What service braking is actuated by the primary circuit on a typical tandem drive axle,air brake equipped tractor?

A) front brakes
B) drive axle brakes
C) emergency braking only
D) all tractor axles

Primary Circuit

The main electrical circuit in a system, responsible for providing power to the essential components or functions.

Tandem Drive Axle

One of a pair of drive axles used in tandem drive highway trucks.

Air Brake Equipped Tractor

A tractor fitted with a pneumatic brake system, utilizing compressed air to create braking force for the vehicle.