Actuator Operating Principle
In the gearbox stage, the rotational speed of the motor is transmitted to the output rod via two sets of gears.The primary reduction is achieved by a planetary gear, while the secondary reduction is realized by a worm gear, which is held in its central position by a set of tension springs.
In the event of an overload - i.e., when the torque applied to the output rod exceeds the preset spring torque - the central worm gear will move axially, triggering fine adjustment of the switch and signalling device to provide system overload protection.
The output rod is connected to the worm gear during motor operation, and to the handwheel during manual operation, via a coupling controlled by an external shift lever. When the motor is not running, the motor drive can be easily disconnected, and the handwheel can be engaged simply by operating the lever.
As motor drive takes priority over manual operation, the system automatically reverts to motor drive when the motor restarts. This prevents accidental handwheel rotation while the motor is running, further protecting the system.
Since the handwheel is directly coupled to the output rod, normal manual valve operation is ensured even in the event of internal gear failure or damage.
The switch and signalling device mounted on the gearbox features a sealed enclosure that protects its internal components and supports the following functions:
1. Local or remote indication of valve position
2. Actuator/valve overload protection
3. Valve travel limit control
4. Electrical interface connection
The actuator can be mounted on various types of valves via the output rod, which is compatible with a wide range of standard valve stem configurations.
