What is Hydraulic Oil?

Hydraulic systems are widely recognized as crucial components in heavy machinery, especially aircraft. These systems are used to operate some of the most critical parts on airplanes, such as the brakes, flaps, flight control, and landing gear. In addition, hydraulics can deliver exact amounts of pressure and are more reliable than other options such as a pneumatic system. While hydraulic systems as a whole are very complex and made up of many components, one of the most important and often overlooked elements is hydraulic oil. This blog will discuss the function and different components of hydraulic oil.

Hydraulic oil is a fluid used to transfer power to various systems, dissipate the high amount of heat given off by these systems, and carry away unnecessary by-products such as water and debris. While different types of oil are used in hydraulics, they generally need to have specific physical properties such as low compressibility, resistance to extreme temperatures, and anti-corrosive properties. Much like motor oil for a car, optimal function relies on keeping the oil relatively cool and clean.

Pressure applied from one end of a hydraulic system transfers to another through this fluid due to its low compressibility characteristics. As the oil travels through the system, it lubricates the various parts, decreasing their wear and leading to higher longevity. Because hydraulic oil is used nearly every flight, there is an inherent risk of contamination, and, as such, maintenance crews will typically check oil levels and sample a small amount to ensure there is not enough contamination to possibly affect proper function.

Different components work on and with the oil in a hydraulic system. Valves are a crucial component in hydraulic systems as the entire system is dependent on the fluid traveling in a particular direction. One commonly used type of valve is the check valve which works by checking the pressure on the entrance end of the valve and comparing it to the exit. If the exit side contains an equal or higher pressure to the entrance, the valve will close and block oil from flowing backward.

Hoses are the “veins” of the hydraulic system as they are the vessel in which the fluid travels. Modern hydraulic hoses have three layers: an inner tube, reinforcement layer, and protective layer. The inner tube carries the fluid and must be compatible with it. Like the oil itself, inner tubes must be flexible and heat resistant. The reinforcement layer is usually made out of a durable braided material that must withstand transient high-pressure situations. Finally, the protective coating or sleeve protects the inner two by being tear-resistant.

Coolers, also known as heat exchangers, work to cool the fluid in a hydraulic system which gets very hot as part of routine operation. Hot oil could potentially damage components and increase wear which leads to more frequent and costly repairs. As hydraulic fluid passes through an exchanger, the cooler forces cold air to lower the fluid’s temperature. These systems typically do not require power and are cheap to maintain.

Lastly, accumulators are parts that allow for a proper amount of fluid to be let into the system in dynamic situations. Accumulators hold some hydraulic oil as well as a compressible gas like nitrogen which increases the potential energy in the system. When extra fluid is needed in the system, the amount that is stored in the accumulator can be released quickly. Accumulators also carry the benefit of softening the overall noise of the system.

ASAP Aerospace Hub is a leading distributor of hydraulic systems for aviation. We source our inventory of over 3 billion new and obsolete parts from top manufacturers worldwide. Our customers deserve the best quality parts and service, which is why we are proud to operate as an AS9120B, ISO 9001:2015, and FAA AC 00-56B certified and accredited enterprise. If you are in search of a quick and competitive quote, please fill out our instant-RFQ form from our website, and a dedicated account manager will reach out to you in 15 minutes or less.


December 15, 2022

Recent Twitter Posts

Why Choose Us?

Low Price Warrantied inventory at competitive prices

Find it fast Search the world's largest inventory of electronic components by manufacturer, category or part number

Quality guaranteed We sell only warrantied and traceable parts

Get it fast All inventory ready to ship from our sellers

Semiconductor's Certifications and Memberships

Thank You for Visiting Us today.

Remember Us When You’re Looking for Competitively Priced, High-Quality Aviation Parts.

Request for Quote

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.