Most rides use relatively simple mechanical means for locking lap bars and shoulder bars in place. Some rides use a combination of mechanical and hydraulic systems, and the most recent systems generally use hydraulic locking systems.

Roller coaster restraints are engineered with redundant mechanical and electrical safety systems to ensure they remain locked even in the event of a total power failure. Most modern rides use a "ratchet" or a "hydraulic" locking system. In a ratchet system, a heavy-duty metal bar moves over a series of notches (the clicking sound you hear); once the bar moves down, a "locking pawl" prevents it from moving back up until it is released by a mechanical lever in the station. Newer coasters often use hydraulic cylinders, which allow for a more custom, infinitely adjustable fit rather than fixed notches. These are held in place by valves that require an electrical signal or physical pressure from the station's track-side equipment to open. Furthermore, most systems are "fail-closed," meaning that without an active release command, the default state of the restraint is to stay firmly locked, providing peace of mind even during high-G maneuvers or inversions.