Boomer 8N Loader won't lift unless bucket is curled back

[LD1]

To expand on what LD1 is saying the following criteria must be met.
1) The cylinder must be a single rod cylinder.
2) Both ends of the cylinder must be full of oil.
3) There is no external leakage path from the cylinder.

If these conditions are met then you can NOT retract this cylinder even with no seals on the piston. (NOTE: The cylinder will move slightly due to the oil compressing slightly.) The reason for this is the difference is the difference is volumetric area of the cylinder.

Example using a 3" bore 1 1/2" rod 18 inch stroke cylinder

3" bore x 18" stroke = 127.23 cubic inches volume cap end of the cylinder

1 1/2" diameter rod 18" long = 31. 8 cubic inches. rod volume

127.23 - 31. 8 = 95.43 cubic inches Rod end volume. You can NOT fit 127 cubic inches of oil into 95 .4 cubic inch space.

Like LD1 states: you can extend this cylinder since the smaller rod end volume will fit into the larger cap end volume.

Why people have a hard time grasping such a simple concept is mind boggling.


It amazes me the number of people who are so called expert hydraulic mechanics that I have met over the years that are so quick to claim cylinder seals are around fault for a system bleeding down. Then the people who are not familiar with hydraulics just regurgitate the bad info the "so called experts" told them, as if it were gospel.

I hope one day we can right this ship, at least on TBN anyway...

 

[PJ The Kid]

I finally understand this. The reason this test has worked for me in the past is because I not only had blown piston seals, but had cap seals leaking also ( I repack everything when I have it apart.) I had forgotten about the volume of the rod itself and was looking at it like moving a slug (piston) with nothing attached.

 

[LD1]

I finally understand this. The reason this test has worked for me in the past is because I not only had blown piston seals, but had cap seals leaking also ( I repack everything when I have it apart.) I had forgotten about the volume of the rod itself and was looking at it like moving a slug (piston) with nothing attached.

Glad you understand.

And yep, if a cap seal is leaking......thats the issue. Not the piston seals. (Not that the piston seals arent bad also).....But you could remove the piston seals. Cap the cylinder. And if you dont allow oil to escape it....it aint moving.

Most people dont take the time to actually test a cylinder. IE: their tractor loader bucket wont stay up and drifts down. Under faulty advise of many people they rebuild the cylinders without even testing them.....and wonder why it didnt fix the problem.

 

[100 td]

I stand corrected! And I need to read what was stated correctly! Funny thing, I was first thinking of a steering cylinder, then of my skidsteer with a broken rod and damaged piston, then I answered, then I immediately edited my reply and dug myself a HOLE!