Rail skates are usefull in flat switching and hump yards to prevent cars from rolling out to foul adjacent tracks.
Skates can also prevent flat spots on wheels caused by excessive application of hand brakes.
To apply, place the skate on the rail ahead of the rail car and allow the car to roll onto the skate. The weight of the car pressing down on the skate increases the friction between the wheel and rail to effectively slow the movement. Friction skates can also be placed on the rail ahead of bumping posts to reduce the damage caused by excessive speed impacts. Multiple skates can be used on tracks with down grades or where heavy loads are involved. To remove, simply back the rail car off the skates.