Allis Hydraulic Cylinder on Shredder

Looks to me that is a 2 way/push-pull cylinder be used as a one way, so that is a breather fitting where the second hose would go. The oil that is spraying out is coming from a leak within the cylinder.

So, I should put another hose on there and make it a two way cylinder?  What if I just put a plug in that hole?

You need a vent on a two way cylinder when using as one way.  The air in the other half of cylinder has to have some where to go.  You could put another hose on it and use as a two way but your cylinder will still have an internal leak.   The brush cutter is light weight so you could get along quite a while like that.

That is a home made vent. Put a 2nd hose on it and run it as a 2 way cylinder. That is a later AC cylinder made to run on a series 3 or 4 D17. I don't think they made an older high pressure in 2 way design. It they did I've never seen 1 in 70 years of being around AC's.

About the internal leak, does that mean that there is something inside the cylinder that allows the fluid to spray out of the relief value?  If I put another hose on the cylinder, will there still be a leak ?

More than likely, the seals on the piston are leaking, allowing oil to transfer from the bottom end of the cylinder, to the top end, where the shaft is located. Oil seeps past the seals, from the bottom end, cause that's were the pressure is. Once it gets into the top end, and the cylinder is lowered, now you have the piston pressing against the oil at the top end that has seeped by, and is now forced out the breather hole, as liquids can not be compressed, hence the spraying of oil. Personally if it was me, I would re-seal the cylinder, and then add the second hose.

How do you reseal the cylinder?  where can you get new seals?  Thanks, Dave

Are you referring to the hole the upper hose would go in as the "Relief valve"?  If that is the case you have leaky seals internally.  If there is another port you are referring to can you take a closer picture of it?  A normal cylinder only has two ports, a Gozin, and a Gozout!

The plug with the cotter pin is just another form of a vent. You're given explanation of the leak would support that style of vent. There are more sophisticated plugs with screens in them for a little cleaner operation but with the internal leakage that may soon plug and present the situation mentioned above. If you repair the cylinder I would personally choose to put the screen vent in at that time because the plug style you have now may have more of a tendency to inhale debris. 

There is no "relief valve" That is a vent, needed for one way operation.
 The ONLY way to fix it right, is to take the cylinder apart and put a new piston seal kit in it. Your oil is being pushed past the seal on the piston (#11 below) and once on the other side, HAS to have a place to go when you raise the cylinder.
 If you plug the hole, the cylinder will stop going up when the front side is full of oil.


Edited by CTuckerNWIL - 15 Oct 2019 at 11:28am

200Tom1 wrote: That is a home made vent. Put a 2nd hose on it and run it as a 2 way cylinder. That is a later AC cylinder made to run on a series 3 or 4 D17. I don't think they made an older high pressure in 2 way design. It they did I've never seen 1 in 70 years of being around AC's.

If you have a hydraulic repair shop near by, take your old parts and the cylinder and go visit them. It is most likely they will be able to match things up and get you the right parts. You should replace all the sealing parts of the cylinder while you have it apart. They will likely have the screened vent also.

Depending on the seals used it is not uncommon for a backup ring of some type to be used in the groove with the seal. Leather was used for seals and backup rings at times. There are some newer sealing options a good shop may have and suggest to you.

Boy, don't know how you could stretch a leather or cork backup ring over the end and into the groove, but guess that was done.  I'm planning to take the cylinder in to a hydraulic shop next week and see what they say.  Thanks for all the info and help.  Always a new adventure for me when trying to fix things.  Dave

Warmed up oil on the gas grill might help. Some pistons are made in 2 pieces so you can slide new seals right on the smaller diameter. I doubt many of these 'farm cylinders were built like that though.
 You will want to replace the wiper and seal on the rod while you have it apart, and check for any rusty areas on the rod. Things need to be clean and smooth, to keep a seal in working condition.
 I have a cylinder much like that one on my JD planter I bought a couple years back. When I got it hooked up and ready to go, I just removed the coupler from the end of the top hose (return pressure) and raised the planter up. That emptied out the oil on the top side of the piston. Then I put the coupler back on and wired the hose up out of the way. It works fine using it one way, because of all the air in the hose and cylinder can compress, and it could potentially draw air in on the down stroke if needed.



Edited by CTuckerNWIL - 21 Oct 2019 at 8:41am

$80 is less than a new cylinder. All the sealing parts were replaced and a proper vent installed as is the correct way to do it. It should go a long time for you now.