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The types of brakes

The types of brakes

In modern vehicles two main types of brakes are used: drum and disc brakes. The reliability of the braking system directly depends on the safety of the driver on the road while driving.

Drum brakes are a kind of braking system that works by means of a special rotating element of a cylindrical shape and pads. When the brake pedal is depressed, the pads inside the drum are pressed against it, slowing down the cylinder’s rotation speed. This leads to braking of the vehicle.

Unlike the drum brake, the disc brake system uses a thin disc that can be attached to both the front and rear wheels of the car. There are also pads that compress the disk and lead to braking.

History of the origin of drum and disc brakes

Some types of elementary brake systems were invented even before the invention of the car. They were used to equip horse-drawn carriages. In 1768, the first prototype of a car was created – a steam engine that could transport people. A simple shoe brake was used here. However, after the creation in 1885 of the first cars and motorcycles that had a design similar to modern, the braking systems began to rapidly improve.

When cars started to reach speeds up to 100 kilometers per hour. It’s time to think about the stability of the brakes. And the famous English engineer Frederick William Lanchester created the first disc brakes in 1902. However, such a system had a significant drawback: the pads were made of copper, which, when rubbed against the disk, produced a terrible squeak. In this regard, the first disc brakes were not very popular.

In the same year, in 1902, but somewhat later, the French inventor, as well as the founder of the Renault car company, Louis Renault, invented his own brake system – a drum brake. Despite some changes in the design of this brake, it is the system invented by Louis Renault that today is called “drum”. Unlike the disk brake system, the drum drum was in great demand until the 50s of the 20th century.

However, a few years after the invention of 1918 hydraulic drive for brakes Malcolm Lowhead, the situation has changed significantly. The hydraulic system made it possible to reveal the potential of disc brake systems. All this happened gradually, but a real “boom” happened in the 50 years of the twentieth century, after the disc brake systems were installed on luxury cars “Jaguar”. Over time, the design of the drum brakes has not undergone any changes, but the disk, on the contrary, has been constantly improved. Despite the fact that more than 100 years have passed since the invention of these braking systems, they are still in demand among drivers and automakers. At the moment, these types of braking systems have different degrees of reliability and efficiency.

Basic principles of the disc and drum brakes

To understand how to use a drum or disk brake system, you need to understand in detail the principle of their action.
Drum brake systems provide a stop for the vehicle as follows:

  • When pressing the pedal to stop the car, there is pressure in the hydraulic drive with the operating oil.
  • The oil provides pressure on the rotating cylindrical element.
  • The drum is equipped with valves that act on the pads, overcoming the resistance of special springs.
  • The shoes are in tight contact with the cylinder moving around its axis, reducing the speed of its rotation.
  • There is friction between the brake shoe and the rotating element, which contributes to the braking of the vehicle
  • At the moment the brake pedal is released, all the parts of the mechanism return to their original position.

The principle of the disc brake system is different from the drum:

  • When the driver presses on the brake pedal, the brake master cylinder initiates pressure in the brake pipes.
  • Thanks to pressure, special pads begin to tightly contact the rotating disc.
  • Due to the frictional force that arises between the disc and the pads, the vehicle brakes.
  • When the driver lowers the “brake”, thanks to the elasticity of the brake system parts, the mechanism returns to its original position.

Another important detail: thanks to the shape, a parallel contact patch is created between the discs and pads, which increases the frictional force and contributes to more effective braking. Due to the cylindrical shape of the drum brake system, a semi-circular contact patch is created, which reduces the braking efficiency of the vehicle.

Pros and cons of the drum and disc brakes

Like any other system, drum and disc brakes have their advantages and disadvantages. Depending on these criteria, different types of brakes are installed on different types of vehicles.

The advantages of drum brakes are as follows:

  • Producing them is much easier and cheaper, unlike disk brake systems.
  • The system is not contaminated. The working space of the cylinder is closed and protected, which prevents the ingress of dirt inside.
  • Durability. Since the frictional force between the pads and the drum is much smaller and the working surface is larger, this reduces the wear of the drum brake system.
  • Simple and convenient design.
  • Braking the car with a handbrake is much easier and easier.
  • At operation the mechanism allocates much less thermal energy, than disk brake system. Drivers can save a lot on the working fluid.

Also it is possible to allocate such lacks of a drum brake:

  • Due to loose friction and a small working area, the contact between the pads and the ram is considerably less than in the case of a disc braking system. This can lead to unstable braking and worsens the grip of the vehicle with the road surface.
    The pads press on the drum from the outside. This can lead to the fact that under pressure the working cylinder can simply burst.
  • Drum brake systems overheat. Unlike a flat disc, the drum has a more voluminous shape. This prevents the ingress of a hollow part of the air to cool the structure. If the car stopped in an emergency situation, the temperature inside the cylinder could reach 500-600 degrees Celsius.
  • If the ambient temperature is too low or too high, sticking of the pads in the drum may occur. This can happen if you put the vehicle on a handbrake.
  • Great weight and size of the design.

It is believed that disc brakes are more efficient and reliable, but they also have their pros and cons, compared with drum brakes.

The advantages of disc brakes are as follows:

  • Due to the flat shape of the disc, this kind of brake system is less overheated.
  • Compactness.
  • Immunity to temperature conditions of the environment.
  • Great efficiency due to high frictional force and a smaller working surface.
  • To replace the disc brakes on the front wheels is much easier than the drum brakes.
  • Detect defects and problem areas in disk brakes is much easier.

There are also significant disadvantages of disc brake systems, among them:

  • Short-lived compared to drum braking systems. Due to the large frictional force between the shoe and the disc, the mechanism wears out more quickly. For example, the drum brake system has a resource of more than 100 thousand kilometers, and the disk brake system – no more than 40 thousand kilometers.
  • Disc brake systems are highly contaminated.
  • Braking a vehicle with a handbrake is much more difficult, compared to a drum mechanism.
  • The replacement of the disc system on the rear wheels is more difficult.
  • High cost compared with drum brakes.
  • If the car is idle for a long time, it can lead to rusting of the disc. In this case the replacement must be made.

What kind of brakes is more popular among drivers and automakers

Despite the fact that the disc brakes were invented earlier than the drum brakes, they are more reliable, therefore, the demand for them is higher. But the old budget models of cars still have drum brakes.

Some domestic and foreign car manufacturers equip the rear wheels of SUVs with drum brakes. This is due to the longevity of this type of brake. In addition, it is advisable to put the drum brake system on the rear wheels of the car. The thing is that the rear wheels are more prone to contamination, because all the dirt from the front wheels flies back. A drum brake system is perfectly protected against moisture and dirt due to the volume form of the cylinder.

Despite the fact that drum brake systems are still used in the production of vehicles, they become irrelevant, because they can not cope with the speeds of modern cars and produce efficient and reliable braking. As among drivers and automakers, disc brake systems are used much more often.


Date: 18.11.18     Views: 127