How the Aircraft Braking System Works?

Early aircraft utilized a single braking system with no backup or failsafe. The system was simplistic in design and eventually deemed unsafe, causing the regulating authorities to incorporate robust overhauls. Airlines had to address the issue of potential loss of the primary hydraulic pump, which led to the implementation of electrically driven pumps that provided an alternate supply of hydraulic pressure. However, these solutions didn’t address the loss of fluid issue. Some manufacturers began incorporating a compressed air system for emergency braking, yet, there was only a limited amount of air the tanks could hold. This led to the concept of multiple, independent hydraulic systems backed up by accumulators. This system proved to be effective as it allows for several layers of failure without losing total control of the braking system; a concept that is still used today.

For something that has such an important job, the braking system on light aircraft is simple. These planes use a single-disc system that is operated by a toe brake mechanism. When you activate the brake, a master cylinder pushes hydraulic fluid through hoses to the brake unit housing that is attached to the landing gear strut. A piston within the housing is triggered by the pressure, which then pushes against a brake disc, causing the plane to slow.

Floating disc brakes are another type of braking system you can find on aircraft. In this design the caliper hugs the brake disc. It can have 3-6 cylinders that run through the housing depending on the application. Each cylinder has an actuating piston that consists of an automatic adjusting pin, a return spring, brake linings, and the piston itself. When the brakes are applied the pistons move from the cylinders toward the disc, enabling the brake linings to contact the disc and apply friction evenly on both sides. This slows the rotating motion of the wheel, ultimately causing the plane to slow down.

Another common type of aircraft brake is the fixed-disc brake. The disc is bolted to the wheel and allows the brake caliper/linings to float laterally when pressure is applied. This design allows the caliper to adjust position in relation to the disc. When the system is activated, the caliper and linings center on the disc via a sliding action of the anchor bolts. Equal pressure is applied to both sides of the disc, slowing its rotation.

Other methods of braking exist outside of the actual brake component. Reverse thrust is used in conjunction with these systems to ensure proper stoppage. This consists of reversing the engine flow to counteract the natural forward direction of an aircraft in motion. Parachutes are used in military aircraft to assist in stopping due to their natural high-speed capabilities. On aircraft carriers, catapults are used.

1. gary anderson
2. Posted on May 16, 2019
3. aerospace

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