STB Tension Brakes (29)STB 600 and 940 Brakes allow superior torque control for your web. Three different sized piston sets can be actuated singly or in any combination for a large number of torque-to-air pressure ranges. The ventilated rotor creates an airflow path that draws cooler ambient air into the center of the rotor. The flow path directs air past the interface and dissipates heat radially away from the unit.