MIDTERMS L3: Landing Gear

Aircraft Brakes

Are used to slow down or stop the aircraft

Main landing gear wheels

Aircraft Brakes are installed on the ____

Toe brakes (rudder pedals)

Aircraft brakes is operated by the pilot using ___

Mechanical/hydraulic linkages

____ allows the pilot to control the brakes (rudder pedals)

Heat energy

In aircraft brakes, it converts the kinetic energy of motion into ____ through the creation of friction.

▪Single Disc Brake

▪Floating Disc Brake

▪Fixed Disc Brake

▪Dual Disc Brake

▪Multiple Disc Brake

▪Segmented- Rotor Disc Brake

▪Carbon Brakes

Types and Construction of Brakes

Single Disc Brake

▪Commonly used in small or light aircraft

▪Uses one brake disc (rotor) attached or bolted to the wheel.

▪Disc rotates together with the wheel.

▪A fixed (non-rotating) caliper is mounted on the landing gear

Floating Disc Brake

• Brake disc is allowed to move slightly sideways (float)

• It has three cylinders bored through the housing, but on other brakes this number may vary.

• Helps ensure even contact between disc and brake pads

• Reduces uneven wear of brake linings

Fixed Disk Brake

• Brake disc is rigidly mounted (does not move)

• Linings are riveted to the pressure plate and backplate.

• Caliper slides using anchor bolts and bushings. This movement allows the brake to center itself on the disc

Dual Disc Brakes

▪ A single disc on each wheel does not supply sufficient braking friction

▪ Two discs are keyed to the wheel instead of one

▪ It is similar to a single-disc brake. It uses a center carrier to hold brake linings against each of the discs

Multiple Disc Brakes

• Used in large, heavy aircraft for strong braking

• Heavy duty brakes designed for use with power brake control valves or power boost master cylinders.

• Contains several discs stacked together (rotor and stator discs)

• Common in commercial and transport aircraft

Segmented-Rotor Disc Brakes

▪Used in high-performance or heavy aircraft systems.

▪Developed to dissipate large amounts of heat in high-performance and large aircraft

▪Designed for high-pressure hydraulic power brake systems

Rotors are slotted or built in sections with gaps

Carbon Disc Brakes

▪Made from carbon composite materials instead of steel.

▪Can withstand very high temperatures.

▪Approximately 40% lighter than conventional steel brakes

▪High cost is the main limitation, but expected to decrease with technology improvements

1. Independent system

2. Booster system

3. Power brake system

What are the 3 Brake Actuating Systems?

independent system

____ system

Not part of the aircraft main hydraulic system

Booster system

_____ system

uses the aircraft hydraulic system intermittently when needed

Power brake system

_____ system

only uses the aircraft main hydraulic system(s) as a source of pressure

Independent Master Cylinders

▪Commonly used in small, light aircraft and aircraft without a main hydraulic system

▪Completely independent and not connected to the aircraft’s main hydraulic system

▪Uses master cylinders to generate hydraulic pressure for braking

System operation is similar to an automobile brake system

Boosted Brakes

▪Used in medium and some larger aircraft

▪Designed to increase braking force beyond pilot’s foot pressure

▪Combines pilot input + hydraulic system assistance

A boosted master cylinder is mechanically connected to the pedal

During light braking

Boosted Brakes: System operates similar to a normal hydraulic system

During heavy braking

Boosted Brakes: Hydraulic boost activates additional pressure is supplied from the aircraft hydraulic system

Power Brakes

▪uses the aircraft’s main hydraulic system as the primary source of power to operate the brakes

▪It is designed for large and high-performance aircraft where very high braking force is required

It uses a control (metering) valve to regulate hydraulic pressure based on pilot input

Emergency brake system

• large aircraft are designed with multiple safety features and backup systems to ensure braking is always available

• System use more than one hydraulic source, independent brake assemblies, and emergency power sources to maintain braking capability even in case of failure

Parking Brakes

▪holds the aircraft in a stationary position when parked or during ground operations

▪lock the brakes in the applied position after they are engaged by the pilot

▪A combined mechanical and hydraulic system that maintains brake pressure without continuous pedal input

Brake Deboosters

▪Used in power brake systems to reduce hydraulic pressure before it reaches the brake assembly

▪Some brake assemblies are not designed to withstand full system hydraulic pressure

▪Prevents damage to brake components due to excessive pressure

Anti-Skid System

consist of multiple components working together automatically

▪is a safety feature used in aircraft with power brake systems to prevent the wheels from locking and skidding during braking

▪It automatically controls and adjusts brake pressure to maintain proper wheel rotation and ensure safe braking

▪Essential in large and high-performance aircraft, especially those with multiple-wheel landing gear assemblies

• Wheel Speed Sensor

• Control Unit

• Anti-Skid Control Valve

3 main types of components in Anti-Skid system

Wheel Speed Sensor

▪are transducers that convert mechanical wheel rotation into electrical signals

▪Installed on each wheel with a brake assembly

▪They may be alternating current (AC) or direct current (DC)

Control Unit

▪It can be regarded as the brain of the anti-skid system. 

▪It receives signals from each of the wheel sensors and makes decisions to prevent skidding

▪Automatically controls brake pressure adjustments without pilot intervention

Anti-Skid Control Valve

▪iAn electrically controlled hydraulic valve that uses a torque motor, flapper, and spool mechanism to regulate brake pressure based on signals from the control unit

▪They respond to signals from the anti-skid control unit

▪Responsible for regulating hydraulic pressure to each brake assembly.

▪Each brake assembly has its own individual control valve