Master Cylinder Types: Working Process

This article discusses about master cylinder types, places where it is used and its working mechanism. The braking force applied by the driver is very less as compared to the actual force needed to stop the vehicle.

A master cylinder amplifies this braking force and is used to convert a mechanical force into hydraulic force. The hydraulic force is then again used for performing mechanical activities such as lifting weights or braking a car.

What is a master cylinder?

A master cylinder is a device used to convert a mechanical force to hydraulic force. This cylinder then controls the slave cylinders attached to the other end of the braking system.

A master cylinder is usually used in automotive industry mainly used to apply hydraulic pressure. These cylinders are commonly used in braking systems in automobiles. It is a very important machine component.

master cylinder types
Image: Master cylinder

Image credits: Ildar Sagdejev (Specious), 2008-04-21 1990 Geo Storm GSi master cylinderCC BY-SA 4.0

Need of a master cylinder

A master cylinder is used in hydraulic braking systems of automobiles. The need of using a hydraulic brake over a mechanical brake arises due to many reasons. They are-

  • Due to very high speed of vehicles, the braking force needed to stop the automobiles within a specified distance is much higher. Here the mechanical brakes fail, only hydraulic brakes can provide such a high braking force with utmost safety.
  • The front wheels require more braking force as the mass shift towards the front side of the vehicle during braking. This distribution of force can be done with the use of a master cylinder.
  • A driver typically applies a braking force in the range of 50-70 N. This is not enough for stopping the vehicle. A master cylinder multiplies this force which helps in stopping the vehicle.
  • Master cylinder acts as a converter that is it converts mechanical force applied on the brake pedal to hydraulic force which then is used for stopping the vehicle.
  • The use of master cylinder decreases the risk of failure as it creates independent braking system of front and rear wheels. This way the design is safer in comparison to conventional braking system.

Master cylinder types

Master cylinder can be classified into two types. The classification of master cylinder is done on the basis of number of cylinders used in the braking circuit of the braking system. 

The following are the types of master cylinder-

  • Single circuit master cylinder– As the name suggests it consists of only one cylinder. For example a medical syringe. It uses only one cylinder for braking system. Such type of master cylinder circuit is used in light weighted vehicles such as two wheeler and small four wheeler cars. This type of circuit master cylinder distributes equal amount of braking force to all the wheels as it contains only one cylinder.
  • Tandem or dual circuit master cylinder– In the name it suggests that there are more than one circuits of master cylinders which are used for braking systems. Tandem circuit can be used where independent braking system is required for front and rear wheels. It is used in almost all cars because of its higher efficiency. This is also a safer design for vehicle braking system.

Master cylinder parts

A single circuit master cylinder consists of many parts. We will study about them in the description given below-

Reservoir

The reservoir stores the braking fluid. It is the hydraulic fluid used in braking system. Reservoir is generally made up of plastic.

Cylinder

This acts as a housing for piston. Inside the cylinder, movement of piston takes place. The material used for making cylinder is cast iron and aluminium. The cylinder is connected to reservoir through its inlet valve and to braking lines with the help of outlet valves.

Piston

The piston is the main part which exerts force on the braking fluid. As the brake pedal moves, the piston performs reciprocating motion due to which the hydraulic force is generated. This force is then converted to mechanical force.

Returning spring

It is commonly known fact that potential energy is stored inside a spring when it is deformed from its original shape. This potential energy helps the spring to come back to its original shape. In master cylinder also, returning spring is used for the braking pedal and piston to come to its original position.

Valve

Valve is the outlet portion through which the braking line is attached. The braking fluid is compressed and passes further to caliper through this valve.

Working of a single circuit master cylinder

We shall study the working of single circuit master cylinder in brief. When the brakes are not applied, the the braking fluid does not enter the braking lines.

The braking fluid enters the compression chamber as soon as the brakes are applied. This fluid is compressed due to movement of piston. The braking fluid after attaining a certain compressed pressure, is released to the braking lines due to which the brakes are applied to stop the vehicle.

Working of a tandem circuit master cylinder

The working of both tandem circuit master cylinder and single circuit master cylinder is majorly similar. The only difference between both of them is that in tandem circuit, more than one cylinder is used for braking circuit.

In tandem circuit, after the actuation of primary circuit the secondary circuit is actuated. The braking pressure from first circuit is transferred to the second circuit. This way tandem circuit master cylinder applies braking force from more than one cylinder. It is a safer design for braking systems in vehicles.

Applications of single circuit master cylinder

As the name suggests only one single cylinder is used for braking application in single circuit master cylinder. It is used for light weight vehicles.

The applications of a single circuit master cylinder are-

  • It is used in braking systems of two wheelers like Bajaj, TVS and Apache etc.
  • It is also used in braking systems of various e-rickshaws which are light in weight.

Applications of tandem circuit master cylinder

Tandem circuit master cylinder uses more than one cylinder for braking system.

The applications of a tandem circuit master cylinder are-

  • It is commonly used in all kinds of four wheeler automobiles which are equipped with hydraulic braking systems.
  • Used in heavy duty vehicles because it provides a safer braking application than single circuit master cylinder.
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