Starting/Charging Systems (H4SO): Generator: Inspection: Rotor

Inspect the slip rings for contamination or any roughness on the sliding surface. Repair the slip ring surface using a lathe or sand paper.

Measure the slip ring outer diameter. Replace the rotor assembly if the slip ring is worn.

Slip ring outer diameter: 

Standard 

22.7 mm (0.894 in) 

Limit 

22.1 mm (0.870 in) 

Using a circuit tester, check the resistance between slip rings.

If the resistance is not within the standard, replace the rotor assembly.

Specified resistance: 

Approximately 1.6 - 1.9 Ω 

Fig 1: Checking Resistance Between Slip Rings

Check the continuity between slip ring and rotor core or shaft. If the resistance is 1 Ω or less, replace the rotor assembly because the rotor coil is grounded.

Fig 2: Checking Continuity Between Slip Ring And Rotor Core

Check the rear ball bearings. If there is any noise, or the rotor does not rotate smoothly, replace the bearings.