In our previous post about the effects of heat on a fluid power system, we reflected on how heat can lead to problems in a hydraulic system, and ways to mitigate it.

With winter fast approaching here in Michigan, it’s important to begin considering the effects of the cold, as fluid systems are also not immune to the effects of lower temperatures. If you manage or maintain a fluid power system, it’s time to prepare your plan.

What Happens to a Fluid Power System in the Cold?

When exposed to cold temperatures, problems culminate in a hydraulic system. This often starts with an increase in oil viscosity and cavitation, possibly leading to damaged or inefficient machinery, and this leads to an increased chance of system failure.

Fortunately, it’s not difficult to prepare and winterize hydraulic systems by doing fluid checks and following through with consistent techniques.

Winterizing is vital to maintaining fluid power systems, and can help to prevent:

  • Damaging increases in viscosity
  • Trapped moisture in piping
  • Ice build-up
  • Cavitation and lack of lubrication
  • Loss of hydraulic pump and motor function
  • Damaged hydraulic hoses, seals, mountings, fittings, and other rubber components.

Even though the freezing point that causes hydraulic oil to gel and become unusable is -10 degrees Fahrenheit, a much lower threshold than the ambient freezing point of 32 degrees Fahrenheit, fluid can still increase in viscosity before gelling, causing performance issues with hydraulic pumps and motors.

Taking a few simple measures to winterize fluid systems can save lots of complex repairs and replacements, as we’ve outlined below. Making viscosity considerations and fluid checks, then preparing equipment before use, and finally by storing fluids, equipment, and components properly, hydraulic systems can continue running smoothly throughout winter months.

Viscosity & Fluid Checks

Viscosity should be the first consideration when preparing fluid power systems for the cold.

Using fluid with the right viscosity for the application can help to protect equipment from friction, abrasion, and adhesive wear rise.

The wrong viscosity can have the opposite effect. In particular, high oil viscosity can lead to starved pumps, cavitation, and lack of lubrication. Lower temperatures cause hydraulic fluid to increase to a higher viscosity. Close attention should be placed on grade, pour point (and added depressants), as well as the viscosity index (VI) of fluids.

Most hydraulic parts made of steel or iron may not be affected by temperature. However, friction and wear, particularly on seal material, can occur due to a higher viscosity in fluids.

To prepare fluid systems, choose hydraulic fluids with a low VI, which is measured when subjected to change in temperature. The higher the viscosity index, the higher the resistance to change in viscosity.

Consider checking VI requirements and fluid levels within hydraulic equipment prior to starting. If any fluid is too thick to drip off the end of a dipstick, it is too viscous to function properly, especially in the cold. It is also wise to check fluid levels before each use, and refill after each use.

Equipment Prep

Along with making sure fluid viscosity is appropriate for the expected temperatures, it’s important to do a proper warm-up of equipment to prepare fluid systems in the cold months.

For best cold weather performance, run the hydraulic pump or use a hydraulic tank heater before operation. It is best to check and ensure the hydraulic oil temperature is reading 150 degrees Fahrenheit prior to running to ensure proper lubrication throughout the system.

Proper Storage

Keeping equipment in a closed facility is the most effective way to shelter the exterior of machinery, but also vital to keeping fluid systems protected.

Internal fluids could freeze if machinery is exposed to sub-zero temperatures, so make a plan to store even heavily used equipment.

Further, make sure to have a space to store all hydraulic oils and fluids at room temperature to protect viscosity.

Other tips for winter storage that protect fluid power systems:

  • Remove any attachment parts and store them separately
  • Inspect for cracks and tears on rubber components, and keep spare seals, rubber mounts, and fittings in closed storage
  • If there are any abrasions along the hydraulic hoses, tires or belts, replace them immediately
  • Protective wraps and sleeves can be stored and used to protect hoses and components from winter damage.

Drops in temperature do not have to mean damage or hydraulic system failures.

Prevention is as easy as following the steps above – make solid viscosity choices and fill up, use a quick warm-up technique, provide the proper storage for equipment, and you’ll reap the rewards of having maintained your system well through the winter and into the springtime.

Cory Gilbert
Cory Gilbert

With a personal goal of taking care of the customer at all costs, CEO Cory Gilbert has been a driving force behind the high level of customer satisfaction at Hydraulic Parts Source since 2009. Cory has a “whatever it takes” attitude and helps maintain a customer service team that is accountable, honest, efficient, and hard-working. One of the first things you’ll learn about Cory in his professional life is his belief that “customer relationships are everything.”

Cory is a graduate of Alma College with a degree in Finance and Marketing. Outside of work, he enjoys spending time with friends and family. He is a sports fan who also enjoys golfing in his free time.