When you started up your mobile equipment earlier this spring and summer, you might have noticed it ran a bit sluggish. That’s because the summer season brings a lot of trouble to mobile equipment users in North America.

Most construction, farming or road maintenance equipment sits over the winter. One of the biggest problems of stagnant hydraulic machines relates to a quality of oil. Hydraulic oil is hygroscopic to a small degree, meaning that it absorbs and holds water in saturation. As the temperature drops in the winter, oil loses its ability to hold water in saturation. More and more water will free itself from the oil, causing oxidation, additive depletion, corrosion and reduced lubrication when the machine is started again for the first time in the spring or summer. With water and/or ice sitting in tiny pools all over your machine for months, damage and corrosion does occur.

When summer rolls around and you want to use your equipment for its desired function, you find seized hydraulic motors, leaking cylinders and seals blown out from freezing water droplets. So as we gear up for those cold winter months ahead, what can you do to prevent water from entering or damaging you hydraulic system? Well, removing saturated water from hydraulic oil is expensive, time consuming and—considering the rate at which it'll find its way back in—almost pointless. What you can do, however, is prevent as much water from entering the system to begin with.

The number one defense is putting your machine on liquid lockdown. Minimizing fluid connections, using only O-ring fittings and preventing pooling water anywhere near water intrusion points (like filler caps) would make for a good start. You can also use water absorbing filter elements. These can only remove free water, not saturated water, but they'll help if you know you're getting wet oil.

Keeping your hydraulic cylinders in good repair is another good idea, as water can enter through rotten rod wiper seals. Finally, you can install desiccant breather caps. These will pull moisture out of the air as it enters the reservoir during normal aspiration, preventing humidity from reaching the large volume of oil within.

As we prepare for what meteorologists are predicting to be another long, cold and snowy winter, it’s important that we do everything to keep ourselves—and our hydraulically powered equipment—warm and dry.

Josh Cosford is a certified fluid power hydraulic specialist with The Fluid Power House (Cambridge) Inc. Contact him at joshc@fluidpowerhouse.com or call (519)-624-7109.