ABS defined in simple terms - How is it different from CBS?

 " ABS and CBS working mechanism and how it can save lives? "

CBS: Combined Braking System

Let's begin with CBS as it is easier to understand and the term itself is self explanatory. 

CBS or the combined braking system is the name given to any braking system in two wheelers wherein if the rear brake is pressed the front brake gets applied automatically. 

CBS was launched by Honda and different companies use it by different names.

for eg: Suzuki prefers CBS but Yamaha named it UBS(Unified braking system)

different names- works same

the below diagram will help you understand the mechanism even with more ease:

what's happening here: In CBS an equalizer is set up with the rear brakes. The operation of the right lever applies the brake on the front wheel only but when the left lever is pressed, the rear brakes are applied and in some ratio the front brakes are applied as well. The combined braking ratio is different for different companies. For instance whenever I apply the rear brakes on my Suzuki Burgman scooter which has a 125cc engine, 30% of the front brake is applied as well. 

How does CBS helps: One thing to take note is CBS is completely different from ABS and CBS only assist in distributing the braking force between the front and rear wheels and UNLIKE ABS DOES NOT PREVENT THE WHEELS FROM LOCKING.

Most effective way of braking is to apply the front and rear brakes simultaneously with more braking pressure at rear brakes and comparatively lesser pressure at the front brakes. However, this only comes with proper practice and knowledge and takes time to master. Also at times of emergency or sudden braking we tend to panic and apply only the rear brakes subconsciously out of practice and that's where CBS comes in play. In emergency situations when we tend to apply only rear brakes, CBS will automatically engage the front brake in some ratio and helps in keeping the bike/scooter stable and also reduce the stopping distance by a little margin because both brakes are applied instead of one gradually reducing the stopping distance. If one applies both brakes manually, CBS has nothing to do with stopping distance.

CBS technology is a great boon for amateurs and newbies learning to ride. It will be of Zero use once you start applying both brakes simultaneously. It's always good to practice using both brakes in even minor braking scenarios as it will not only help you master proper braking techniques but also help you in applying both brakes in emergency situations.

Let's move on to ABS now. Before proceeding, you should keep this in your mind that CBS is nothing but a simple link between front and rear brakes wherein applying rear brakes will also apply your front brakes in some ratio and has nothing to do with reducing stopping distance or preventing locking up of wheels. 

ABS is completely different and here how it works

ABS: Anti Lock Braking System

In simpler terms,  ABS prevents the wheels from locking due to sudden braking. 

CBS can work with any brake setup like drum, disc or drum and disc combination but ABS works only with Disc brakes.

How does ABS works: ABS is a very complex system and it's very important to understand the working mechanism behind to able to understand the use of ABS.

have a look at the below diagram:

In bikes/cars without ABS when disc brakes are applied, hydraulic fluid from the reservoir goes to the caliper body where the piston gets operated and squeeze the brake pads, hence stopping the vehicle. (as in above diagram)

ABS system consists of two main parts, namely HCU(Hydraulic control unit) & ECU(Electronic control unit)

The hydraulic fluid line instead of directly going to the brake's caliper body goes via HCU which is connected to ECU.

The ABS system includes speed sensors attached to the wheels which is monitored by ECU.

In normal braking where no locking up of wheels is detected, brakes are applied normally. 

Since ECU has speed sensors monitoring the speed of the rotation of the wheels.  The moment ECU detects that the wheels are stopping at an alarming rate and is about to lock up, the ECU unit sends information to HCU which comes in play and stops supplying hydraulic fluid to the brake pads and the brakes are released and the wheel is allowed to spin intermittently and thus prevents locking up of wheels. Once the ECU detects that the wheel is not locking up, It sends signal to HCU to reapply the hydraulic fluid to reinstate the braking force.  The above step gets repeated number of times within seconds to provide best result.

go to below YouTube link to understand even more thoroughly how Anti-Lock Braking System works

Animated Video - How ABS works by Ajith Buddy.

We saw how ABS prevents locking up of wheels. And please don't be surprised if I tell you despite of this fact that it overrides manual braking and release brakes even though momentarily, ABS still helps in REDUCING STOPPING DISTANCE. period!

How?

very simple. During braking without ABS, sliding friction comes into effect and the tires slips, increasing the stopping distance, however in ABS braking the ECU unit after monitoring the speed adjust the brake pressure to keep the slip ratio to minimum. This significantly reduces the braking distance.

I hope I was able to explain the basic fundaments involving ABS & CBS

Feel Free To Comment  if you have any doubt...