The RB Series of linear profile guide rail brakes from Nexen Group (Vadnais Heights, MN) use spring force to secure the load in holding applications. Each brake clamps directly onto the center of the guide rail for positive braking and holding in all axes. The brakes eliminate drive train backlash and elasticity, and are spring-engaged and air-released for power-off. Other features include an adjustable facing gap, a large friction facing contact area, and field-serviceable friction facing replacement.