TTX Series DC Actuator Installation & Maintenance Instructions |
31
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7.0 MAINTENANCE PROCEDURES
7.1 LUBRICATION
Tritex TTX Series actuators lubricated with grease require
periodic inspection and renewal of the bearing and roller screw
grease to maximize actuator life. Maintenance indicators during
a physical inspection include:
• Contamination of grease with foreign matter
• Leaking seals
• “Burnt” smell of the grease
• Grease is gritty in appearance
• Grease is dehydrated (dried out)
Although application-specific performance makes it difficult
to provide an exact number of hours of operation before
maintenance is required, the following factors will help
determine lubrication maintenance cycles.
Temperature
– Temperature is the most significant factor
affecting grease life. Exlar’s testing of Mobil SHC 220 synthetic
grease indicates ideal performance operation in ambient
temperature ranging from 32 °C to 55 °C (90 °F to 130 °F).
Within this temperature range, the grease has a long service
life. Operation In temperatures above this range decreases the
effective grease life. For every temperature rise of 15 °C (60 °F),
grease life is reduced by approximately 50%.
Speed
– The rotational speed of the actuator will generate heat
(thus raising the grease temperature) and potentially resulting in
lubricant being thrown off the roller screw.
Load
– Load contributes to the stress applied to the roller
screw mechanism and the pressure applied to the grease thus
impacting the overall lubricant life and relubrication interval.
Load directly impacts the amount of power put into the actuator
adding to the heat generated by roller screw speed. This heat is
transmitted to the lubricant eventually separating the oils from
the thickener and reducing grease life.
Orientation
– Gravity can cause grease migration over time,
especially in vertical applications at elevated temperatures.
The table below provides a general guideline for recommended
lubrication renewal cycles.
RMS
Rotational
Speed (RPM)
Recommended Grease Renewal Period (hours)
Case Temp.
65
°
C (149
°F)
Case Temp.
80
°
C (176
°F)
Case Temp.
95
°C (203 °F)
250
10,000
5,000
2,500
500
8,500
4,250
2,125
1000
6,000
3,000
1,500
1500+
3,500
1,750
875
Recommended lubrication renewal cycles
Grease renewal procedure
1. Remove the four bolts connecting the faceplate and any
mounting accessories from the front of the actuator.
2. Remove the roller screw by turning it counterclockwise and
threading it out of the cylinder. To remove the screw, it may
be necessary to hold the roller screw cylinder to keep it
from turning. Turning the shaft will help force the faceplate
assembly to break free of its housing.
3. Use a brush to work approximately 10 cm
3
(0.6 in
3
) of
grease into the roller screw assembly for every 100 mm
(3.9 in) of stroke length. Be sure all the threaded
surfaces of the screw assembly are covered. This can
be accomplished by applying grease to a few places on
the roller screw assembly and rotating the components
repeatedly in both directions to work the grease into the
assembly.
IMPORTANT
! Excess grease does not improve
lubrication and requires greater torque when the motor is
returned to operation.
4. With the actuator in the vertical position and the open end
of the roller screw cylinder facing up, position the roller
screw above the cylinder so that it is aligned axially with the
roller screw cylinder.
5. Slowly turn the roller screw clockwise in quarter to half
turn increments while maintaining contact with the interior
threaded cylinder (ITC). This helps align the threads on the
roller screw with the threads in the ITC. Do NOT force the
roller screw into the cylinder.
