The parking brake in vehicles with air brakes is applied using:
a.The brake pedal
b.A yellow diamond-shaped push-pull control knob
c.The trailer hand valve
d.A foot-operated lever
Explanation
In vehicles with air brakes, the parking brake is controlled by a yellow, diamond-shaped push-pull control knob on the dashboard. Pulling the knob out applies the parking brakes (spring brakes), and pushing it in releases them.