C4  Maintenance  6. Joint #2 
 
C Series Maintenance Manual Rev.2  79 
6.2  Joint #2- Replacing the Reduction Gear Unit 
A reduction gear unit consists of the following three parts.    Also, two additional parts are included as 
accessories. When replacing the reduction gear unit, be sure to replace these parts all together as a set. 
Reduction gear unit: Wave generator, Flexspline (CRB combined), Circular spline 
Accessory: O-ring×2 
For details, refer to C4 Maintenance: 17. C4 Maintenance Parts List. 
It is recommended replacing the O-ring (for Joint #2) when replacing the reduction gear unit. 
Maintenance 
Joint #2 reduction gear unit 
Tools 
Hexagonal 
wrench 
width across flats: 2.5 mm  1 
For M3 hexagon socket head cap bolt 
For M5 hexagon socket set screw 
For M4 hexagon socket head cap bolt