Hydraulic Brake system

BRAKE SYSTEM :-

a brake consisting of a combination of interacting parts that work to slow a motor vehicle as shown in brake system diagram

Types of Brakes :-

Brakes are one of the most important safety features on your vehicle.  There are different types of brakes, both between vehicles and within a vehicle.  The brakes used to stop a vehicle while driving are known as the service brakes, which are either a disc and drum brake.  Vehicles also come equipped with other braking systems, including anti-lock and emergency brakes.

The most common types of brakes found in automobiles today are typically described as hydraulic, frictional, pumping, electromagnetic, and servo. Of course, there are several additional components that are involved with make braking smooth and more effective depending on road conditions and different circumstances.

Some common types of braking systems include:-

1- Disc brake

The primary components of disc brakes are: the rotor, caliper and brake pads. 

The disc brake system converts the hydraulic pressure generated at the master cylinder into a frictional clamping force against the rotating discs. 

Disc brake rotors :-The brake disc rotates with the road wheel. It provides a smooth surface against which to force the brake pads, to slow or stop the vehicle.

 Disc brake calipers :-  Disc brake calipers provide a housing for the hydraulic piston or pistons that force the brake pads into contact with the disc.

Disc brake pads :- A disc brake pad has a rigid, molded, friction material bonded to a steel backing plate for support during brake application. It transforms the hydraulic force of the caliper into a frictional force against the disc.

 Brake pads and linings are made from materials which have a high coefficient of friction. The choice of material depends on the braking application, but it needs to be able to absorb and disperse large amounts of heat without braking performance being adversely affected.

How disc brake works !!

As it shown in a schematic

In a hydraulic brake system, when the brake pedal is pressed, a push rod exerts force on the piston(s) in the master cylinder, causing fluid from the brake fluid reservoir to flow into a pressure chamber through a compensating port. This results in an increase in the pressure of the entire hydraulic system, forcing fluid through the hydraulic lines toward one or more calipers where it acts upon one or two caliper pistons sealed by one or more seated O-rings (which prevent leakage of the fluid).

The brake caliper pistons then apply force to the brake pads, pushing them against the spinning rotor, and the friction between the pads and the rotor causes a braking torque to be generated, slowing the vehicle. Heat generated by this friction is either dissipated through vents and channels in the rotor or is conducted through the pads, which are made of specialized heat-tolerant materials such as kevlar orsintered glass.

Subsequent release of the brake pedal/lever allows the spring(s) in the master cylinder assembly to return the master piston(s) back into position. This action first relieves the hydraulic pressure on the caliper, then applies suction to the brake piston in the caliper assembly, moving it back into its housing and allowing the brake pads to release the rotor.

The hydraulic braking system is designed as a closed system: unless there is a leak in the system, none of the brake fluid enters or leaves it, nor does the fluid get consumed through use.

What  are  the  advantages  and  disadvantages  of  disc  brake ??

Drum Brakes:-

                                          The primary components of the drum brake system are: the backing plate, the brake drum & brake shoe assembly, the wheel cylinder, retaining clips & springs and automatic brake self-adjuster.

Backing plate:- The backing plate is bolted to the axle housing or suspension member. It provides a mounting for the wheel cylinders and brake shoes to act against the rotating drum.

Brake linings & shoes :- The brake lining is a specialized friction material, riveted or bonded to a steel shoe. The shoe transfers the wheel cylinder movement and forces the lining against the rotating drum

Wheel cylinders:- The wheel cylinder and piston react to hydraulic pressure from the master cylinder, and the outward movement of the piston forces the shoe and lining against the drum.

How drum brake works !!

The drum brake system operates by forcing the friction-lined brake shoes against the inner surfaces of the 

rotating drums. The shoes are designed to operate with a self-energizing action.

Similar to the disc brake, the drum brake is comprised of a twin brake shoes along with a piston. But unlike, the drum brake also has anadjuster component, an emergency brake system and numerous springs. On striking the brake pedal, the piston thrusts the brake shoes towards the drum. Now the question is that what is the use of all those springs? The additional braking power exerted by the lodging movement makes the drum brakes to choose a smaller piston than disc brakes. But, because of the blocking movement, the twin shoe is pulled away from the drum on releasing the brakes. Some springs are used for this purpose other springs are helpful in holding the twin brake shoe in position. Drum brakes have been replaced by Disc brakes to a huge extent.

What  are  the  advantages  and  disadvantages  of  drum  brake ??

 list  of advantages of drum brakes:

• less expensive to produce

• slightly lower frequency of maintenance due to better corrosion resistance compared to disks.

• built-in self energizing effect requires less input force (such as hydraulic pressure).

• wheel cylinders are somewhat simpler to recondition compared to calipers.

minor weight savings, primarily from much smaller and lighter hydraulic cylinders vs. calipers

 list  of advantages of drum brakes

1. When the drums are heated by hard braking, the diameter of the drum increases slightly due to thermal expansion, so the shoes must move farther and the driver must press the brake pedal farther.
2. The properties of the friction material can change if heated, resulting in less friction. This can be a much larger problem with drum brakes than disc brakes, since the shoes are inside the drum and not exposed to cooling ambient air. The loss of friction is usually only temporary and the material regains its efficiency when cooled,but if the surface overheats to the point where it becomes glazed the reduction in braking efficiency is more permanent. Surface glazing can be worn away with further use of the brakes, but that takes time.

      3.   Excessive brake drum heating can cause the brake fluid to vaporize, which reduces                               the hydraulic pressure applied to the brake shoes. Therefore, the brakes provide less                             deceleration for a given amount of pressure on the pedal. The effect is worsened by poor                       maintenance. Brake fluid that is old and has absorbed moisture has a lower boiling point, so                   brake fade occurs sooner.