Physics.edu
Anti-Lock Braking System (ABS)
Written by N.N
Source: http://s3.caradvice.com.au/wp-content/uploads/2013/09/Toyota-Hybrid-Range.jpg
The purpose of the anti-lock braking system is to allow you to stop faster in the case of a car crash. This safety feature allows you to have more control of your car and manouevre it in whichever direction safety is, operating on a stop-start method.
ABS was first developed in 1929, initally for aircraft use before Mercedes introduced the first generation ABS for passenger vehicle in 1970. From there, the development of ABS has been never-ending, with the system becoming more and more efficient each year.
As mentioned before, ABS works on a stop and start method. In the event of a car crash, the driver loses almost all control of the wheel and the car itself. The main response a driver makes in this situation is to put his/her foot on the brakes, which locks up the wheels and causes them to slide or the car to spin out of control. This puts the driver and the passengers at great risk. ABS stops the wheels from locking up when the driver applies the brakes by the repeated process of applying and letting go-release braking pressure for a moment, then provide optimum braking pressure- of the brakes (stop-start method). Each time the car starts, the driver is able to manouevre the car in a certain direction to avoid further collision and each time the car stops, the car's speed is reduced. The work-energy principle states that a shorter stopping distance increases the impact force on the driver and passengers. ABS increases the stopping distance by the stop-start method, ultimately reducing the impact force on the occupants and increase injury protection levels. ABS also slows down the tires to the same rate as the car so that the wheels don't slide too much (when they lock up).
There are four main components to this system: speed sensors, valves, pumps and controllers.
Speed sensors at located at each wheel and decipher which wheel is about to lock up. The information that speed sensors gathers is sent to the controller to make the decision.
Valves are located in three positions: positions 1, 2 and 3. In position 1, the valve is open and it takes the pressure from the master cylinder and passes it through to the brake. In position 2, the valve blocks the line, isolating that brake from the master cylinder so it prevents the pressure from rising further and in position 3, the valve releases this pressure into the brake. The purpose of valves is to allow pressure from the brakes to be released and pressurised. They play an important role in allow the stop-start method occur.
The pump puts pressure back into the valves after the valve reduces the pressure in the line.
The controller watches the speed sensors and controls the valves. It can be reffered to as the ‘brains’ of the whole process.
All these components worl together to make up the ABS system. it is important to note that the ABS system is not a substitue for a driver but is more of an emergency escape option.
