Auto brake parts

Brake: key insights into component performance, mounting, diagnostics, and durability

A braking system comprises several components designed to ensure a controlled stop of a vehicle at a particular moment. It is also used to prevent the car from rolling when the driver needs to park it on a slope.

Brake system design

There are several types of brake systems. Nowadays, the most widespread layout is a hydraulic system with disc brakes. Its key elements are the following:

• Pedal – by depressing this, the driver operates the system.
• Brake booster – this multiplies by several times the force applied to the pedal to make the system work efficiently.
• Master brake cylinder – this creates the pressure required for the operation of many actuating mechanisms.
• Hoses and pipes – these ensure that the working fluid is supplied to the cylinders.
• Pistons – the fluid pressure forces these out of the cylinders, and they press the brake pads against the discs.
• Caliper – this is used as a housing for pistons and pads. In floating components, the calliper bracket presses one of the pads to the disc.
• Pads – these are elements of the friction pairs and have a friction surface. When the driver depresses the pedal, they are pressed against the brake disc. The friction force created between them stops the wheel rotation.
• Discs – this is the second element of the friction pair. It is mounted onto a wheel hub and rotates together with it.

In drum brakes, brake shoes together with the wheel brake cylinder are installed inside the drum. When the pedal is engaged, the brake fluid pressure pushes out the pistons of the wheel cylinder. They overcome the resistance created by return springs and press the brake shoes against the internal surface of the drum.

Parking brake systems are fitted with a cable instead of a hydraulic actuator.

Maintenance advice

1. Replace the fluid once every 2–3 years. It absorbs moisture through the pores in rubber hoses. With time, the concentration of water in the braking fluid rises and its boiling point reduces significantly. If the fluid boils, air locks appear in the system, which decreases its efficiency dramatically.
2. Replace the hoses every 5 years. The rubber and other polymers they are made of are subjected to wear and tear. Over time, they lose elasticity. As a result, the high pressure created in the system is neutralised by the excessive width of the hoses. The remaining pressure is insufficient to move the pads or shoes and press them against the disc or drum.
3. Measure the thickness of discs and pads regularly and replace them if needed. A worn-out disc may even crack. Due to wear and tear of the friction lining, it becomes impossible to achieve the required level of friction.
4. Lubricate calliper guide pins and replace the sealing elements every now and then. This way, you’ll prevent jamming of the assembly and uneven wear of the pads.
5. Use anti-squeal shims. They will help to avoid squeal and make braking more comfortable.

Symptoms of malfunction

When the brake fluid level warning light comes on, this usually means that some brake system components are leaking. In that case, you may notice yellow, amber, pink, grey, blue, or purple puddles under the vehicle after it’s been parked for a while, usually around the wheels. The car may pull to one side, which is often a sign of a jammed calliper. Similar symptoms appear when oil gets onto the pads, while increased pedal travel or low pedal resistance usually indicate that there’s air in the system.

Causes of malfunction

Most often, these problems appear when the driver neglects to replace brake system components on time. For example, a jammed calliper may cause uneven pad wear and deterioration of the brake disc. Old seals and hoses lose their elasticity and crack, causing the system to start leaking. Worn-out guide pin boots often lead to dirt and moisture getting on contacting parts, resulting in corrosion and jamming. Aggressive driving may lead to disc deformation.

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Useful information on functions, causes of malfunction, diagnosis and replacement intervals

• Rear and front brake pad replacement cost and intervals
• Difference between drum brakes and disc brakes: which are better?