20-02245 REV E
11
MOTOR REMOVAL AND REPLACEMENT
The motors used in the RS-485 controller positioners are brushless stepper motors and
are noted for very long lifetimes without maintenance. Before undertaking motor
replacement, make sure that proper operating voltage is being provided by the
controller and interconnecting cable. In the event that replacement of the motor is
necessary, replacement of the motor as well as the associated control module PCA as
an assembly is recommended.
1.
Remove the end cap as previously described in
END CAP REMOVAL
and if oil-filled, drain the remaining compensating fluid.
2.
Remove the zip ties and disconnect the JST connectors.
3.
Remove the retaining ring, which secures the bearing plate.
4.
Mark the output shaft with the housing for re-assembly. Grasp the output
shaft and gently pull assembly from housing.
5.
The motor plate, which attaches to the motor and the fixed harmonic gear,
is now visible. Remove the retaining ring in the housing bore, which
secures the motor plate assembly. Be careful not to scratch the inside of
the housing with the ends of the rings, particularly in the vicinity of the O-
ring sealing surfaces. Keep these rings separate from the outer rings,
which retain the end cap. The outer rings are made of stainless steel for
corrosion protection. If one of the retaining rings is “wavy”, note that it
belongs closest to the motor.
The motor assembly is removed, in most cases, by inverting the housing and tapping it
with a non-metallic hammer or other object. If this technique is used, be careful to
protect the gear and motor assembly as it slides out of the housing.
6.
When the motor assembly is removed, be careful that the locking pin is
not lost. This normally remains attached to the inside wall of the housing.
If defective, the entire motor assembly including the motor plate and the attached gears
should be returned to ROS for repair or replacement. If return is not possible, the
motor, motor plate, and harmonic gear components must be disassembled to replace
the motor.
IMPORTANT:
Note the orientation of the flex spline of the harmonic gear assembly
relative to the motor shaft before removing. During re-assembly, it must be mounted in
the same position for proper operation and torque output of the gear mechanism.
7.
NOTE:
The position of the wave generator with respect to the motor
shaft. Remove the retaining ring, which holds the wave generator to the
motor shaft and remove this portion of the gear mechanism.
