Hydraulic and Pneumatic Power Systems

In the early days of aviation, many flight surfaces and aircraft controls were handled through mechanical linkages and power. While this served well for smaller and simpler models, the rapid rise of larger aircraft with more complex systems required a more powerful method to ease control for the pilot. With the introduction of hydraulic and pneumatic power systems, pilots can rely on pressurized fluids such as oils and gases in order to achieve the force necessary for actuation. While both systems are fairly similar in their overall operations, each holds its unique capabilities and advantages that make them desirable for certain applications. In this blog, we will provide an overview of hydraulic and pneumatic power systems, allowing you to find the best fit for your needs.

With an aircraft hydraulic system, enclosed fluids are used to transfer pressure for the actuation of mechanical components and flight control surfaces. As liquids are incompressible, a high amount of force can efficiently be harnessed for controlling larger and heavier surfaces. As such, hydraulic fluid may be used to operate wheel brakes, landing gear, flaps, cargo doors, and much more. While almost all modern aircraft employ hydraulics for various controls, the amount of implementation often depends on the size and complexity of the particular model.

While hydraulic systems may vary, all rely on hydraulic fluid and some common components that assist in power generation and transfer. As the medium of energy transfer, hydraulic fluids serve as one of the most important aspects of the system. While many liquids may have the incompressible characteristics that would serve hydraulics well, the fluids chosen for aircraft always must have optimal viscosity, high flash points, adequate thermal capacity, and lubricant properties. With the use of hydraulic pumps, pressure can be built up within the system through the use of pistons, motors, cylinders, and more. As the hydraulic system is concerned with the use of fluids, plumbing components such as reservoirs, filters, valves, and accumulators all serve important uses to direct fluids and maintain their quality and pressure.

With the aircraft pneumatic system, pressurized gases are used for power transfer instead of fluids. As such, different components are utilized to properly pressurize and transport energy through gases. Nevertheless, pneumatic systems may also be used to operate brakes, doors, pumps, and various emergency devices. As compared to liquids, the gases of pneumatic systems are highly compressible, and thus confined spaces are used to create and harness energy.

To achieve the pressure necessary to transfer and route gases, a number of standard components are required. With air compressors, pressure can be added to gases for recharging the system whenever a surface or component is actuated through pneumatic force. Depending on the need of the aircraft, a number of air compressors with varying stages of compression may be used. To ensure that pressure does not build up to an unsafe level, the system utilizes relief valves which permit the escape of gases when pressure values reach unsafe levels. With the use of valves, restrictors, and other similar components, the route of gases can be controlled to ensure pressure always reaches its destination efficiently.

While the two systems are fairly comparable to one another, they do each have their advantages and disadvantages that set them apart. When procuring components, pneumatic systems tend to be lower in cost and are much more flexible in their use. They are also quite safe, and their actuation is rapid. Despite this, hydraulic systems can provide a much higher amount of force due to the incompressibility of liquids. Furthermore, the hydraulic system can carry out power transmission while lubricating and cooling components as well. Despite this, such systems can often run higher in cost and require more regular maintenance.

Whether you are in need of hydraulic or pneumatic system components, Aviation Purchasing Platform has you covered with our unrivaled inventory of over 2 billion parts. As a premier purchasing platform for all aviation needs, we can help you source heat exchangers, accumulator components, hydraulic pumps, and much more at competitive pricing. Begin the purchasing process today by submitting an Instant RFQ form and receive a personalized quote in just 15 minutes or less.


March 20, 2023

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