Airbrakes are used on semi spans to increase drag, which helps to slow down the vehicle and reduce its speed. This is especially important for large trucks and trailers when navigating steep or winding roads.
The airbrake system on a semi span works by using compressed air to activate the brakes on each wheel. When the driver pushes the brake pedal, the air compressor releases air to the brake chambers, which pushes the brake pads against the wheels, creating friction and slowing down the vehicle.
The drag increase with airbrakes is affected by several factors, including the size and design of the airbrake, the speed and weight of the vehicle, and the wind conditions. The angle of the airbrake and the shape of the semi span's body can also impact the amount of drag increase.
The drag increase with airbrakes can be calculated by using the formula: Drag = 0.5 x ρ x V² x Cd x A, where ρ is the air density, V is the velocity of the vehicle, Cd is the drag coefficient, and A is the frontal area of the semi span.
While airbrakes are an effective way to increase drag and slow down a vehicle, they can also cause increased wear and tear on the brakes and tires. Additionally, airbrakes can be less effective in wet or icy conditions, so it is important for drivers to still use caution and proper braking techniques when using airbrakes.