WABCO India’s Air Disc Brake To Improve Safety, Profitability

By T Murrali :

One of the major advantages of autonomous driving will be reduction in accidents and fatalities. Globally about 1.3 million people die in road accidents every year, almost 3,200 deaths daily. Another 50 million people are injured or disabled. India accounts for one-eighth of the fatalities. One of the possible reasons is the failure or non-effectiveness of brakes, especially in the commercial vehicles. Most of the brake system suppliers have been introducing new technologies like Air Disc Brake (ADB) to ward off this.
WABCO India, which designs, manufactures and markets conventional and advanced braking products and systems, is test-marketing ADB in the commercial vehicle segment here. This technology has been with its parent company, the US-based WABCO Vehicle Control Systems, for more than two decades.
“We are in talks with a few more OEMs in India to supply ADB and when the volume picks up, we will begin commercial production,” P Kaniappan, Managing Director, Wabco India, told AutoParts Asia.
In the developed markets of Europe ADB has 85 percent penetration. In the US it has 15 percent and by 2021 it is expected to be 30 percent. In China it is used in eight percent of vehicles and in five years it is envisaged to cross 35 percent. In India ADB application is less than one percent. “We expect it to grow at least to 10 percent by 2020; we see it as a great growth opportunity here. We are working on introducing ADB to the bus segment and to the entire range of light and heavy duty trucks. We are testing it on more than 20 vehicles right now. The drivers and fleet owners are giving their feedback and experience in using it. They say there is much better balance in braking, better safety and durability. SRS Travels and Orange Travels have been using ADB in some of their buses,” he said.
At present the company is testing it on the buses as ADB has already beenapproved by our OE customers. It will be put on commercial sales in a matter of months. Fleet owners have given a clear testimonial that pad change time has reduced, pad life has almost doubled, downtime is less and overall vehicle utilisation has improved. They have run it for more than a million kms during the last one year. All the validation tests have been completed by the OEMs, he said. In India the cost of ADB is set to be amortised in six to eight months. Kaniappansaid, the OEMs work with the axle makers to introduce ADB. “As long as the customer has released the drawing and it is homologated, we can do it. It is possible for retrofit in the current models provided it is released by the OEMs; they have to release the hub design as it is central to the axle. Once this is done retro-fitment can be completed by integrating the hub with our system. In some cases the fleet owners do the job,” he said.
With laws governing over-loading becoming more stringent in India, customers would be looking at reducing vehicle weight. This is one of the most important value propositions from the fleet point of view. Weight reduction covers the full range proportionately, from HCV to the light duty segment. In Delhi, DTC runs more than 2,000 buses with front-wheel ADBs since a few years and they are quite happy with the product. That would have triggered the government to make it a required specification. It will come soon in many of the OEM platforms, he indicated.
“By 2018 we will have a local assembly line in India. Currently we import, from our low cost manufacturing facility in China and from Manheim, Germany. We need certain volumes at competitive cost, which is why we will localise,” Kaniappan said.
Sven Horak, Vice President, Business Unit Leader, Wheel End Solutions, WABCO, said, “Our focus is to not only increase safety but reduce costs and to be prepared for future technologies. We are the pioneers of the single piston ADB technology which is robust, proven and readily available in the market; we are convinced that this is superior to the double piston air brake. We supply ADB not only in Europe but also in US, Brazil, China; recently we have entered into Japan.”
The global conglomerate has five manufacturing locations in four continents with more to come. Its manufacturing footprint for wheel-end products also includes piston type actuators, brake chambers, double actuators as well as automatic slack adjusters. I
n Europe, the competent centre for ADB is in Manheim, Germany, and the second plant is in Poland. In the US where the penetration of this technology is significantly increasing, the latest addition is in Charleston. It has significant presence in Brazil and China. In India it has four manufacturing facilities to offer the wheel-end products. The company will soon enter Mexico, he added.

ADB Advantages

There are four key parameters that differentiate ADB from drum brake technology – safety, service, comfort and cost. Shorter stopping distance, constant brake performance and very high mechanical efficiency, are the main attributes of ADB and are sought after by the fleet operators across the globe.
While the braking efficiency is paramount the prime advantage of ADB is in weight reduction; the single piston allows to deliver the same performance with significantly lower number of components, which in turn minimises parts failure. ADB has only 18 components while the conventional drum brake has 39 parts. Overall it reduces the weight – about 25kg per wheel-end or 50kg per axle – with the result that efficiency increases. The lower weight results in lower fuel consumption. Since the design is more compact the need for the envelope or the space occupied in the vehicle is smaller. This gives the OEM the freedom to design its chassis and axles in a better way.


