The lock out device functions as a safeguard to protect mechanical service employees from unintended train movement while working on the train or on locomotive consists.

The small device is inserted into the reverser handle cavity and then locked into place with a padlock and a tag indicating the locomotive is "Locked Out".

The device provides a positive lockout on the locomotive by preventing the movement of the reverser or throttle.

An approved minimum standard for "ON Track Locomotive Lockout" used system wide on Canadian Pacific Railway.