Improve the coherence in the given paragraph
Modern retarders are computer controlled to apply a precise amount of pressure on the wheels. Cars rolling down a yard's hump are slowed to a safe speed for coupling with cars already standing on the yard's tracks.
Modern retarders are computer controlled to apply a precise amount of pressure on the wheels so that cars rolling down a yard's hump are slowed to a safe speed for coupling with cars already standing on the yard's tracks.