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Pitting on Hydraulic Cylinder

A 10 cm dia. hydraulic cylinder on an industrial truck has some eroded areas 1

- 8 mm across and maybe 0.3 mm deep. The pitted areas might not leak a lot by themselves but they may be rough enough to have worn out the old seals which are leaking a lot -- no matter the position of the cylinder, it slides down. The pressure is OK on the inlet to the single acting cylinder.

What could have caused the pitting?

How long would it take for new seals to wear out on the old cylinder? Is there any alternative to rechroming the cylinder? The lift isn't used a whole lot.

Bret Cahill

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BretCahill
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Water in the fluid? ________________________________________________________ Ed Ruf Lifetime AMA# 344007 ( snipped-for-privacy@EdwardG.Ruf.com)

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Ed Ruf

Dear BrettCahill:

What is the purpose of the cylinder? What is its pressure cycle like? (pressure, duration, pressure swings) When it is running, how long does it run? What is the maximum speed of the cylinder? What is the filtration on the system? Is there a pattern to the pits?

There are only a few causes of pitting in hydraulic systems. Bad seals may even have been the initial cause of the pitting.

Depending on how your define "wear out", it could be only a few hundred cycles...

Not that I am aware of.

David A. Smith

Reply to
N:dlzc D:aol T:com (dlzc)

Several years ago we had air cylinders located above a run out table in a hot strip mill. Although the carbon steel shafts were chrome plated they pitted and lifted the chrome plating. It was explained to me that chrome plating is NOT a sealed coating, but is like "tree leaves" covering the surface and allows moisture to get beneath. We replaced the shafts with stainless steel (CRES) and no longer had any problems. Chrome plating provides a hard, smooth wear surface for the seal only and not as protection against pitting.

Jim Y

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Jim Y

I worked at some shoe string operation for awhile and we always had water and chemicals mixed in the hydraulic fluid. If you said anything about the milky white fluid emulsion they looked at you funny.

The cylinders were always nice and shiny.

Bret Cahill

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BretCahill

The packing was attached to the bottom of the ram. In other words, the sealing surface was the inside of the stationary outer cylinder. The exposed pitted areas had nothing to do with it.

Bret Cahill

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BretCahill

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