Serious Stopping Power: Air Disc Brake Systems for Transit Vehicles

Air disc brakes are rapidly becoming the preferred braking system for new transit vehicles. With their increased stopping control, efficiency, and lower maintenance costs and time, it’s easy to see why air disc brake systems are overtaking traditional drum brakes in the industry.

A Quick Breakdown of Brakes

The advantages of air disc brakes result from the design of the system. Air disc brakes are composed of 4 main parts: a caliper, a rotor, brake pads, and a compressor.

The rotor is a thin disc that rotates with the wheel. The caliper houses and controls a clamping mechanism on top of the rotor. When braking, the caliper applies pressure to the brake pads, slowing the rotor and stopping the vehicle.

The compressor operates two pistons that respond to the operator’s brake pedal and activate the brake. Unlike drum brakes, air disc brakes expose this system to outside air instead of encasing them within a drum.

With their heat-resistant materials and vented design, air disc brake systems have a high thermal capacity, dissipating heat from braking more efficiently than drum brakes. This difference means more braking efficiency and less need for servicing.

A Closer Look at Calipers

The caliper is the heart of the air disc braking system. It is the housing of the air disc brake components and applies the clamping function that stops the vehicle.

Drum brakes use pistons to create friction by pushing brake shoes against a spinning drum and stopping the vehicle. All these components are internally stored in the drum.

Air disc brake systems use pistons to press brake pads against the spinning rotor, exposing these components to the outside air. This design allows for more ventilation, less weight, and easier access for service when compared to drum brakes. For example, caliper brake pad replacement takes only a quarter of the time needed to replace the brake shoes in a drum braking system.

Industry Challenges with Air Disc and Caliper Maintenance

While air disc brakes provide many advantages for transit vehicles, like any moving part, they will require maintenance. Current market conditions have made it especially difficult for maintenance managers and technicians to be ready and responsive to service their fleet. Transit authorities’ most pressing challenges include cost, efficiency, supply chain deficits, quality concerns, and maintenance training.

  • Maintenance costs: When calipers require maintenance, options are limited. Many maintenance managers assume that OEM parts are their only resource. OEM parts are usually more costly, but finding other suppliers is challenging as most do not yet offer air disc brake parts.
  • Limited parts availability: Global supply chain issues have impacted the availability of rotors and calipers. Stock is limited, and finding what you need—when you need it—can be a serious challenge.
  • Quality concerns: Maintenance managers must weigh various quality standards when looking for aftermarket manufacturers. They need to be confident about the quality of critical parts like brake systems.
  • New maintenance knowledge: As newer transit vehicles are equipped with air disc brake systems, technicians require training on their maintenance.

Innovating Aftermarket Solutions

KIRKS Approved EqualTM Remanufactured calipers provide what transit authorities need to service their air disc braking system and keep their vehicles moving.

  • Cost-effective: KIRKS remanufactured calipers have significant cost savings over buying new. Most quality parts are available at less than one-third of the price of new OEM parts. Maintenance managers can confidently stay on budget and keep vehicles moving.
  • Parts in stock: KIRKS has the inventory. Our available stock of calipers and components for air disc brake systems minimizes wait times and gets you what you need when you need it.
  • High-demand parts: The Meritor EX225H2 and EX225H3 and Bendix SN7 systems are also in stock.
  • Quality assured: KIRKS Approved EqualTM remanufacturing process guarantees quality that meets or exceeds OEM standards for performance and reliability. KIRKS also provides samples to transit authorities for testing.
  • Training and Support: KIRKS ToolboxTM provides training for technicians on the installation and proper maintenance of air disc brakes.

Green, Clean, and Pristine

Regrettably, too many cores end up in the scrap bin. While organizations work to find environmentally conscious solutions, their priority must be quality. KIRKS Core Care ProgramTM makes it easy to do both: every shop can go green and have high-quality parts.

KIRKS Core ProgramTM

The KIRKS Core ProgramTM is a quick win.

  1. We coordinate your core pickup
  2. Pay your freight, and
  3. We don’t “nitpick” the condition of the cores to reject or adjust charges.

Remanufactured vs. Rebuilt

Rebuilding processes typically involve cleaning a part and replacing only broken or worn components, even using replacement components from other used parts.

Remanufacturing, however, includes complete disassembly and restoring the product to OEM specifications. Process-driven remanufacturing replaces all critical wear parts and is followed by rigorous testing. Our quality control process and state-of-the-art test equipment ensure that every part we sell with our Approved EqualTM Seal delivers reliability at a competitive price.

Core Before Processing
Finished Unit

KIRKS Remanufacturing Process: A high-level view

Step 1: Core inspection. Our process begins with a complete inspection of a failed core to evaluate its usability and eliminate and dispose of any defective units.

Step 2: Disassembly. Accepted cores are disassembled, and every component is inspected. We do not assume any component is functional for reuse. All critical wear components are immediately disposed of, and only those that meet original manufacturer specifications are accepted for reuse.

Step 3: Cleaning and Qualification. Pressure washing and sandblasting clear debris, rust, and other contaminants. Delicate components are hand-washed. We re-inspect all cleaned components, searching for previously hidden defects and rejecting worn or damaged parts.

Step 4: Cast Cleaning and Inspection. Caliper castings and carriers require controlled burning to remove petrochemicals, followed by shot blasting for soot and other residues. These casts are again fully inspected.

Step 5: Premium Corrosion Protection. Components and casting receive treatment with a rust-preventative powder coating. The powder coating extends the lifetime of each caliper and leaves them looking brand new.

Step 6: Assembly and Testing. Assembly follows the original manufacturer’s specifications, including greasing and lubrication. All critical wear components are 100% new rubber components and bushing and sleeves. Each part is thoroughly tested to assure functionality and within OEM specifications. Our final testing process guarantees proper mechanical function and the highest quality. Finally, each part is serialized and tagged for tracking and warranty.

Remanufactured Caliper Confidence

How does a product earn the KIRKS Approved EqualTM seal? KIRKS Approved EqualTM process means every remanufactured caliper will meet or exceed OEM standards.

As air disc brakes become more common in today’s transit applications, KIRKS is meeting the needs of transit authorities nationwide. With KIRKS Approved EqualTM seal, we make it easy to be confident in the product you buy and that you can get what you need on time and with cost savings. Assurance is in every shipment because KIRKS parts include a 1-year, unlimited-miles warranty.

Stopping Power that Keeps You Moving

Contact KIRKS to request a sample of our Approved EqualTM Remanufactured calipers and learn more about KIRKS ToolboxTM training for technicians. We’ll help you discover how Approved EqualTM products confidently keep your vehicles on the road.


National Distribution Network

Keep your shop fully stocked with a single Purchase Order. KIRKS is a national distributor of recognized brands, and we’ll help you find the parts you need. Register and set up your account today.

Over 75 Years Young

KIRKS is a growing company, 75 years young, serving transit, fleet, and industrial customers. We’re providing new and remanufactured parts to maintenance teams across the country.

We’re proud of the vital work we’re doing to innovate solutions and get reliable parts where and when they’re needed. We support our customers with training, personal service, and reliable parts they can count on.

Our vision is to raise the standard of excellence and be the number one choice for parts in the fleet and transit industries. This is only possible through the outstanding work of the KIRKS team. For three generations, we have stood by our customer services promise: “We’ll take time to do it right—or better—the first time.”