Air-over-hydraulic braking systems use compressed air to power a hydraulic brake system, primarily found in medium-duty commercial vehicles. This combination provides enhanced braking power, leveraging the benefits of both air and hydraulic systems.
How Air-Over-Hydraulic Brakes Work
Air-over-hydraulic systems essentially act as an amplifier. Here's a breakdown of the process:
- Air Compressor: An engine-driven air compressor builds up compressed air in reservoirs.
- Air Pressure: When the driver presses the brake pedal, it activates an air valve.
- Master Cylinder Activation: The compressed air then acts on a hydraulic master cylinder.
- Hydraulic Pressure: The master cylinder generates hydraulic pressure, which is then transmitted through brake lines to the wheel cylinders or calipers.
- Braking Action: The wheel cylinders or calipers apply the brakes, stopping the vehicle.
Advantages of Air-Over-Hydraulic Systems
- Increased Braking Power: Compressed air significantly increases the force applied to the hydraulic system, providing more powerful braking, especially for heavier vehicles.
- Improved Control: The air assist allows for finer control over braking force, enhancing driver control.
- Reliability: The combination offers a reliable braking solution for commercial applications.
Key Components
The main components of an air-over-hydraulic system include:
- Air Compressor
- Air Reservoir(s)
- Brake Pedal Valve (Air Valve)
- Air-Hydraulic Power Unit (Master Cylinder)
- Hydraulic Brake Lines
- Wheel Cylinders or Calipers
Licensing Requirement
It is important to note that in some jurisdictions, like Ontario, Canada, drivers operating vehicles equipped with air-over-hydraulic brakes may require an air brake endorsement on their driver's license.
Summary
In summary, air-over-hydraulic brakes are a system designed to amplify braking force using compressed air to actuate a hydraulic brake system, commonly used in medium-duty commercial vehicles requiring significant stopping power.
