C8 Maintenance    8. Joint #4 
 
C Series Maintenance Manual Rev.2  345 
8.1  Joint #4 - Replacing the Motor 
  Name  Qty.  Note 
Maintenance 
Parts 
AC servo motor 100 W  1 
2172051   
(common to Joints #4, #5, #6) 
Tools 
Hexagonal 
wrench 
For M4 hexagon socket set screws 
width across flats: 2.5 mm 
For M3 hexagon socket head cap bolts 
For M4 hexagon socket head cap bolts 
Cross-point screwdriver (#2) 
For cross recessed head screws 
For pulley position adjustment 
Belt tension meter  1  Refer: Unitta U-505 
* The belt tensile jig is an assembly jig.    Use the jig when adjusting belt tension. 
The brake is mounted on each joint to prevent the arm from lowering due to its own weight while the 
Controller power is OFF or the motor is OFF status.    The brake does not work during replacement. 
Be careful when performing maintenance work. 
The motors are common for Joints #4, #5, and #6. 
The Joints #5 and #6 motors have an identification label for preventing misconnection of the connectors.   
The label is not necessary for the Joint #4 motor.    (There is no connector identification label for the 
Joint #4.)