What manual operation is required on a DM car after a MR leak is detected?

When a main reservoir (MR) leak is detected on a DM (Diesel Multiple Unit) car, it is crucial to take prompt manual action to ensure safety and functionality. The correct procedure involves manually releasing the parking brake (PB) using the manual release device. This step is essential because a leaking MR can lead to insufficient air pressure necessary for the operation of the braking system.

By manually releasing the PB, operators can ensure that the vehicle can be moved or repositioned safely, preventing any potential hazards associated with a stuck or improperly engaged parking brake. This action is vital in emergency situations where the standard automated systems may be compromised due to the MR leak.

While checking air pressure levels, activating backup braking systems, and notifying passengers are important maintenance and safety checks related to overall operations, they do not specifically address the immediate action required in response to the detection of an MR leak. The primary goal in this scenario is to manage the parking brake to ensure safe mobility of the DM car.