Repair of brake caliper. With your own hands or at a service station?
What a car's braking system is made up of
The brake system (BS) is put on any vehicle in order to ensure full control over its steering as well as the safety of road users.
This system has the following branches:
- main (working) – is designed to slow down the car to a value of 5.8 m/s2 and above, when it is travelling at a speed of up to 80 km/h and applied pedal force of up to 50 kg;
- Auxiliary (emergency) – is activated in case of malfunction of the main vehicle;
- Parking – serves to fix the vehicle in place for a long time.
Let's look at the main components of the braking system installed in a passenger car.
Brake master cylinder (MBC)
The structure serves as the centrepiece of the main TC. Its task – converting the force applied to the brake pedal into the pressure generated in the brake fluid, which then flows evenly through the working circuits.
Brake master cylinder
The brake cylinder is the central unit of the main TC.
The GTC is placed on top of the cover of the vacuum booster. And above the cylinder itself there is a 2-section tank with some volume of brake fluid necessary for partial compensation of its losses at evaporation or leakage from the vehicle.
Transparent walls with control marks are provided to adjust the level of brake fluid in the reservoir, as well as a special sensor that sends a signal of severe fluid loss by lighting up an indicator on the dashboard in the passenger compartment.
Vacuum brake booster
The vacuum booster is a complete unit with the brake master cylinder described above. Its components are: housing, diaphragm, tracking valve, pusher, GTZ piston rod and return spring.
The purpose of this mechanism – to assist the driver in braking moments.
In unforeseen situations in the process of car travelling, for more confident resetting of speed, emergency braking system is connected to the booster.
Brake system drive
This unit is used to control the braking mechanisms. There are 5 different designs: mechanical, hydraulic, electric, pneumatic and combined.
Brake discs and pads
Brake disc has two components: a centre section and a rotor.
The central part of the disc is made of cast iron, aluminium or other metals. It can be either an independent part or mated to the rotor.
The rotor is most often cast iron, as this alloy is slow to wear. The rotor is the ring-shaped surface that the brake pads interact with during braking.
The rotor is attached to the centre of the disc and the latter – to the hub of the car wheel.
To increase the cooling of the disc during operation, it is made with cavities for air circulation and ventilation.
Brake pad (simply, «shoe») – the main working component of the TC. The material from which it is moulded, – metal alloy with various impurities (ceramics, organic dust, etc.). The durability and cost of this part depends on which formula is used in its manufacture.
A pair of pads are placed on each wheel, which create braking acceleration by pressing against the caliper with spring elements. Both pads are fitted with special friction linings and are also fitted with a wear sensor.
A pair of pads is fitted to each wheel, which create brake acceleration by springing against the caliper.
This mechanism is of two types: floating and fixed (with one-sided and two-sided pistons).
Brake caliper
When the driver of the vehicle depresses the brake pedal, a special piston in the GTC starts pumping brake fluid, which flows through pipes and hoses to the brake caliper.
The caliper piston is pressurised to move forward. On one side of the piston the first movable brake pad is mounted and presses against one side of the disc, on the other side – the second, with a fixed mount. As a result, the brake disc on both sides is compressed by the pads, and due to their friction, the rotation of the disc on the wheel (and there are four in total) is slowed down and the car stops.
As you can see, there are many parts of a car's braking system that need to be inspected, diagnosed and replaced systematically.
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