If a Comeng is powering from the rear, how will it operate?

When a Comeng train is powering from the rear, it is essential to address the situation properly for safe and efficient operation. The correct choice here involves turning the red emergency cock, which is a critical safety feature. This action allows the driver to engage and enable train power or braking systems manually, ensuring functionality in a rear powering scenario.

The red emergency cock is specifically designed for such circumstances, enabling operators to control power and safety features directly. This manual intervention becomes necessary, especially if the automated systems fail or if the train's operations need to be conducted outside of the typical control mechanisms in place.

Other methods listed involve automation or centralized control systems, which usually are intended for standard operation scenarios and may not provide direct manual intervention needed when the train is powered from the rear. Thus, engaging the red emergency cock is the appropriate safety procedure to ensure the safe management of the train in this specific situation.