What must you check post movement of the locomotive at 1 to 3 MPH?

The appropriate action to take after the movement of the locomotive at speeds of 1 to 3 MPH is to check the brake application. This is crucial because ensuring that the brakes are properly applied and functioning is vital for the safety of the locomotive and the ability to control it in various operational scenarios.

After moving, verifying brake application confirms that the locomotive will stop as expected when necessary, preventing accidents or unintended movement. This step is integral to maintaining operational safety and adhering to standard procedures during the locomotive's operation.

Other checks, such as throttle position, hand brake status, or pressure readings, may also be important at different times during locomotive operation, but verifying brake application directly impacts immediate safety following a movement.