The ADB has been tested and proved to deliver improved performance on any type of road under all weather conditions with the highest level of consistency, irrespective of driving up or down hill. The brake pads last twice longer than drum brake linings and so the changing cycle is reduced. Besides, the time to replace the pads is also less; for instance to change the brake linings in a drum brake system takes four times longer than changing the brake pads of an ADB. So the downtime for the fleet is considerably lower. All these prove that ADB technology is much superior to drum brakes.
ADB offers driving comfort similar to the passenger car brake. Though the cost is higher, it is lower from the installation point of view as it is a plug and play system. The patented single piston technology with less number of parts, can be effective only when the callipers move freely. Yet another advantage is that unlike in dual-piston technology that needs synchronisation of two pistons to get equal force, single piston does not need that. ADB’s fully encapsulated system ensures that the grease is not washed away besides preventing abrasive materials like sand or mud entering and damaging the sliding function of the calliper. The company uses an optimised pad design that has reduced the width of the brake and made it thicker by two mm; this increases the life of the brake by 10 percent.
The company has also patented its ‘spreader-plate’ (taper wear compensation) to prevent the brake pads from wearing out unequally; spreader-plate enables the braking force to spread uniformly over the pads. ADBs come with automatic correction and a bi-directional adjustment mechanism as compared to other brakes that can only be adjusted in one direction – resulting in hot runners as friction and temperatures increase. There is a clutch in the adjuster mechanism that works in both directions and it continually ensures the air clearance of 0.7mm.

ADB Evolution

ADB is currently used in Europe in light and medium trucks, and buses. It is used in China where the company manufactures it locally and also in the US where it is used for trade applications; this brake technology is available for both truck and trade applications.
“We have delivered several millions of these brakes to the field for use in any kind of application. In 2010 we introduced the Max technology equipped with a continuous wear sensor to get full benefit from EBS (electronic brake system) technology. All in all, we are well prepared to deliver to Indian OEMs and customers – we have the solutions for whatever is required. In Europe the ADB costs less than the drum brake; ADB penetration there is 85 percent. The situation in the Indian, Chinese and US markets is slightly different because of the presence of specialised foundation brake manufacturers. So it is not a question of outsourcing it but one of how much costs the OEMs are able to digest to get this superior technology on board. We have worked on it for more than seven years to bring down the cost to a level that allows a payback of less than one year. It makes sense, therefore, for fleet owners to introduce ADBs so as to reduce the total cost of ownership,” Horak said.
OEMs are now moving to advanced emergency braking systems. With autonomous driving coming in, the need for effective braking is very high. The ADB is a more suitable solution for that. “In the Max range we are continually monitoring tread wear. When you have telematics or electronics braking system, it can take in all input from EPS and fleet management to feed out data continuously,” he said. On the parameters that could influence new technologies like ADB in India, Kaniappan said, “The first one is regulation; the government is quite serious about it as BS-VI date is finalised. There is a serious discussion on scrapping of 15-year old vehicles, fuel efficiency norms, etc; lots of things are coming in. All this will drive new technologies that we can leverage to present new solutions wherever required. Indian customers are now testing and evaluating some of the advanced emergency braking systems for collision avoidance, which immediately assists and alerts the driver. ADB is of immense use here as the stopping distance becomes critical. The other route is to use these new technologies to help customers get some advantage from it like better fuel efficiency, more tyre life and comforts like hill-assist features, automatic traction control and others.”
A drum brake does not deliver the same performance at any point of time as ADB. During running, the emergency assist or automatic braking system has to know what kind of performance is available at a particular point, to calculate the deceleration and the pressure that needs to be brought into the system to stop the truck in time. This is possible with ADB.
Autonomous driving is one of the global megatrends today, the other one is electrification. In India, hybrid vehicles are already being produced; so there is a strong focus to move into electric vehicles where costs could come down. The third dimension is connectivity – digital transformation of connected vehicles. Effective fleet management would be one result area; we are supplying a fleet management solution that can connect and communicate with all the sensors to enable monitoring of the various systems in the vehicle. Remote diagnostics and predictive maintenance would follow.
One of WABCO’s associate companies, Transics, is working with many fleet owners, enhancing support to the systems available there. The whole model will move towards remote diagnosis of the customer’s problem, which will be resolved in a predictive maintenance mode, so that the system is not allowed to break down. “We are already partnering with a few OEMs in India on this. One of them has already nominated us as an OE supplier,” Kaniappan said.

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