Anti-climbers
To protect the crew and passengers, most modern locomotives and passenger cars are fitted with a device known as an anti-climber above the coupler to prevent colliding objects from travelling up over the frame and through the locomotive cab area or through the passenger car. Where a pilot is not fitted, a different type of anti-climber may be used. This is to prevent one passenger car from riding up over another, or telescoping in a collision.
Read more about this topic: Pilot (locomotive)