The disclosure provides a blowout preventer (BOP) system with an actuator for opening and closing a ram. The actuator includes a locking system having a clutch piston to operate a clutch having ratcheting teeth. The locking system disengages the clutch prior to the ram opening and closing. The clutch piston has a first portion with a larger area than a second portion. A clutch fluid pressure acts on the first portion, and a closing fluid pressure acts on the second portion. This area difference in the clutch piston portions allows the clutch to be disengaged during closing operations, even when the closing fluid pressure is the same as the clutch fluid pressure and the clutch is biased engaged by a bias assembly. Further, closing fluid pressure is applied to lessen the load on the clutch ratcheting teeth, while the clutch fluid pressure is applied to unlock the clutch.