Section 2: Functional Description Of The Rts Fq Fail-Safe Quarter-Turn Actuator - Emerson Bettis RTS FQ Series Operating Manual

User Instructions
MAN-02-04-60-0351-EN Rev. 3
Section 2: Functional Description of the
In normal operation, the actuator is operated by a PM motor (1) via a worm gear stage (2)
and a planetary gear train (3). The motor drives the spindle nut of a ball screw (4). The sun
gear shaft of the planetary gear train is fixed in place by an operating current brake (5).
The ball screw converts the rotational movement of the gear unit into linear motion, which,
on the other hand, charges the spring assembly (7), which acts as an energy storage device.
On the other hand, a rack and pinion gear (6) converts the linear motion into the 90
output motion to move the fitting shaft (9).
There are no engaging or disengaging elements between the motor. The energy storage device
and the fitting shaft in the actuator. All the gear unit components are permanently engaged.
While moving against the fail-safe direction, the electric motor has to move both the fitting
and the energy storage device (disk spring assembly) for the fail-safe stroke.
If the supply for the operating current brake is interrupted by a power failure, or intentionally
triggers a fail-safe stroke, the actuator will no longer hold position, and the energy stored in
the disk spring assembly will be converted into kinetic energy so as to move the actuator and
thus the fitting to the fail-safe position. In this situation, the entire gear chain for the actuator
with the exception of the worm gear stage will be moved until the adjustable mechanical end
stop (8) is reached or, if applicable, be stopped for the fitting.
Owing to this operating principle, neither an initializing stroke nor resetting of the drive
is required after a fail-safe stroke. As soon as the power supply is restored, the actuator is
immediately ready for operation.
Figure 2
Functional Description of the RTS FQ Fail-Safe Quarter-Turn Actuator

Section 2: Functional Description of the RTS FQ Fail-Safe Quarter-Turn Actuator

RTS FQ Fail-Safe Quarter-Turn
Actuator
Cut-out of the RTS FQ Fail-Safe Quarter-Turn Actuator
Febraury 2019
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