(a) Parking brakes.--Every vehicle or combination, except a motorcycle, operated on a highway shall be equipped with a parking brake system adequate to hold the vehicle or combination on any grade on which it is operated, under all conditions of loading, on a surface free of ice or snow. The system shall not be designed to require a continuous or intermittent source of energy for full effectiveness after initial application.

(b) Service brakes.--Every vehicle and combination operated on a highway shall be equipped with a service brake system adequate to control the movement of and to stop and hold the vehicle or combination on any grade on which it is operated, under all conditions of loading, and adequate to meet the braking performance standards established by regulation of the department.

(c) Breakaway systems.--Every combination operated on a highway, the towed vehicle of which is equipped with brakes or which has a gross weight in excess of 3,000 pounds, shall be so equipped that, upon breakaway of the towed vehicle, the towed vehicle shall be stopped and held automatically, and the towing vehicle shall be capable of being stopped and held by use of its own service braking system.

(d) Exceptions.--This section does not apply to towed instruments of husbandry and such items or types of special mobile equipment or commercial implements of husbandry as are specifically exempted from compliance by regulations promulgated by the department.