Mechanical Engineering - Automobile Engineering - Discussion

When we applied brake, brake fluid helps to transmit brake power to the brake shoe. Due to frequent use of brake, temperature of the fluid present in it raises. When fluid temperature get raised above boiling point, it converted into vapor. Vapor is more compressible as compare to fluid resulting in auto locking of brake which may cause accident.

Is this vapour changes to the liquid state when is cooled so that the brake gets restored to the normal state?

Due to their hygroscopic nature, they absorb moisture from atmosphere resulting in a decrease in boiling temperature and hence changing the fluid in vapour state. As vapour is highly compressible the brake stops working.

These problems are taking place in the hilly area the car does not drive smoothly more time brakes can be held down.

While fluid goes to boil at a high temperature, it will formed into vapour. The density difference between the fluids causes to vapour locking in braking system.

The Hygroscopic nature of the glycol which is often used in now days modern vehicles can easily absorb water from any available surrounding.

This water so absorbed boils at 100'c (even far away from the fluids temperature). Vapour formed is compressible at high pressure hence making the brake to loss it's effect.

During the life of a vehicle or even a drum of brake fluid sitting on the floor of a workshop things happen to Glycol fluids because they are what we call "Hygroscopic". They absorb water even through the walls of the (would you believe) slightly previous rubber brake hoses and open top on cans or vehicle master cylinders.

This water vapour drawn into the fluid will of course boil at somewhere around 100 degrees (or a little more under Pressure) so any water content in a brake fluid is bad news. It also causes system internal parts to corrode.

This is a term used when the brake fluid in a vehicle brake system is overheat and loses efficiency.

First we will explain what brake fluids usually consist of there are three main types of brake fluids, Mineral brake fluids, Glycol brake fluids and silicone brake fluids. The GLYCOL brake fluid is most common and used in 99.5% of modern vehicle brake systems.

There can be up to 2 pints of brake fluid used in a vehicle brake system and this is piped around the vehicle using copper or rubber hoses to feed the fluid from the operator to the brake system.

Operating the brake forces the fluid into the master cylinder and then brake calipers or wheel cylinders to actuate the brake.

Basically Brake Fluid are of mainly three types:

1) Mineral.
2) Glycol.
3) Silicone.

Mainly in all of the automobile Glycol is used as Brake Fluid.

Glycol is Hygroscopic in nature, So it absorb Water from the environment during its life from the Master Cylinder, Rubber Hose etc.

Due to Severe Braking or Continuous Braking the temp of the Fluid Rises and Water will convert into Vapour at 100'C.

Being Compressible in nature it lead to loss in Braking Effect or termed as Vapour lock in Brake System.

If there is a problem of vapor lock in break system.

Can any one tell me how to over come this problem.