True or False: You should check for air at the rear of the second trailer by opening the emergency line.

The statement is true because checking for air in the emergency line is an important part of ensuring that the air brake system is functioning properly across all trailers in a doubles/triples configuration. By opening the emergency line, you can determine if there is an adequate supply of air pressure reaching the rear trailer, which is crucial for the operation of its brakes. If the second trailer does not receive proper air pressure, it could lead to brake failure, posing a serious safety risk.

Ensuring that the brakes on all trailers are operational is vital, whether they are empty or loaded. The fact that air pressure is essential for proper brake function is the reason that this check should not be limited to empty trailers or reserved only for emergencies. Regular checks contribute to safer driving conditions and compliance with regulatory requirements regarding the operation of multi-trailer combinations.