Air-over-hydraulic brake systems operate using a combination of compressed air and hydraulic pressure, and the release of the air and hydraulic pressure engages the master cylinder. It then applies pressure to the valves, and the brake fluid is released. The brakes then exert friction on the tires, which stops them.
Air-over-hydraulic brake systems contain an air-over-hydraulic power cylinder. This cylinder has both an air cylinder and a hydraulic cylinder inside, which work in tandem with each other. The air and hydraulic cylinders each contain a piston and common rod. The air cylinder's piston is a larger diameter than the hydraulic cylinder's piston. This results in greater hydraulic pressure being released during normal breaking. When the brake pedal is pressed, the valves are opened by the master cylinder, releasing the atmospheric pressure that builds up when the valves are closed. During hard braking, the master cylinder causes greater valve movement. This results in the valve releasing more air into the air-over-hydraulic power cylinder, allowing for faster braking.
Most modern vehicles have two-circuit brake systems, which are operated by the master cylinder. Each circuit controls two wheels. This increases safety because if one circuit fails, drivers can still brake as long as the other circuit remains operational.Learn More
To add brake fluid to a vehicle, clean the reservoir cover, open the reservoir, check the fluid level and fill the reservoir to the indicated level. If the vehicle is equipped with an antilock braking system, check the owner's manual for special instructions before opening the cap.Full Answer >
A disc brake uses a set of calipers to press braking pads against a disc attached to the wheel. The friction from this contact slows the wheel and, by extension, slows the vehicle. Most cars have disc brakes attached to the front wheels and older drum brakes on the rear, while some have disc brakes on all four wheels for maximum control.Full Answer >
A problem with the brake disk rotors is the most common cause of vibration when braking at high speeds. Rotors are circular metal parts found behind the wheel of the vehicle that the brake pads press against to create friction and stop the vehicle. Small irregularities in the rotors transfer to the steering wheel when applying the brakes. Another cause of vibration is improperly tightened lug nuts.Full Answer >
While disc brakes tend to last anywhere from 30,000 to 50,000 miles, the length of time brake rotors typically last depends on several different factors. These factors include how often the brakes are applied, how hard they are applied, the weight of the vehicle and how often the brakes have been serviced.Full Answer >