Disassembly/AssemblyGuidelinesIRB 6400Page 4 - 7MaintenanceOil Change Gearbox, Axis 4 (U61 )• Move the upper arm to the horizontal position .• Remove the plugs (A) and (B).• Drain off the old oil through the hole (A). See figure below .• Clean the magnetic drain plug before refitting .• Refit the drain plug (A).• Fill up with new oil until the oil level reaches the lower edge of the fillinghole (B).For S/2.9 - 120 robots only:• Move the upper arm to the maximum upper position before draining the oil .• Move the upper arm to the vertical position before filling oil.• Fill up with new oil until the level is 30-35 mm below the upper side of thecover.Volume approx.:6 litres (1.75 US gallon).Correct oil level for axis 4 is to the lower edge of the upper oil-level plug (B) .AB