What should the brake pipe pressure and straight air pipe pressure be, respectively, before moving a car?

The correct response indicates that the brake pipe pressure should be 90 psi, while the straight air pipe pressure should be 70 psi before moving a car. This setup is essential for ensuring that the braking system operates effectively and safely when the train is in motion.

Brake pipe pressure is crucial because it controls the train's braking system and ensures a proper response when the brakes are applied. A pressure of 90 psi indicates that there is adequate air supply to the braking system, allowing for reliable performance and the ability to bring the train to a stop when needed.

The straight air pipe pressure, set at 70 psi, relates to the auxiliary air systems that can provide supplemental braking force. This pressure is significant for enhancing the actuation of the brakes and providing additional safety measures, particularly during instances when fast and effective braking is required, such as emergencies.

Maintaining these specific pressures helps prevent issues such as insufficient braking power or system malfunctions, which could compromise safety. Correctly set pressures foster a reliable interaction between the braking systems when the train is in operation, allowing operators to move with confidence that the train will stop safely when commanded.