CDL Vehicle Combination Practice Test

What is a characteristic of semitrailers made before 1975 that are equipped with air brakes?

1. They always have spring brakes

2. They often do not have spring brakes

3. They have automatic brake systems

4. They require no inspection

The correct answer is: They often do not have spring brakes

Semitrailers made before 1975 that are equipped with air brakes often do not have spring brakes. This characteristic is important because spring brakes are typically a safety feature designed to act as a backup braking system in case of a failure in the air brake system. In older models, the technology and standards for air brakes were not as advanced as today, and many did not include this essential safety feature. Vehicles built after 1975 saw significant changes in safety standards, requiring the inclusion of spring brakes to enhance the safety of the trailer when the air system fails. Therefore, understanding the design differences between older and newer semitrailers is crucial for drivers, especially in terms of safety and compliance with regulations. This awareness helps ensure that adequate measures are taken when operating older equipment.