Contents: 18.2.5.1. Carbon brushes and brush…⇓ 18.2.5.2. Rotor ⇓ 18.2.5.3. Starter ⇓ 18.2.5.4. Diodes ⇓
18.2.5.1. Carbon brushes and brush holder crossbar
Check the carbon brushes for good contact with the slip rings. Check the mobility of the carbon in the guides and, if necessary, clean the brush holder with Tri.
Figure 247. Carbon brushes are soldered in the indicated places.
Measure the length of the protruding part of the carbon brush. If the wear line is reached, the brushes must be replaced. To do this, the old brushes need to be removed and the new ones soldered on.
The brush wear line should protrude 2-3 mm from the end of the brush holder. Hold the brush in this position and solder the brush wire (core) with good zinc solder.
18.2.5.2. Rotor
If the contact rings are dirty or worn, wipe them with a cloth soaked in Tri. Any scratches can be polished with a fine lubricating paste.
To test the insulation, one tip of the ohmmeter is placed on the rotor core and the other on the slip ring. The ohmmeter reading should be continuous (figure 248). If this does not happen, the entire rotor must be replaced.
Figure 248. Checking the rotor for short circuit to the housing.
To check the rotor winding for current flow, both tips of the ohmmeter must be placed on the contact ring. If the reading is not within 2.0-6.0 ohms, the rotor needs to be replaced (figure 249).
Figure 249. Checking the rotor for current interruption
18.2.5.3. Starter
Short circuits occur in most cases due to strong heating of damaged areas and are detected during inspection. You can also place the tip of the ohmmeter on the end of the phase and the other tip on the stator housing. The device must give continuous readings (figure 250). Otherwise, the stator needs to be replaced. To test the stator for current interruption, you need to connect the three stator wires to each other one by one.
Figure 250. Stator short circuit test to housing.
If there is no reading, the current flow is interrupted (figure 251).
Figure 251. Stator current interruption monitoring
18.2.5.4. Diodes
Accurate testing of diodes for the presence of conduction voltage and the establishment of reverse current can only be carried out using a special test device.