Trucks and heavy motor vehicles carrying a heavy payload of 10 tons and above need tremendous stopping force. Hydraulics simply cannot deliver the torque necessary to bring such a heavy vehicle to an abrupt halt at short distances. But Pneumatic Air Brakes can and this is the reason they have been in widespread use in heavy trucks and heavy vehicles since the 1920s. One prime consideration is that air brakes are fail safe.
A further development was incorporation of antilock braking system during the 1960s.
Within these categories there are different types of pneumatic air brakes such as:
The method of actuation may differ. Some pneumatic brakes are the spring return type while others are spring actuated.
Pneumatic or compressed air brakes have two main sections.
Air Brake Activation is through the foot pedal. The parking brake may be hand operated.
Operation of pneumatic brakes is simple.
The third stage is release in which increased pressure lead the triple valve to vent air to the atmosphere and recharge the storage cylinder with air.
In comparison to advantages, especially to stop heavy vehicles, disadvantages are few: