An alternating current generator with a built-in semiconductor rectifier and an integrated voltage regulator is the main source of electricity

The generator is a three-phase twelve-pole synchronous electric machine with a built-in rectifier unit, an interference suppression capacitor, a brush holder with a voltage regulator and a continuous ventilation system.

Generator: 1 - brush holder; 2 - stator; 3 - rotor shaft; 4 - fan; 5, 7 - bearings; 6 - pulley; 8 - slip rings; 9 - brushes

The generator operates in a single-wire electrical circuit of the bus with a “minus” connection to the body.

The generator is connected in parallel with the batteries and provides power to consumers in any engine operating mode, as well as recharging the batteries.

The generator is installed on the engine and is driven by the engine crankshaft pulley.

The generator is attached to the engine with two legs through a bracket and with a third leg to the tension bar, when moving along which the generator drive belt is tensioned.

The schematic diagram of the generator is shown in Fig. 2

Generator circuit 3112.3771; 1 - voltage regulator; 2 - rotor; 3 - stator; 4 - rectifier block; 5 - noise suppression capacitor. Conclusions: “+” - for connection to the battery and load; "Ш" - for connection with the ignition switch and the battery charge indicator lamp; "W"—for connection with a tachometer; "+0” - for connection to the starter interlock circuit

Attention! Disconnect and connect wires to the generator only with the battery disconnected.

Proper operation of the generator is ensured only if there is a reliable electrical connection of all contacts, including between the generator housing and the engine.

Operating the generator with the battery disconnected can damage the voltage regulator, as well as other consumers of the on-board network.

Maintenance and repair of the generator should only be carried out in specialized workshops by qualified specialists.

Check the rectifier unit only on a disassembled generator with the stator winding disconnected.

Check only from a direct current source with a voltage of no more than 24 V, connected in series with the test lamp.

Generator maintenance

To ensure the operation of the generator, it is recommended to keep the generator clean and follow the following maintenance rules.

Check the functionality of the generator daily using the readings of the warning lamp and voltmeter located in the instrument cluster on the instrument panel.

When the engine starts, the warning lamp should light up, and after the engine starts, it should go out.

During normal operation of the generator, the voltmeter needle is in the green zone of the “G” scale (generator).

The location of the voltmeter needle in any of the red zones of this scale indicates a malfunction of the generator.

The condition and tension of the drive belts should be checked daily. During TO-1, the check is carried out using measuring instruments.

Particular attention to belt tension should be paid at the beginning of their operation for (1-2) days.

The belt tension is adjusted so that when you press the middle of the belt with a force of 40 N, the deflection is within (10-15) mm.

When installing new belts, it is allowed to set a lower deflection value - 10 mm.

Belt tension is adjusted using a tension bar.

To do this, after loosening the fastening of the generator to the bracket and bar, move the generator housing to the required position and secure it.

Attention! If the belt tension is weak, the generator will not deliver full power. If the belt is over-tensioned or misaligned, the generator will fail prematurely.

The criterion for the limiting state of a belt is delamination of more than 1/3 of the length, the presence of rubber cracks deep to the cord cord and the impossibility of compensating for elongation in the drive.

When checking the tension and installing a new belt, check for damage, oiliness of the surfaces of the pulley grooves and the location of the pulley grooves in the same plane.

At least once a month it is recommended to check the charge level of the batteries, which should be at least 75%.

During TO-2 without removing the generator from the engine, you should check the fastening of the generator to the engine and the fastening of the nuts of the coupling bolts of the covers.

Check the tightness and cleanliness of all connections of wires to the generator and batteries. If necessary, clean the connections, tighten the contact nuts and screws.

At each seasonal maintenance (without removing the generator), you should check the condition of the brush assembly in the following order:

Disconnect the wire from terminal "Ш" of the generator.

Unscrew the screws securing the brush holder and carefully remove it.

Check the free (without jamming or jerking) movement of the brushes in the brush holder guides.

Check the height of the brushes, which should be at least 8 mm. If necessary, replace the brushes.

Install the brush holder with brushes on the generator in reverse order.

The generator should be removed from the engine only to perform routine repairs and work related to wear of slip rings, replacement of bearings and other special work.

If the wear of the contact rings exceeds 0.5 mm in diameter, then the rings must be ground.

Power supply and start-up diagram
Instrumentation diagram


The starter is a four-pole electric motor with an electromagnetic traction relay and a drive with a freewheel.

The starter is turned on using the instrument and starter switch key.

Attention! It is prohibited to turn on the starter while the engine is running, and also to move the bus by turning the transmission through the engine with the starter.

Checking the condition of the diesel starter

Every 120,000 km:

Check the tightness of the mounting bolts, tighten them if necessary.

Strip the wire ends to the starter and battery terminals and tighten their fastenings.

Remove the cover from the commutator side and check the condition of the brush-commutator assembly.

The working surface of the collector must be smooth and not have significant scorching.

If the collector is dirty or has signs of significant scorch, wipe it with a clean cloth soaked in gasoline.

If it is impossible to remove dirt or scorch by wiping, clean the collector with fine sandpaper.

If there is significant burn on the commutator that cannot be cleaned, grind the commutator on a machine.

The brushes must move freely in the brush holders and fit tightly to the commutator.

If the brushes are extremely worn, as well as if there are significant chips, replace them with new ones.

Blow out the brush-collector assembly and the cover on the commutator side with compressed air.

Check the condition of the starter relay contact system.

