ABS was first developed in 1929 for Aircraft systems and the technology was later implemented in the four-wheelers in 1966. The main scale implementation of ABS didn’t see the light of day till the mid-1980s. ABS stands for the anti-lock braking system and the technology does exactly what it is named after. ABS prevents the wheels from locking up and thus avoid uncontrolled skidding of the vehicle and also reduces the travel distance without slipping of the wheel once you slam your brakes.
This system is all the more essential at higher speeds and on the highways where a major difference can be noticed. ABS has little work to do when in city riding conditions that greatly restrict the upper limit of speed. Another situation that helps us appreciate the beauty of ABS is during monsoon. Cars cruising at such high speeds on a weather with little traction is a perfect situation where ABS plays the most effective role. A car without ABS is bound to start skidding when the grip on the road is less, this is mainly because the wheels of the car abruptly stop spinning and this makes you lose control over the car resulting in a dire situation with little you can do.
ABS takes this issue out of the scene and prevents your wheels from locking up even when you slam the brakes hard. In this article, we’ll be explaining what ABS is and how it actually works.
What is ABS in Cars and Bikes?
As talked about above, ABS stands for Anti Lock braking system which is a safety system in cars and other automobiles that prevents the wheels form-locking up and helps the drivers maintain their control on the steering wheel. This is also referred to as the anti-skid braking system by a few and it helps the wheels of the vehicle to the main traction with the ground to avoid uncontrolled skidding. ABS gives you more confidence in situations where sudden breaking is required.
Principle of ABS
The principle that ABS is based on is very simple to understand, the task of ABS is to offer improved vehicle control by preventing the wheels from locking up and thus avoid skidding.
A skidding wheel tends to have less traction as the tire patch that is in contact with the road is sliding, to avoid this, ABS controls the brake fluid pressure, independent of the pressure being applied on the brakes. This helps avoid the slipping of the wheel each time it gets locked by bringing the speed of the wheel back to the minimum slip level that is required for optimal braking performance.
Components of ABS
ABS is essentially made up of four main components.
The speed sensor is attached to each individual wheel that is ABS enabled and monitors the speed of each wheel to determine the locking of the wheel and decide whether a specific acceleration on braking is required for that wheel. The speed sensor is made up of an exciter which is a ring with V-shaped teeth on it and also a wire coil with magnet assembly. This helps generate the pulse of electricity as the teeth pass the exciter in front of it.
Valves are a part of the regular braking system too, they are used to regulate the about of pressure on the brakes when ABS is put to work. THere is a valve in each brake that is controlled by ABs and in the first position, the brake valve is open, allowing for the pressure from the master hydraulic cylinder to be transferred to the brakes in order to actuate them. When the speed sensor detects a slip, the valves are closed and the pressure from the master cylinder is contained and once the required effect is achieved, the valve again releases some of the pressure on the brakes. These steps are repeated till the car comes to a complete halt. If you notice, there will be a minute resistance while braking at high speeds and this is the brake valve controlling the pressure that is being transferred to the brakes from the master cylinder.
Electronic Control Unit (ECU)
The ECU or the Electronic Control Unit is the essential part of the ABS system that receives, interprets and amplifies the sensor signals to calculate the wheel rotation speed and slipping. The ECU receives a signal from the sensor in the wheel and uses this data to control the brake pressure accordingly.
The Hydraulic Control Unit is powered by the ECU and receives signals to apply or release the pressure on the brakes under the anti-lock basis. The Hydraulic Control Unit modulates the brakes by increasing or decreasing the hydraulic pressure and bypassing the pedal force to reduce the braking power.
Working of ABS
When the brakes are applied if a wheel-lock situation is detected by one of the speed sensors on the wheels, the ECU sends a signal to the HCU to release the braking pressure and prevent slipping of the wheel. This results in an increase in the wheel speed and results in the decrease of wheel slip. When the wheel velocity increases as a direct result of reduced braking, the ECU then sends a signal to the HCU to reapply the braking pressure on the wheels and this helps reduce the wheel sleep to a decent amount. The Hydraulic Control Unit in the ABS system controls the braking pressure in each cylinder associated with the wheel based on the signal that it receives from the system sensor. This process is repeated to control the wheel speed till the car comes to a standstill or till the brake pedal is released.
Based on the number of individual sensor and type of brake used, the ABS is classified into different types.
This is the best and the most effective type of ABS system and there is a speed sensor in each individual wheel and a separate valve controls the braking pressure of each of the four wheels. With this setup, the ECU monitors each individual wheel for the speed and slipping, this ensures in achieving maximum braking force.
This is commonly seen on pickup-trucks and other lost cost implementations of ABS. In the Three-channel system, there is a speed sensor and a valve to control each of the front wheels and a single valve-sensor combo control the rear wheel setup. This reduces the control on each individual rear wheel, but as the sensor is connected to the rear axle, it does end up providing similar results. There are also two-channel and one-channel ABS system, but they are mostly deprecated and rarely found on vehicles these days.
Does ABS help stop the car faster?
Contrary to the belief, ABS doesn’t generally help stop the car faster, rather it helps stop the car more reliable manner. ABS works more to maintain better control of the car under hard braking in two ways, firstly by stopping the car from skidding with all the wheels locked and secondly by allowing you to steer the car while braking without losing the traction. This helps you steer away and avoid hitting the object that caused the panic braking in the first place.
Cornering better with ABS
car manufacturers now use ABS to help their cars to corner safer and faster. This is done by using ABS in the car as a traction control and as a chassis stability aid. This essentially lets the car detect when the car is in danger of losing control over a steep turn and subtly applies the brakes on one or more brakes to gain control. In a recent experiment by Saga, it was found to be greatly helpful while maneuvering an ABS car with the traction control turned off, the driver claimed to have hit the cone in a very short span despite the speed being just 40kmph. With the Traction Control turned back on, the car was able to go past all the cones without any issue, although a drastic automatic reduction in speed was seen while steering hard.
ABS in Windy Situation
Most modern cars implement high-end technology to overcome most of the difficulties that were previously seen, one thing they couldn’t help avoiding is the effect of crosswind on the motorways and highways. This is not common in the case of Trucks and even pickup trucks in most cases as the weight of the heavy vehicles acts as an effective sail in heavy winds, while extreme conditions can still hinder the experience, it is very much unusual.
We’ve seen few manufacturers including Mercedes Benz use the ABS fitted in their cars to control this movement that is a result of windy conditions and apply brakes to the required wheel helping regain stability of the vehicle.