Everything You Need To Know About Hydraulic Disc Brakes

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There are mainly two types of Disc brakes used nowadays: mechanical disc brakes, which operates with cables and hydraulic disc brakes, which operates with hydraulic fluid in a fully sealed line.

In this article, we will discuss Hydraulic Disc brakes which are commonly used.

disc brakes

What Is A Hydraulic Disc Brake?

Hydraulic disc brakes are a type of disc brake in which hydraulic fluid is used instead of wires in a fully sealed line.

Construction Of Hydraulic Disc Brakes

The most common arrangement of hydraulic disc brakes for rider vehicles, motorcycles, scooters, and mopeds, consists of the following:

  • Foot pedal or lever
  • A pushrod (also known as associate degree activating rod)
  • A brake cylinder assembly containing a piston assembly (made from either one or 2 pistons, a come spring, a series of gaskets/ O-rings and a fluid reservoir)
  • Reinforced hydraulic lines
  • Brake calliper assembly sometimes consisting of 1 or 2 hollow metal or chrome-plated steel pistons (called calliper pistons), a group of thermally conductive restraint associate degreed a rotor (also known as a brake disc) or drum hooked up to the shaft.

The system is typically full of a glycol-ether primarily based brake fluid (other fluids may additionally be used).

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At just once, rider vehicles ordinarily utilized drum brakes on all four wheels. But disc brakes have shown higher chilling and larger resistance to ‘fading’ and area unit thus usually safer than drum brakes.

Working Principle Of Hydraulic Disc Brakes

In a hydraulic disc braking system, when the foot pedal is flattened, a pushrod puts forth the force on the piston(s) within the brake cylinder, causing fluid from the brake fluid reservoir to flow into the pressure chamber through a compensating port. This ends up in a rise within the pressure of the complete mechanism, forcing fluid through the hydraulic lines toward one or a lot of callipers wherever it acts upon one or a lot of calliper pistons sealed by one or a lot of seated O-rings (which forestall outpouring of the fluid).

The brake calliper pistons then apply force to the restraint, pushing them against the spinning rotor, and therefore the friction between the pads and therefore the rotor causes a braking torsion to be generated, retardation the vehicle. The heat generated by this friction is either dissipated through vents and channels inside the rotor or is conducted through the pads, that unit of measurement factory-made from specialised heat-tolerant materials like kevlar or forge glass.

working of hydraulic disc
                  Source: wikimedia.org

Following the unharness of the brake pedal/lever, it allows the spring(s) within the brake cylinder assembly to take the master piston(s) back to position. This action reduces the hydraulic pressure on the calliper, then applies suction to the brake piston at the calliper assembly, moving it back to its spot and allowing the obstacle to unhitch the rotor.

The hydraulic braking system is intended as a closed system: unless there’s a leak within the system, none of the brake fluid enters or leaves it, nor will the fluid get consumed through use. Outpouring could happen, however, from cracks within the O-rings or a puncture within the brake line. Cracks will kind if 2 forms of brake fluid area unit mixed or if the brake fluid becomes contaminated with water, alcohol, antifreeze, or any range of alternative liquids

Advantages Of Hydraulic Disc Brakes

Below we have listed some of the advantages of Hydraulic Disc Brakes.

  • No adjustment needed. So, no maintenance.
  • Better stopping performance
  • Fade-free braking altogether conditions. So, no attenuation of brakes.
  • Can check wear while not activity the unit
  • Easy to replacement of pads compared to Drum brakes.
  • More stopping
  • Reach adjustment.

Disadvantages Of Hydraulic Disc Brakes

Below we have listed some of the disadvantages of Hydraulic Disc Brakes.

  • High braking force required compared to hydraulic brake
  • A low lifetime of restraint compared to brake shoes
  • Need separate hand-brake mechanism once fitted to rear wheels.


So we have discussed the construction, working principle, advantages and disadvantages of hydraulic disc brakes.

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