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Train synthetic brake shoe. How does it work?
Jan 29, 2018

Before we start today, I'd like to introduce the brake shoe.

Brake pads on the railway language called brake shoe, brake shoe, is located in the wheel tread when to brake, through the role of the brake machine, will let the wheels before and after the two pieces of brake shoe wheel clamping, achieve the goal of parking.

Need to brake the train running process, and the contact friction wheel tread, will train the kinetic energy into heat energy into the atmosphere, to train to slow down or stop the operation of the components, direct is the brake shoe friction wheel to make the train parking brake parts.

A tile brake block made of cast iron or other material that holds the wheels of the wheel while braking and stops the wheels from turning by friction.

Brake shoe material can be divided into cast iron brake shoe and synthetic brake shoe.

Synthetic brake shoe.

Also known as non-metal sluice, it is made of asbestos and other fillers made of resin or rubber as a binder.

Synthetic brake shoe also should be reinforced with steel back.

If the brake shoe is pressed into a sheet for disc shape movement, it is called a brake.

Synthetic brake shoes were first used on London underground vehicles in 1907.

Since the 1950s, applications have become increasingly common.

Synthetic brake shoe weight light, wear-resistant, brake when basically no spark.

It with the coefficient of friction between the steel wheel, along with the change of speed increase and the change of the brake adhesive coefficient between wheel/rail, in order to better use of adhesion effect, improve the parking brake performance and shorten the braking distance.

The synthetic brake shoe has high friction coefficient and low friction coefficient.

High friction coefficient composition brake shoe friction coefficient is about twice that of cast iron brake shoe, can use the smaller the diameter of the cylinder and air cylinder, so as to reduce the weight of the foundation braking device, and can save the compressed air, more advantages.

Low friction coefficient synthetic brake shoe can directly replace cast iron brake shoe, suitable for the use of old car.

The disadvantage of the synthetic brake shoe is that the thermal conductivity is poor, the heat generated by friction increases the temperature of the wheel tread, and even causes the hot crack in the surface of the tread.

In recent years, in order to avoid pollution of the environment, the synthesis of asbestos, lead-free and other hazardous materials has been adopted more and more.

So how does it work?

The braking principle of train brake shoe: in the process of train braking, the braking device should transform the huge kinetic energy into the heat energy dissipating into the atmosphere.

However, the braking effect depends mainly on the dissipation capacity of the friction heat.

When using this braking mode, the friction area of the brake shoe is small, and most of the heat load is borne by the wheel.

The higher the train speed, the greater the thermal load of the wheel when braking.

If cast iron brake shoe, temperature can make brake shoe melting;

Even with more advanced composition brake shoe, the temperature will be up to 400 ~ 450 ℃.

When the temperature of the wheel tread increases to a certain degree, it will cause the tread wear, crack or peeling, affecting the service life and driving safety.

It can be seen that the traditional brake shoe brake can not adapt to the needs of high-speed trains.