A basic rebuild may include more than just changing seals. Some of the cylinders we rebuild get the barrel honed and the rod polished. More involved repairs may have threads repaired, rod and barrel ends welded and machined, rods re-chromed, new rods made, re-tubes, piston and gland repairs or new parts made, etc. $300 is pretty steep for just changing seals.

Kim