What is the required main reservoir pressure for freight locomotives?

The required main reservoir pressure for freight locomotives is critical for ensuring proper operation of the air brake systems. The determination of 120 to 140 psi as the correct range ensures that there is enough air pressure to effectively operate the locomotives' braking systems, which are essential for safety and performance when hauling freight.

This pressure range provides a balance between adequate power for braking while preventing damage to the system that could occur with higher pressures. Maintaining this specified pressure is vital to ensure compliance with industry standards and operational guidelines, thereby enhancing the reliability of the freight operation and minimizing the risk of brake failures during transit.

The other ranges fall outside the optimal pressure needed for freight locomotives, either being insufficient for effective braking or potentially compromising the integrity of the brake system. Understanding this pressure requirement helps ensure safe and effective operation of the locomotives on the rail network.