Procedure for the general rewiew of the rotork servomotor

PROCEDURE FOR THE
GENERAL REVISION
OF THE
ROTORK
SERVOMOTOR
GHARBI BESSEM MAINTENANCE PLANNER& INSTRUMENTATION
COORDINATORMAINTENANCE

PURPOSE OF THE WORK
• The purpose of this work is to show the
operating mode of a revision of a ROTORK
servomotor
• Improve technical knowledge for the control
of ROTORK servomotors
• Establish a procedure of intervention on the
mechanical, electrical and control equipement

PRESENTATION
• The review took as an example the model (IQ90
A30A) CENTER COLUMN AND BASE
• The work involves the dismantling of all
mechanical parts for inspection and change
wear parts (bearing, seal) , check electrical and
electronic parts
• identification of card and connection
• Make the test of handling under electrical
tension.

DEFINITION
• A servomotor is a motorized system capable
of reaching predetermined the valve positions
and then maintaining them.
• The position is in the case of a rotary motor an
angle value and in the case of a linear motor a
distance.
• Electric motors as well as hydraulic motors are
used.

OPERATION OF THE
SERVOMOTEUR
*After receiving an operating command, the servomotor
drives the valve towards OPEN or CLOSED.
*Two types of fundamentally different stops are possible:
The first one: called end stop, is only dependent on the
position. The control switches off the servomotor from the
cutoff point reached.
The second one: requires the shutter to operate at a
defined force or torque to seal the valve on its seat. This
break is called stop on torque limiter. The control is
programmed to shut off the servomotor when the torque
threshold has been exceeded. Limit sensor have to signal
the position of the valve. GHARBI BESSEM MAINTENANCE PLANNER& INSTRUMENTATION

OPERATION MODE
• A set value and a real value are indicated on the main board. The motor is
driven until the actual value is equal to the setpoint. Generally, the control
system requires a copy of position
Position to
reach
Exit
position
Current position
This is 0% or 100%
or an intermediate
position
This is 0% or 100%
or an intermediate
position
Main card

WORKPLAN
• The work consists of a mechanical + electrical
revision
• Identification of mechanical components
• identification of electrical components
• Identification of electronic components
Technical documentation

THE ROTORK SERVOMOTOR
ASSEMBLY CENTER COLUMN AND
BASE IQ 90
• 1: housing Subset
• 2: steering wheel Subassembly
• 3: electric motor Subassembly
• 4: terminal block Subassembly
• 5: Electronic Equipment Cover Subset
• 6: Electronic equipment

GENERAL PLAN
Sous ensemble carter
• Photo of the general plan
Under flying assembly
Under cover cover of electrical
equipment + e-cards
Electric motor Subassembly bulkhead
terminal

REVISION UNDER SET # 1 CARTER
• DIFFERENT STEPS
• Servomotor oil change
• State and oil quality inspection
• Disassembly of the spring + seal
• Disassembly of the clutch fork
• Disassembly of the clutch ring
• Disassembly of the drive sleeve and the stop
• Disassembling the tangent wheel
• Disassembling the drive shaft of the magnetic counter
• Disassembly of the central axis and base Central bearings change
• Changes to all seals + Para oils

SERVO OIL DRAIN
• position the actuator on its base then open
the drain plug to empty the oil sump.
Oil drain plug

• A general inspection shows that the oil is not of good
quality There is no wear or damage part
INSPECTION OF GENERAL STATUS AND OIL
QUALITY

DISASSEMBLING THE SPRING + JOINT
HOLD
• locate the center column retainer o-ring press
the steel washer located below and roll the o-
ring up
O-ring
steel washer
Clutch spring
note:
take great care when releasing
the spring GHARBI BESSEM MAINTENANCE PLANNER& INSTRUMENTATION

PREPARATION FOR DISASSEMBLING
THE CLUTCH FORK

DISASSEMBLING THE CLUTCH FORK
• Lock the spring clamp to a horizontal position
and lift the fork at the same time by loosening
these 4 screws
NB:
Do not loosen the
adjusting screw
étrier
Fourchette

DISASSEMBLING THE CLUTCH RING
• remove the ring up.

DISASSEMBLING THE DRIVE SLEEVE
AND STOP
• Disassemble the bottom part of the base first

• Unscrew first the sleeve, the stop ring of the
stop and then remove it
muff
Stop ring

FIXING THE VALVE
The connection to the valve is made by two
elements. The first element called the servomotor
base that is securely screwed to the mounting
flange of the valve. (The size of this flange
increases with the value of the torque to be
transmitted).
The second element is the coupling, used to
transmit the torque or thrust of the servomotor to
the valve shaft. (Due to the large number of types
of valve construction, there are also a multitude
of types of couplings).

DISASSEMBLING THE TOOTHED
WHEEL
• Using a mallet tap on the central axis until
disassembly of the gear.

Reducer (HEXED WHEEL) The gear units used
are regularly wheel and worm gear units. The
reduction is often important. The operating
speeds of the valves are relatively low.
This type of transmission has irreversibility
characteristic makes it particularly suitable for
servomotors.
This type of gearbox makes it possible to
maintain the torque without powering the
motor, and, on the multi-turn servomotors, to
support the load due to the weight of the deck
or the potential of a pressure.

