Epson C12 Series Manipulator Manual page 242

Maintenance 8. Joint #4
Drive boss and the motor shaft:
Hexagon socket set screws: 2-M4×4
Tightening torque: 2.5 ± 0.2 N·m
Align the screws to the two flat faces of the motor shaft and fix them.
Drive boss and the pulley 1:
Hexagon socket set screws: 2-M4×4 (with a brass bushing)
Tightening torque: 2.5 ± 0.2 N·m
Fix the set screws while pressing the pulley 1 to the drive boss.
The brass bushing is not necessary for the screw for the flat surface (D-cut). Set the bushing to the other
screw and then fix the screw.
4. Put the Joint #4 motor unit inside the Arm #4.
5. Pass the timing belt around the pulley 1 and pulley 2 and
temporarily fix it.
Hexagon socket head cap bolts: 2-M4×15 (with a washer)
Check that the teeth of the timing belt engage with these of the
pulley.
As a rough guide of temporary fixing, check that the motor unit can
be moved by hand, and it does not tilt when being pulled. If the
belt is too loose or too tight, it will not have proper tension.
6. Apply tension to the Joint #4 timing belt and fix the Joint #4 motor
unit.
Joint #4 timing belt tension: 15 to30 N
Belt tension meter setting value
Weight: 2.5 g/mm width × m span, Width: 6 mm, Span: 61 mm
Hexagon socket head cap bolt: 2-M4×15 (with a plain washer)
Tightening torque: 4.0 ± 0.2 N·m
Regarding belt tension:
NOTE - Jumping (position gap) may occur if the value is below the lower limit.

- Vibration (abnormal noise) or reduction in life of the parts may occur if the value exceeds the upper
limit.
- When you replace with a new belt, belt extends and the belt tension may decrease in the initial stage.
Make sure to operate the robot two to three days and check the belt tension again.
228 C12 Rev.3