A broad range of hydraulic actuators with a choice of rack and pinion, scotch yoke, helical slot and linear designs suitable for heavy-duty service in the harshest environmental and operating conditions. Rack and pinion actuators provide the most economical on-off and modulating control for small to medium quarter-turn valves. The scotch yoke design creates high break-out torques making them suitable for quarter-turn valves up to the largest sizes. Helical slot is used when a reduced foot print impact is requested (it is available with a four-different output curves equivalent to R&P or SY), including models for very high-pressure applications.