PREPARATION FOR DISASSEMBLING
THE CENTER AXIS
Tangent wheel
Central axis

•After disassembly of the central axis it is necessary to
change the central bearings
bearings
CHANGE OF CENTRAL BEARINGS

DISASSEMBLING THE MAGNETIC
COUNTER TRAINING AXIS
• Using a small screwdriver, remove the spring clip
holding the magnet to the axis then remove the axis
of the magnetic counter + disassembly of the
electronic card.
magnet
spring
clip
Axis of the magnetic
counter
Training gear

SENSORY RACE AND COUPLE
TECHNOLOGY
The limit switches are used to measure the
distance traveled and to signal when the end
position is reached. A torque limiter records
the force on the valve. Exceeding a limit value
is also reported. Servomotors frequently have
an absolute position encoder (digital or
analog).

• Torque measurement is not only used to signal
stopping at the end position. It is also used to
detect an anomaly during the maneuver, such
as that due to the presence of an object
trapped for example. This limitation makes it
possible to avoid a mechanical breakage. The
control is able to distinguish the normal stop
from the exceptional stop in intermediate
position by the state of the limit switch

EXPLODED VIEW OF PARTS REMOVED
FROM SUBASSEMBLY N ° 1
butée
Axe central
Clutch fork
the drive shaft of the
magnetic counter
Stop ring
Roue dentée
Bottom part of the base
Worm gear + rotor
Subset N ° 2:
steering wheelCover of the
electronic part
Clutch ring
Spring +
washer
GHARBI BESSEM MAINTENANCE PLANNER&
INSTRUMENTATION COORDINATOR MAINTENANCE

REVISION UNDER SET ° 2 WHEEL
• DIFFERENT STEPS
• Dismantling the steering wheel assembly,
gearbox and crankcase motion transmitter
• Separate the 3 subsets: steering wheel, gearbox
and motion transmitter
• Dismantling the parts of each subassembly
• Changing the seal + the ring oil

Disassembly of the steering wheel,
gearbox and motion transmitter
assembly
• use the 6 fixing screws with a 6mm Allen key
to separate the housing assembly, the
assembly should be lifted straight up.
reducer
volant
Mvt Transmitter

MANUAL CONTROL (FLYWHEEL)
Most electric actuators are equipped with a
handwheel for manual operation during
commissioning or during a power failure, for
example. The steering wheel does not turn
during engine operation thanks to the clutch

Separate the 3 subassemblies:
reducer flywheel and mvt transmitter
• Unscrew the 7 fixing screws with a 4mm Allen
key to disengage the 2 - part gearbox.

Exploded view of Parts removed from
subassembly N ° 2

ENGINE all types of electric motors are used. DC or AC motor, single phase or
three phase. However, preference is given to AC three-phase asynchronous
motors as well as the single-phase AC motor. Their robustness and their high
starting torque are two qualities appreciated in this area, especially when it is
necessary to release a valve locked in its seat.
Electric servomotors are used in extreme ambient conditions. Fan motors do
not fulfill the protection type requirements and are not used much. In fact,
the engines require a cooling phase after service. Servomotors are not
designed for continuous operation. This corresponds perfectly to the
application because the valves are not always maneuvered.
REVISION UNDER SET ° 3 ELECTRIC
MOTOR

REVISION UNDER SET ° 3 ELECTRIC
MOTOR
✓Disassembly of the stator
✓Disassembly of the rotor

Disassembly of the stato
• Disassemble the stator of the electric motor
by loosening the 4 fixing bolts with a 6mm
Allen key

Disassembly of the rotor
• Disassemble the rotor of the electric motor by
loosening the 4 fixing bolts and pulling it outwards

• Change of the following parts on the rotor

PLAN ÉLECTRIQUE

REVISION UNDER SET ° 4 CLOISON
TERMINAL
• DIFFERENT STEPS Disassembly of the cover of
the electronic part and the cover of the
terminal block Wire Identification and
Disassembly of the Bounded Partition Make
sure the connections are good

Role of the Electrical Connection The motor
supply cables and the signal cables are
connected to the electrical terminal block of the
servomotor to transmit control commands to it,
and to retransmit the position of the
servomotor to the control system. Ideally the
electrical connection must be made by a single
connector to prevent any decoupling during
maintenance.

Wire Identification and Disassembly
of the Terminal Block
• Remove the fixing circlip from the partition
and pull it out slightly. Cut the cable ties to
make it easier to locate and count the wires.
Disassemble the terminal block

UNDER SET 5: COVER OF ELECTRONIC
EQUIPMENT
• Disassembly of the protective cover Checking
the status of the communication card Battery
change

Disassembly of the cover of the
electronic part and the cover of the
terminal block
• Remove the cover of the electronic equipment
after having unscrewed the 4 fastening screws
using a 6mm Allen key and then that of the
partition.

OVERVIEW 6: ELECTRONIC
EQUIPMENT
Carte puissance
Main card
Carte
control
local
al
Carte
sensor
batterie
Carte relais

SERVOMOTOR CONTROL role of the main board
• The servomotor control ensures, on the one
hand, the servomotor signal processing and, on
the other hand, the processing of the operating
commands of the control system. This task can be
performed by an external command, for example,
a DCS. Modern servomotors are equipped with a
built-in control for on-site signal processing
without delay. The electrical control of the
motors can be realized by contactors or by static
electronic components

VUE GÉNÉRAL

CARTE DE COMMUNICATION

CARTE PUISSANCE

CARTE RELAIS

CARTE CONTROL LOCAL

BATTERY

CARTE LIMITE SENSOR

REASSEMBLY
The reassembly is done in reverse order of the mechanical
disassembly Added 5 liter of oil {SHELL SPIRAX gear oil 80w90)

Procedure for the general rewiew of the rotork servomotor

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