Why is your Hydraulic Cylinder Leaking? (Part One – That’s a Wiper, not a Seal)

A hydraulic cylinder could be leaking for all kinds of reasons. Let’s face facts, the things malfunction all the time, but how could we blame the cylinders for breaking every now and again? Hydraulic systems are complex; to function correctly, they must make use of many moving parts to complete repetitive work that is both precise and constant. Any working machine would fail from time to time given those same mechanical demands. So, why might your cylinder be leaking? What are some things to be on the lookout for that might be the cause of your leak? Well…

It could be you’ve been replacing the wiper, not the seal

You’d be surprised how common this mistake is. It’s easy to assume that the first seal looking object in the cylinder is actually the seal. Look at this picture – doesn’t it look like a seal?

hydraulic cylinder

Well, it isn’t. Pictured above is a wiper – the part of a cylinder responsible for keeping sand, dirt, and other debris out of the cylinder. If you want to know how a wiper keeps out all of that debris, go here and read up on it. We are going to shift gears towards why a wiper isn’t a seal. It’s simple actually.

Seal keep stuff in, not keep stuff out

You don’t believe me? Go ahead and click that title. Nowhere in that information does it mention keeping stuff out of the cylinder. Seals specifically work to keep all of the fluid and gas inside the cylinder. They are inherently concerned with pressure control. Take a look at this image:

IMAG0602

Notice how the seals in this photo have the ability to press down onto the cylinder, as opposed to sitting on top of the cylinder like a wiper does. Pressing the seals down over the cylinder creates a pressure lock that keeps fluid and gas inside.

Now, don’t get me wrong. It’s important to replace both the wipers and the seals on a cylinder to keep it in working order, but replacing the wiper thinking it’s a seal will cause you to neglect the seal altogether. That will lead to cylinder failure. Knowing the difference between the two will definitely extend the life of any cylinder you maintain.

And, of course, if a cylinder repair is beyond your expertise – give us a call. We are professionals, we can certainly fix any that happens to be wrong with your cylinder. You can count on that.