Compressor - piston type, indirect two-cylinder, single-stage compression

Aluminum pistons with floating pins; against axial movement, the fingers in the piston bosses are fixed with retaining rings

Air from the engine air filter enters the compressor cylinders through self-acting reed inlet valves 21.

ZIL-131 compressor

The air compressed by the pistons is displaced into the pneumatic system through self-acting reed pressure valves 13 located in the cylinder head.

The block and head are cooled by liquid supplied from the engine cooling system.

The liquid in the compressor cooling system is supplied from the water jacket of the engine inlet pipeline and drained from the head into the suction cavity of the water pump.

It must be borne in mind that the filling of the compressor cooling system occurs only when the engine is running.

Therefore, after pouring liquid into the radiator, you need to start the engine, let it run for 3-5 minutes and then check the level in the radiator.

Turn off the air supply by the compressor to the pneumatic system as follows.

When the air pressure in the pneumatic system reaches 7.0-7.4 kg / cm², the pressure regulator supplies compressed air through channel "A" in the cylinder block under the plungers 26 of the unloader, which, rising, open the inlet valves 21 of two cylinders, thereby stopping the air supply to the pneumatic system, since the air is able to freely move from cylinder to cylinder.

When the air pressure in the pneumatic system drops to 5.6-6.0 kg / cm², the regulator stops the supply of compressed air under the unloader plungers.

Air from under the plunger goes out to the atmosphere; the plungers, under the action of the rocker spring, are lowered, releasing the inlet valves, and the compressor again begins to pump air into the pneumatic system.

Oil to the rubbing surfaces of the compressor is supplied through a tube from the engine oil line to the rear cover of the compressor crankcase, and through the seal through the channels of the crankshaft to the connecting rod bearings.

The main ball bearings, piston pins and cylinder walls are splash lubricated.

Iron pulley.

Compressor maintenance

Periodically, it is necessary to check the tightness of the nuts, the compressor mounting on the engine head, the pulley mounting, the tension of the drive belt, the tightness of the nuts of the studs that secure the head.

ZIL-131 compressor head tightening diagram

The nuts of the studs securing the head should be tightened evenly, in two steps, in the order indicated in fig. 2.

The final tightening torque should be within 1.2-1.7 kg / m after 80,000-100,000 km of run, combined with seasonal maintenance (spring), it is necessary to remove the compressor head to clean the pistons, valves, seats, springs , air channels, as well as to check the operation and tightness of the valves and plungers of the unloader.

Valves that do not provide tightness must be lapped to the seats, and badly worn or damaged ones should be replaced with new ones.

New valves should also be lapped into their seats until there is continuous ring contact when checking for paint.

It is necessary to check the condition of the sealing rings of the plungers 26 (Fig. 1) of the unloader and, if necessary, replace the rings.

In this case, the following order must be observed:

  • 1. Start the engine and bring the pressure in the pneumatic system to 7.0-7.4 kg / cm².
  • 2. Stop the engine.
  • 3. Remove the rubber hose connecting the engine air filter to the compressor.

If the unloader is not hermetic, a characteristic noise of the passed air will be heard in the air supply pipe to the compressor, and a slight pressure drop will be noted on the pressure gauge of the pneumatic system.

  • 4. Reduce the air pressure in the pneumatic system to 5.6-6.0 kg / cm², while the plungers will be lowered.
  • 5. Remove the air supply pipe, remove the spring and rocker,

Then, lift the stem socket and remove it together with the stem, after which, remove the plunger from its socket with a wire hook, inserting it into a hole with a diameter of 2.5 mm at the end of the plunger or supplying compressed air to the horizontal channel of the unloader of the cylinder block.

  • 6. Replace worn o-rings on plungers. Before installation, the plungers with o-rings should be lubricated with oil used for the engine.

Signs of a compressor malfunction are the appearance of noise and knocking in it, an increased amount of oil in the condensate drained from the airx cylinders.

Increased oil content in the condensate is usually the result of worn piston rings, oil seals at the rear end of the crankshaft, bearings of the lower heads of the connecting rods, or a clogged oil drain pipe from the compressor.

Adjusting the tension of the compressor drive belt

The compressor drive belt must be tensioned so that when a force of 4 kg is applied, the deflection of the belt branch located between the compressor and fan pulleys is 5-8 mm.

Belt tension should be checked daily.

The tension of the compressor drive belt is adjusted by moving the compressor.

To do this, loosen the nuts securing the bottom cover to the bracket and use the adjusting bolt 20 to provide the required tension.

Next, tighten the compressor mount and lock the adjusting bolt with a locknut.