This paper presents the development of an automatic control of retardant system and parking of wagons, where after unloading in the car dumper, passing through retarders and switches and crossings. The retarder system is a device installed on the rails, at the end of the ramp and is responsible for braking the wagons. Automatic control of braking and objectively determine the optimal speed to ensure that the engagement is smooth to the other wagons. Without this control, or if it fails, there may be a short stop before reaching the destination, or cause strong impact on engagement because of high speed, leading to possible breakdowns in couplers and wagons.