Brakes: The General - Part1

In these series of blogs, we are gonna discuss everything and anything about brakes, starting from terminology and basics involved in first blog to its calculations and how entrepreneur designers can design their own locomotives. Since Brakes are one of the most important 3 mechanisms of any locomotive, other being power generation and steering mechanism; So, we will give time and explain everything about them gradually! So, let's start with the basics! What is a brake? In easiest words, a system or device that reduces or halts motion. Taking example of cars; brakes reduces the speed of a moving car and eventually brings it to a complete halt. Now, there are various types of braking methodologies, 1) Friction Brakes: The brakes use friction to bring out braking action and usual example include drum brakes, disk brakes, hydraulic disk brakes & pneumatic disc brakes. 2) Pumping Brakes: which use engine and engine's components friction as the required braking action! The most popular ans simple type of Pumping brake is Jake Brake which open the exhaust valve during the expansion stroke of Engine. 3) Electromagnetic Brakes: They bring about the braking action using electromagnets, they are commonly installed in hybrid/electric vehicles and is also the basis of KERS (Kinetic Energy Regeneration System) in cars. 4) Drag Brakes: These types of brakes find their application in vehicles which require deceleration through a fluid medium like air or water; the easiest example is the flaps in the wings of aircraft.

courtesy to www.images.google.com

The above image shows a typical disc-drum arrangement in a modern car and the various components involved in them! In the continuing articles we will explain functioning and detailed information about each component but for basics, I believe, its the best way to understand the braking system. Now, let's talk about some terminology one should know while studying brakes.

1) Peak Force: The peak force is the maximum amount of decelerating effect that can be achieved by the system. The peak force is usually greater than the traction limit value of tyres which results in wheel skid when brakes are applied with full force. The peak force depends on the friction coefficient between the friction components of the braking system and the time of actuation or in drag brakes case: the angle of attack i.e. at which angle the actuated component is to the streamlined fluid.

2) Continuous Power Dissipation: It is commonly affiliated with friction brakes, on actuation a lot of heat energy is produced in the system and after a particular temperature the braking system might breakdown! Thus, the maximum amount of power a braking system can dissipate without breaking down is called as Continuous Power Dissipation. The dissipation is dependent on temperature and speed of ambient cooling air.

3) Brake Fade: Because of increase in temperature, the brakes efficiency might reduce, which is technically termed as Brake fade. It is dependent on the design, and cooling system of brake plays a very important role in determining the Brake Fade of the system.

4) Smoothness: It is more of a physical term than technical term for brake application. It's all about the experience of the driver, if the brakes are harsh, worn out and exert unequal force will produce skids and would be unappreciated by the driver as such system will make him experience that he is driving on a camel.

5) Power: It is the amount of brake force the system produces with respect to the application of brake pedal! In other way, it is the ability of the system that how fast can it reach its Peak Force.

6) Drag: It is the incomplete detachment of one braking component with another because of which the unwanted braking action might be there even during full pedal release. The common causes of drag are misaligned brake shoes, broken springs, over-extended actuator wire or piston failure etc.

7) Durability: Brake systems have frictional parts that wear out at every application of brake and might needs to be replaced from time to time. The durability of systems with higher peak force is lesser.

Well, these are the most important terminology one must know in order to understand braking and braking systems! The braking system is specifically mounted on either wheel or trans-axle depending on application of the braking system. One thing that one must also know is that braking system which may/may not include supporting structure adds into weight of the body thus, it also plays an important factor depending on application. With this, we end our first article on basics of brakes and keep tuned for the next article which will briefly explain each component of braking systems and application-wise differences in them.