What is the minimum PSI required on the rear car during a Class III Brake Test?

The minimum PSI required on the rear car during a Class III Brake Test is 75 PSI. This requirement ensures that the brake system is functioning properly and can effectively hold the train in place. During a Class III Brake Test, an inspection verifies that the brakes are able to meet operational standards, focusing particularly on the capacity to create adequate air pressure for effective braking. Having at least 75 PSI guarantees that the brake system on the rear car has sufficient pressure to operate safely and reliably, which is crucial for both the stability of the train and the safety of its operation. Lower pressures may not provide the necessary braking force needed in case of an emergency, therefore, 75 PSI is established as the minimum standard to ensure adequate braking performance.