What Is a Brake Caliper?
Brake calipers are one of the components of a disc brake, and their main function is to control the movement of the brake pads.
The brake caliper is an important component that holds the disc wheel, which rotates with the wheel, between the brake pads and generates frictional heat to stop the wheel from moving.
Uses of Brake Calipers
Disc brakes are used on the wheels of all kinds of vehicles, including automobiles, motorcycles, aircraft, agricultural machinery, construction equipment, and railroads, and all wheels that use disc brakes have brake calipers.
In recent years, disc brakes have also been used in commercial vehicles, where drum brakes are the norm.
Principle of Brake Calipers
By depressing the brake pedal in the driver’s seat of a car or pulling the brake lever of a motorcycle, hydraulic pressure is applied to oil called brake fluid.
The force of this hydraulic pressure is used to apply pressure to the pistons in the brake calipers, which in turn actuate the brake pads in the brake calipers. The brake pads press against the disc rotor, which rotates with the wheel, creating friction.
The heat generated by the friction causes the rotational energy (kinetic energy) of the wheel to be released in the form of heat energy, which reduces the rotational energy of the wheel and stops the wheel from moving.
Types of Brake Calipers
There are three types of brake calipers as follows:
- Floating type
- Opposed type
- Sliding caliper type
Each of these types has different features, advantages and disadvantages, and the brake caliper to be adopted depends on what is important to you.
Specifically, the floating type is installed on light cars and compact cars, the opposed type on sports cars, luxury cars, and commercial vehicles, and the sliding caliper type on passenger cars and trucks.
1. Floating Type
Also called the floating type or one-push type. The piston is pressed against the disc rotor from one side rather than both sides, making it the simplest structure among brake calipers. It has the advantage of being lightweight, inexpensive, and easy to install because it has only one piston and cylinder and few components.
On the other hand, the noise generated during braking (rattle sound) and low rigidity are disadvantages. Because of these characteristics, this type is mainly used in inexpensive vehicles, such as light cars and compact cars.
2. Opposed Type
Also called fixed-side or opposed-piston type.
It has a structure in which pistons are pressed against the disc rotor from both sides, and its merits are its high braking performance and rigidity. There are also types with two or more pistons.
On the other hand, the disadvantage of this type is that it is heavier and more expensive than other types because it has more pistons than other types. Because of their ability to provide stable control and braking performance, they are used in commercial vehicles, luxury cars, and sports cars that require greater braking force.
3. Sliding Caliper Type
Based on the floating type, the number of pistons is increased to two.
The two pistons are back-to-back, and when one piston is pushed out, the other piston is pulled in. This type of brake caliper has two pistons and one cylinder. It can be said that this type of brake caliper compensates for the weak point of low rigidity while retaining the advantages of the floating type, such as low cost and lightweight.
The greatest advantage of this type is that it has fewer disadvantages than the floating and opposed types.
Other Information on Brake Calipers
1. Life Expectancy and Replacement Period of Brake Calipers
Brake calipers are expected to last approximately 100,000 km. Brake pads, one of the components of brake calipers, have a shorter life than brake calipers because they are in direct contact with the disc rotor. Therefore, it is important to have brake pads inspected.
Therefore, it is recommended that brake calipers be inspected at the same time as brake pads. Also, if you notice any brake problems, such as poor braking performance or unusual noises, it is necessary to inspect and replace the brake calipers as soon as possible.
2. Sticking Brake Calipers
One of the most common problems with brake calipers is sticking. Sticking refers to a malfunction in which rust or dirt adheres to the pistons inside the Brake Calipers, causing the pistons to move sluggishly or become stuck, and the brake pads are unable to return from the position where they are pressed against the disc rotors.
This means that the brakes remain active while driving, leading to brake damage, which is dangerous. In particular, if sticking occurs on only one wheel, the brakes will be applied on only one side of the car, making it impossible to control the car and leading to a major accident.
Since brake calipers can be replaced relatively inexpensively, it is important to inspect and replace them regularly before they become sticking or otherwise malfunctioning.
3. How to Inspect and Maintain Brake Calipers
Brake calipers can be inspected and maintained by yourself, but the cost of having a mechanic perform the maintenance is approximately 150 USD. The following points should be checked during maintenance:
- Presence of rust
- Deterioration of piston seals and oil seals
- Filling of brake fluid