welding a hydraulic cylinder

I strongly suggest that you do NOT make the repair for several reasons.

The most compelling reason would be the inside bore will distort after being welded thus would be needed line bored to restore too the correct bore diameter.

There is a reason why the tube split where it did. You first need to find the cause of the split before a method of repair (or if) can be applied.

If you still feel like you would like to save the old cylinder, I suggest you buy a book called: Advance Gunsmithing, W.F. Vickery, out of print but easy to find online with a google search.

Vickery explains advanced metal working in very simple terms thats very easy to learn from. He explains methods to accomplish very complicated tasks from extremely simple tooling that includes tempering and hardening metals for tubing under extreme pressures.

If after studying Vickery's book you would still like to make the repair, post again and we'll discuss which method would be best.

T_Bone

I never liked to leave my stuff in the weather cause it just wore it out fast but forgot to realize the added benefit of (protection from) the closed hydraulic circuit that you refer to which, as mentioned, can be catastrophic when heated.

Thanks for the thread,

Mark

If it is cast iron, cast iron is porous, and retains oil. The entrapped oil makes it difficult to weld.

If it can be thoroughly pre-heated (or even baked for a couple of hours in a hot oven), hopefully most of the oil will burn off, and make for a more successfull weld.

These cast iron cylinders have been known to crack from the expansion of the hydraulic oil in them when they sit unused in the HOT sun.

Unless having the "correct" old-style cylinder is important to you, I would replace it with a modern steel hydraulic cylinder. The cost ($50.00 to $100.00) probably wouldn't be much more than having the old one professionally welded.

www . surpluscenter . com

Only problem I'd see is distortion of the inner surface which would either keep the ram from functioning properly, or cut the seal on the ram.

Course if it only cuts the seal every year or so, and seals are cheap, what the heck. Would make a winter project.

Sickle bar mower isn't that heavy so you are not asking the cylinder to do that much. Even though your system has 2000 or so psig available, you don't necessarily use it. All you have to do is open the valve (spool) and let in enough fluid (pressure) to overcome the weight to be moved and that's that.

Say the task is to move 800 # and you have a 3" dia cylinder. It would only take 114 psig of hydraulic fluid to provide 800# of force acting against the load.

Mark