Importance of Drum Brakes in Modern Vehicles

Brakes in a vehicles are one among most important parts of automobile. Currently, most of the modern vehicles use disc brakes that are reliable and efficient but the drum brakes are in the business for the last one century. It was the end of 18th century that both disc and drum brakes were initially used while drum brakes currently used in cars were introduced in 1902.
Drum brakes were relatively cheaper and reliable for vehicles of the past as compared to disc brakes. For most of the time in past, automakers mostly used drum brakes but it depends mostly on type of application. Previously, drum brakes were used for both front and rear application but now these drum brakes are only used in many old and modern vehicles at the rear. Locally manufactured Suzuki Ravi and Suzuki Bolan still uses drum brakes on both sides while several modern models of Toyota still have drum brakes.
As compared to past, the vehicles have become faster which forced the automakers to replace drum brakes with disc brakes on both front and rear. But even then the drum brakes are still in use because they are still reliable.
Following are few of the important reasons that automakers still use drum brakes in vehicles.
Brake Force
As compared to disc brake, drum brakes provide more stopping power and it stops the vehicle relatively quicker because of a large contact patch between the drum and the brake shoe. They provide better braking performance in rainy condition as they are a closed unit and their contact patch remains dry in these circumstances.

Longer Service Period
As compared to a disc pad, a drum brake show can last for double time period. The first reason is that there is 60/40 brake ratio in front and rear brake in disc/drum setup and the rear brake is only applied to stop the vehicle from spinning. Secondly, the drums have relatively bigger friction surface which makes it work far less for applying equal amount of braking. This less force helps the brake to last longer.

Cost
The production cost of the vehicle reduces with drum brakes as they are cheaper as compared to disc brakes. Even today, Toyota offers drum brakes not only in its modern small vehicles but also in trucks like Toyota Tacoma.
Weight
As compared to the rotor and brake caliper assembly, the weight of whole drum brake assembly is less. It can affects performance of car in bumps and humps. The combination of weight of the brake assembly and weight of tyre is called ‘unsprung weight’ that affects the driving and handling of car.

But drum brakes also have few disadvantages.
Overheating
As compared to disc brakes, the drum brakes get overheated on hard brake earlier. The quick overheating of break shoe during extensive breaking is due to the fact that it is an enclosed unit and its contact area is more which makes it difficult to shed the excess heat. In repeated breaking conditions, disc brakes prove superior.
Water Retention
The drum brakes are enclosed unit which helps to keep the water and mud out but if any dirt enters inside the drum brakes then it will badly affect the braking system of vehicle which can result in increasing braking distance to even brake failure. If the water is not drained in time, it can even damage the brake shoes.
Brake Fade
Brake brake fade is commonly seen in drum brakes in extreme conditions. In this phenomena, extensive use devoid vehicles of braking power which can result in even complete brake failure for few seconds. In brake fade, drum and shoes of brake could not slow the car in required time due to less friction. Overheating o r glazing of the drum causes brake fade. This doesn’t affect much to vehicle with disc brakes.
Complexity in Service
It is difficult to adjust drum brakes after service. Adjusting brake bite and replacing the brake shoes are difficult tasks for an inexperienced mechanic. Comparatively, one can easily service disc brakes.

Both drum brakes and disc brakes have their own advantages and disadvantages and they are used in combination for maximizing of their advantages and minimizing their shortcomings.