Single-acting or double-acting hydraulic actuator (gas cartridge or spring) for mounting on quarter-turn valves (butterfly valves or ball valves). Actuator flange to ISO 5211. Control pressure up to 160 bar. Mounts on valves with square or flat shaft end. Force transmission via rack-and-pinion or scotch-yoke kinematics provides output torques of up to 55,000 Nm which are ideal for actuating quarter-turn valves. Equipped with a visual position indicator and adjustable travel stops for open/closed position as standard. Optional manual override. Can be equipped with a hydraulic power unit: for shut-off, as a safety block, ESD block, as a bypass device enabling manual override. Can be combined with all limit switch boxes of the AMTROBOX/AMTROBOX R type series.