Mitsubishi Electric MELFA RH-12SQH Series, Instruction Manual, Page: 73 / 106

5Maintenance and Inspection
Maintenance and inspection procedures 5-64
■ Replacing the J3 axis timing belt
1) Fig. 5-4 shows the methods for inspecting, adjusting and replacing the timing belt.
2) Move the robot posture with the teaching pendant so that the J3 axis contacts the mechanical stopper of
upside. The J3 axis brakes must be released.
3) Turn off the controller power.
4) Be careful not to let the timing pulley (4) on the J3 axis motor move while the belt is being changed.
5) If the pulley (4) and (5) position relation deviates, the position could deviate.
6) Loosen the J3 motor installation screws (1) to lift the J3 motor (3) upward and remove the timing belt (2)
from the timing pulley (4).
7) Loosen the shaft installation screws (6) to lift the shaft upward and remove the timing belt (2) by lifting it
from the bottom spline section. (Refer to Fig. 5-4 .)
8) Install a new timing belt on the timing pulleys (4) and (5) in the reverse order of the procedure described in
steps 6) and 7) above.
9) With the J3 axis touching the upper mechanical stopper, hook the timing belt (2) around the timing pulleys
(4) and (5).
10) Perform tension adjustment referring to steps 3) to 6) in " ■ Adjusting the J3 axis timing belt" and
"(4)Timing belt tension" on page 67 .
For more accurate tension adjustment, pull out the idler (4) with a force of 65N for RH-6SQH or 90N for
RH-12SQH/18SQH using the push-pull gauge, and then tighten the idler installation screws (3) as shown in
Fig. 5-5 . The use of the method as shown in Fig. 5-5 is recommended.
11) The position could deviate after the belt is replaced. Confirm that the position has not deviated.
Fig.5-5 ： J3 axis timing belt tension
(8)Push-pull gauge
Remove the bracket attached
vertically on the shaft fastening area.
(1)J3 motor inatallation screw