Brake part descriptions
A - Z
ABS Control Module
The ABS Control Module manages the anti-lock braking system. It prevents wheel lockup during braking by controlling brake pressure to each wheel. A failing module can cause illuminated warning lights, loss of anti-lock braking ability, and unintended ABS activation.
ABS Differential Sensor
The ABS differential sensor transmits the speed of the differential ring gear to the ABS control module, which calculates vehicle speed. Symptoms of a failing sensor include illumination of the ABS warning light and improper ABS activation. Not all vehicles with ABS use this sensor; some employ individual wheel sensors instead.
ABS Pump
The ABS pump provides supplemental brake fluid pressure, in addition to the pressure created by the driver, to operate the ABS system effectively. A failing ABS pump may trigger the ABS warning light.
ABS Valve Assembly
The ABS valve assembly, controlled by the ABS module, modulates brake fluid pressure to each wheel’s brake mechanism. It prevents wheel lockup during braking, especially in slippery conditions, ensuring tires maintain grip for safe stops. A failing assembly can cause various issues, including illuminated warning lights and compromised braking performance.
ABS Wheel Speed Sensor
The ABS Wheel Speed Sensor monitors wheel rotation speed and sends signals to the ABS computer. Faulty sensors can trigger warning lights, disable ABS, and affect stability and traction control systems. Prompt replacement is recommended if issues are detected.
Anti-Lock Brake System
A safety feature that prevents wheels from locking up during braking. It uses wheel speed sensors to monitor each wheel and temporarily reduces hydraulic pressure when skidding is detected. This allows drivers to maintain steering control and helps prevent accidents by enabling them to steer around obstacles.
Brake Booster
The brake booster between the brake pedal and master cylinder. It multiplies the force applied to the brake pedal, enhancing braking power. There are three types: vacuum, hydro-boost, and electrohydraulic. A failing booster can cause hard pedals, increased stopping distances, and various system-specific issues.
Brake Caliper
Uses hydraulic pressure to squeeze brake pads against the brake disc, creating friction to slow or stop the wheel. A malfunctioning calliper can cause various issues, including reduced braking power, pulling to one side, and unusual noises.
Brake Drums
Brake drums are circular metal components that house brake shoes in a vehicle’s braking system. They create friction to stop the vehicle when brake shoes press against them. Signs of bad brake drums include noise, low or spongy brake pedal, pedal pulsation, and parking brake issues.
Brake Flexible Hose
Brake flexible hoses connect rigid metal brake lines to calipers and wheel cylinders, allowing free wheel and suspension movement. Signs of failure include slowly sinking pedals, visible cracks, uneven braking, and brake drag. When replacing due to blockage or cracking, inspect or replace all hoses and flush the hydraulic system.
Brake Fluid
Brake fluid is a specially formulated, glycol-ether-based fluid that transmits pressure from the master cylinder to the calipers and wheel cylinders when the brake pedal is pressed. It maintains constant viscosity, low compressibility, high boiling point, and corrosion resistance. Brake fluid lubricates moving parts and protects against corrosion in the braking system.
Brake Master Cylinder
The brake master cylinder pressurises brake fluid when the brake pedal is pressed, transmitting force to the wheel brakes. Signs of failure include a sinking brake pedal, dragging brakes, fluid leaks, and illuminated brake warning lights.
Brake Pad Wear Sensors (Electrical)
Brake Pad Wear Sensors (Electrical) are components attached to or integrated into brake pads. They trigger a warning on the instrument cluster when brake pads wear down to the point of needing replacement. Ignoring this warning may damage rotors or calipers. These sensors should be replaced along with brake pads.
Brake Pad Wear Sensors (Mechanical)
Brake Pad Wear Sensors (Mechanical) are small metal tabs on brake pad backing plates designed to create a squealing or scraping noise when pads wear down, signaling the need for replacement. They contact the rotor surface when pads are critically worn, alerting drivers to service their brakes.
Brake Pads
Brake pads are positioned on either side of each brake rotor and squeeze the rotor when brakes are applied, bringing the vehicle to a stop. Brake pads come in three main types: organic, metallic, and ceramic, each with distinct characteristics.
Brake Rotor
Brake rotors, also known as brake discs, provide a friction surface for brake pads to grip, enabling the vehicle to stop. Rotors can be solid or vented and are typically found at each wheel in modern cars
Brake Shoes
Brake shoes are curved metal components with friction lining, typically found on rear wheels or in parking brake systems. They press against brake drums to create friction and stop the vehicle. Signs of wear include noise, low or grabby brake pedal, reduced stopping power, and parking brake issues.
Hub Assembly
A hub assembly is a component of a vehicle’s wheel system, combining the wheel hub, bearings, and ABS sensor into a single unit. It connects the wheel to the suspension and allows for smooth rotation while supporting the vehicle’s weight.
Parking Brake Shoes
Parking brake shoes are small brake components located inside the drum portion of rear disc brake rotors. They are actuated by cables when the parking brake is applied, pressing against the inner drum surface to hold the vehicle in place.
Wheel Cylinder
The wheel cylinder is typically found on rear wheels of modern vehicles. It converts hydraulic pressure from the brake pedal into mechanical force, pushing brake shoes against the brake drums to slow or stop the car.