hydraulic clyinder questions

I was told that a person can replace packing with O-rings.. I have torn down one of my clyinders ( bad leak) and the rod has some pits in it , and a neighbor came by and saw what I was doing and sugested putting O-rings instead of packing .... What do you think? Can it be done? Thanks in advance.. Larry

If the rod is pitted then you will have to replace the whole thing Good Luck.
Walt

Wash the pits out with thinner and a tooth brush making sure you get all oil cleaned off then fill the pits with epoxy or JB weld. Let it dry over nite and smooth it down with emory cloth. That will take care any oil that was leeking through the pits. I should think o-rings would work in place of packing but why not replace with correct packing?

It sounds like your talking about rod packing. If the packing gland calls for cup packing, it's doubtful you will be able to replace it with an 'O' ring. Why wouldn't you use the proper packing? Even if you could find an "o" ring that would come close to fitting, it probably wouldn't last very long. rw

There are some good hyd shops around that can clean up or
replace that ram for you

No, rod packing can not be replaced with O-rings. The rod packing, typically, is going to be a lip type seal. The most common type on the older machines was a multi piece Chevron type V packing and the "newer" stuff usually uses a single "polypack" type. Both use both the interference fit of the lip as well as the hydraulic pressure in the cylinder to force the lip against the rod causing it to seal. An O-ring has no way to provide the type of high pressure seal needed in this type of application.

As for the pits on the rod I can only say this without actually seeing it. I"ve seen new cylinders get dented, scratched, etc on their firs day on the job and have also seen cylinders with numerous pist, scratches, etc run alot of years with no real problems. True your gonna get "premature" wear on the seal and a bit of leakage but unless there is a massive amount of deep pits, scores, etc they probably aren"t worth worrying about. The worst thing you can have on a cylinder is a scratch running length wise of the rod or running around the circumference of the rod. The length wise one will let fluid run right under the seal and the other will allow the lip of the seal to drop into it so the movement of the rod pull"s at it, and eventually cuts it.

Like I said a number of small pits spread out over the length of the rod will allow minor amount of leakage over time and you won"t get the "full life" out of the seal but beyond that there"s no reason you can"t use a lightly pitted rod. If you want absolutely zero leakage then a new rod is your only choice.

Dont shoot me PLEASE, I made a mistake saying they are pits ..... They are more like small chips off the chrome down to the metal...Maybe 8 or 10 little chips.. Dont know if that makes a differance or not.. Thanks for the input guys... Larry

TAKE SOME OF THE WIFES SCOTCH BRITE 4 SCUBBING DISHES AND SMOOTH OUT THE RUOGH SPOTS SO THERE R NO SHARP EDGES THEN REPLACE PACKING, O-RING WILL NOT REPLACE PACKING WHAT SIZE ROD ARE U TALKING ABOUT AND HOW MANY V-S I HAVE OR CAN GET EVERY THING U NEED, IS THE PACKING GLAND WORE OUT ?? SHOULD BE 2-3 THOUSANDS OF AN INCH OVER ROD DIAM.
LINDBERG SEVICE TECH 4 LAST 15 YRS ,[email protected]

Only one cure to have the rods re-chromed and then ground that will usually cost more than a new one.
Walt

Some of my hydraulic cylinders and most of the pistons I've seen do use O rings for seals, but those O rings are backed up with special support rings on both sides.

Look at Baum Hydraulics for cylinder seal parts.

Gerald J.

If that's all that's wrong with the rods put in new packing and run it.