a correlator system for automatic car wash has roller assemblies for supporting the front left and right wheels of a vehicle entering a car wash line . a set of guide rails or bars cooperate with the roller assemblies to adjust axial displacement and angular misalignment between the vehicle &# 39 ; s front end and a conveyor track transporting the vehicle through the car wash facility . the rollers in the roller assembly rotate freely with minimal friction , axially displacing the front end of the vehicle and adjusting the angular misalignment of the front wheels . the low friction , easy - to - rotate rollers are provided with a plurality of braking elements that generate friction against the rollers , retarding their rotation when a worker steps thereon . the friction generated by the braking elements is insufficient to prevent roller rotation during alignment of the front end with the conveyor track . injuries to car wash personnel caused by loss of balance when stepping on the rollers are virtually eliminated , and an accurate alignment of the vehicle &# 39 ; s front end with the car wash conveyor track is reliably achieved .