CAT Engine Course (Part 3)Air Induction System

Clean each crankcase breather element every 1000
service hours or oil change. Wash the breather
with clean solvent or clean diesel fuel.

Air Induction system



AIR INDUCTION AND EXHAUST SYSTEM
In this diagram of the air induction and exhaust system, we seethe turbochargers (two), the air inlet system piping, theaftercooler, the air inlet plenum and elbows, the inletport and intake valves, the combustion chamber, the exhaust valves and the exhaust manifolds.
The location of the air inlet system, exhaust manifolds, turbochargers, piping, aftercooler and air plenum are all in the center of the vee of the block.

Intake air comes through the air cleaners (not shown) and into the compressor inlet of each turbocharger.

Velocity of the air is increased by the turbocharger compressor impeller. The air is sent through the piping into the aftercooler inlet where it has increased in pressure and temperature.

The air then goes down through the aftercooler into the plenum chamber in the center of the vee. The air is cooled by jacket water in theaftercooler.

The decrease in temperature of the air can

range from 38º to 93ºC or 100º to 200ºF.



AIR INDUCTION AND EXHAUST SYSTEM
From the plenum chamber, the air goes throughpassages along the sides of the aftercooler, through aluminum elbows into the inlet ports, inlet valves and into the combustion chambers.
After the combustion or power stroke, the exhaust gases go out through the exhaust
valves, exhaust manifold, through theturbocharger turbine and goes out into the
outside air.

This arrangement of the 3512 Engine has two turbochargers and an aftercooler.

The location of the turbochargers and aftercooler on the vehicle arrangement is in the vee of the banks of cylinders.

The two turbochargers send air into the aftercooler air inlet.



The air inlet system, exhaust manifolds, turbochargers, piping, and aftercooler are all located in the center of the vee.
From left to right are the:
1. coolant manifold (left)
2. exhaust manifold (left)
3. aftercooler
4. rear lifting bail (eye)
5. exhaust manifold (right); and the
6. coolant manifold (right)



Watercooled manifolds and turbochargers are available on marine engines and are available as attachments on the industrial and generator sets.
On 3500 Engine Arrangements with water cooled exhaust manifolds, the coolant manifolds will be (combined with) the exhaust manifolds.


Here we see a generator set arrangement.

The air filter housing and turbochargers are on the rear of the engine. We can also see the:
1. emergency shutoff system
2. premium instrument panel; and the
3. air starting system with filters



This is the rear of the engine. On the industrial generator set engines, the turbochargers are mounted on the rear of the engine.



Here we see the electrical connections for the solenoid of the emergency air shutoff valve.

A sensor in the control panel activates the emergency shutoff system when the engine overspeeds (engine rpm goes higher than the maximum rpm setting).

Other sensors activate the fuel shutoff solenoid and STOP engine operation, when conditions of low oil pressure and high coolant temperature exist.
The remote shutoff also activates the fuel shutoff solenoid to STOP engine.

This is the air inlet reset control of the emergency airshutoff. This is one style. There is another style.

With the pointer in the vertical up position, it is set to RUN. When the solenoid is activated, thevalve goes down closing off the inlet air, and the pointer goes to the STOP position.

This must be RESET (set again) to RUN manually before the
engine is started again and after the problem has
been corrected.