How do the emergency brakes on a trailer typically function?
a.They are applied by electrical signals from the tractor
b.They use spring force that engages when air pressure is lost
c.They are manually applied by pulling a cable
d.They use hydraulic fluid from the tractor
Explanation
Trailer emergency brakes use powerful springs that are held compressed by air pressure during normal operation. When air pressure drops due to a leak or disconnection, the springs expand and push the brake shoes against the drums to stop the trailer.