Opposite chambers in the actuator are connected by pressure equalizing passages in the upper and lower heads. In this manner, the actuator produces perfectly balanced torque as hydraulic force simultaneously pushes both of the rotor vanes away from the stationary shoes.
Torque output of the rotary vane actuator remains constant throughout the full rotation of the valve. Constant torque output is an especially important feature in high flow applications, plug valve applications, and for valves which have rotating seats. Constant torque output ensures that your specified safety factor will not diminish at various positions during the valve stroke.