To reduce application pressure to the steering axle brakes during most braking situations.
Reduced pressure to the steer axle brakes occurs for most braking applications.
Only during hard braking is there equivalent pressure delivered to both the front and rear brakes.
Up to a 40psi (275kPa) service brake application, the air pressure delivered to the steer axle brakes is 50%.
During emergency braking (high application pressure 60-70psi (414-482kPa) braking, full application pressure is delivered to the steering axle.
During emergency braking of more than 20psi (130kPa), it is imperative that you have your seat belt fastened, otherwise you are going to be doing a “bug impression” on the inside of the windshield.
Questions on test: At what pressure is there equal braking to the front and rear brakes?