If there is significant burn, clean the contact bolts and the contact plate with sandpaper or a file, removing unevenness caused by the burn, without disturbing the flatness of the contact surfaces of the copper bolts.

If the plate and bolts are significantly worn, turn the contact plate over and turn the contact bolts 180°.

Check that the drive moves easily along the armature shaft. When the relay is turned on and off, the drive should move along the splines of the armature shaft without jamming.

Remove from the internal surfaces of the drive guide bushing (splined and smooth) and the adjacent parts of the shaft any contaminated thickened lubricant with wear products that has entered from the crankcase, which significantly complicates the axial movement of the drive along the shaft splines when the gear is engaged with the flywheel ring gear.

Apply a thin layer of lubricant CIATIM-221 (CIATIM-201) to cleaned surfaces.

Check the condition of the drive gear and thrust washers visually.

Position of the drive gear in the off position (A no more than 34 mm)
Measuring the gap from the end of the gear to the thrust ring

The gap between the end of the gear and the thrust washers in the on position should be (2-4) mm.

Possible malfunctions of the generator and starter and methods of elimination

Generator malfunctions

Fault in the wiring or contact connections to the generator or other batteries - Determine the location of the fault and eliminate the fault

No reliable contact between brushes and rings:

  • - the brushes are stuck in the guides - check the condition of the brush assembly and fix the problem;
  • - brushes are worn out - replace brushes;
  • - the rings are dirty or oily - wipe the rings with a clean cloth soaked in gasoline.
  • If dirt cannot be removed by this method, clean the rings with glass-coated sandpaper and wipe again

Desoldering of the excitation winding leads from the slip rings or a break in the excitation coil - Remove the brush holder with the voltage regulator.

Check the resistance of the excitation coil between the slip rings. When desoldering, solder, if broken, replace the rotor.

Failure (breakdown or break) of the diodes of the rectifier unit - Check and, if necessary, replace the rectifier unit

Fault (breakdown or break) of additional diodes of the rectifier unit - Check and, if necessary, replace the rectifier unit

Open or short circuit in the stator winding - Disassemble the generator, remove the stator and check the resistance of the phase windings.

With a working stator, the resistance of the phase windings should not differ from each other by more than 10%.

If there is a break or short circuit, replace the stator.

Breakage or short circuit of the rectifier block valves - Replace the rectifier block

The generator does not provide charging current

(The control lamp is on. The voltmeter needle is in the left red zone of the “G” scale)

Faulty generator excitation circuit unloading relay - Replace the relay

The charge control lamp flashes, the ammeter needle fluctuates

Loose drive belt - Tighten the belt

No reliable contact between brushes and rings: - See above

The voltmeter needle is in the right red zone of the “G” scale

The voltage regulator is faulty - Replace the voltage regulator

Short circuit in the generator brush assembly or in the circuit between the generator and the regulator - Eliminate the short circuit

The battery is faulty - Check, charge or replace the battery if necessary

Excessive tension or misalignment of the drive belt - Adjust the belt tension and eliminate the misalignment

Mechanical faults

Bearing noise

Bearings worn or damaged - Replace bearings

Starter malfunctions

The starter does not work (when it is turned on, the headlights do not dim)

  • - Broken or faulty wiring - Check the wiring to the starter and eliminate the fault. Wipe the collector with a cloth soaked in gasoline, or clean the collector with glass sandpaper. Check that the brushes are not stuck in the brush holders.
  • - Lack of contact between brushes and commutator
  • - Broken connections inside the starter

Clean the side edges of the brushes or replace worn brushes with new ones.

Check the condition of the brush springs and, if they are faulty, replace them.

Remove the starter, check and eliminate defects or replace the starter

- Traction relay malfunction

Clean the contacts of the starter relay or turn the contact bolts in the sockets 180° and install the contact plate with the reverse side, or replace the relay

The starter does not turn the engine or turns it very slowly

  • - Low engine temperature (winter) - Warm up the engine
  • - Using an inappropriate oil for the season - Change the oil
  • - Corrosion of contact connections on batteries - Clean contact connections
  • - Batteries are low or faulty - Charge or replace batteries
  • - Poor contact in the starter power circuit - Clean and tighten the wire terminals
  • - Burnt relay contacts - Clean relay contacts
  • - Poor contact of the brushes with the commutator - Clean the commutator and brushes, eliminate the hang-up, or replace the brushes
  • - Weak contact in the battery terminals - Clean, secure, lubricate

The starter armature rotates at high speed, but does not turn the engine

  • - The drive is faulty - Replace the drive
  • - Starter adjustment is broken - Adjust starter

The relay works intermittently (turns on the starter and then turns it off)

  • - Broken relay holding winding - Replace the relay
  • - Batteries are low - Charge or replace batteries

The drive gear does not systematically engage with the flywheel ring during normal relay operation

  • - The ends of the flywheel ring teeth are heavily clogged - Replace the flywheel ring
  • - Starter adjustment is broken - See above
  • - Seizing of the gear on the shaft due to lack of or poor-quality lubrication - Clean the shaft and splines from dirt and lubricate with CIATIM-221 (-201) lubricant
  • - Milling of drive gear teeth due to turning it on while the engine is running - Replace the drive

After starting the diesel engine, the starter remains in the on state

- The contact plate is welded to the bolts of the starter contact relay - Clean the contacts of the starter relay or turn the contact bolts in the sockets 180°, and install the contact plate with the reverse side. Or replace the relay