318C EXCAVATOR BTG

318C EXCAVATOR BTG

Service Repair Information (Systems Operation, Testing and Adjusting, Troubleshooting, Specifications, Disassembly and Assembly) 

1-AIR INLET AND EXHAUST SYSTEM  

1-1 systems Operation

3064 and 3066 Engines for Caterpillar Built Machines - SENR5546

Air Inlet and Exhaust System

SMCS - 1050

 

Air Inlet and Exhaust System Schematic

(1) Exhaust manifold
(2) Inlet manifold
(3) Engine cylinder
(4) Air inlet heater
(5) Turbocharger compressor wheel
(6) Turbocharger turbine wheel
(7) Air inlet
(8) Exhaust outlet

(9) Turbocharger 

The components of the air inlet and the components of the exhaust system control the quality of available air for combustion. The components of the air inlet and the components of the exhaust system also control the amount of available air for combustion. The air inlet and the exhaust system consist of the following components:

• Air cleaner
• Inlet manifold
• Cylinder head
• Valves
• Valve components
• Exhaust manifold
• Turbocharger

Turbocharger compressor wheel (5) pulls clean inlet air from the air cleaner through air inlet (7). The rotation of turbocharger compressor wheel (5) causes compression of the air and the rotation of the turbocharger compressor wheel forces the air through inlet manifold (2) to the inlet valves in the cylinder head. The inlet valves control the air flow into each engine cylinder.
There is one inlet and one exhaust valve for each cylinder. Refer to "Valves and Valve System Components". The inlet valves open when the piston moves down on the inlet stroke. Compressed air from inlet manifold (2) is pulled into engine cylinder (3). The inlet valve closes. The piston starts to move up on the compression stroke. When the piston is near the top of the compression stroke, fuel is injected into the engine cylinder. The fuel mixes with the air and combustion begins. The force of combustion pushes the piston downward. The piston is pushed downward on the power stroke. The piston moves up again on the exhaust stroke. The exhaust valve opens and the exhaust gases are pushed through the exhaust port into exhaust manifold (1). After the piston makes the exhaust stroke, the exhaust valve closes and the cycle starts again. The cycle consists of the following items: inlet, compression, power and exhaust.
Exhaust gases from exhaust manifold (1) go into the turbine side of turbocharger (9) and the exhaust gases cause turbocharger turbine wheel (6) to turn. Turbocharger turbine wheel (6) and turbocharger compressor wheel (5) are connected to the same shaft. The exhaust gases travel through the exhaust outlet (8). The exhaust gases travel through the exhaust system.

Turbocharger

Left side view of the 3066 Engine

(1) Turbocharger (2) Exhaust manifold 

Turbocharger (1) is installed on the center of the exhaust manifold (2). All of the exhaust gases from the engine travel through turbocharger (1). The compressor side of turbocharger (1) is connected to the elbow of the air heater of the inlet manifold by a rubber hose. 

Turbocharger


(3) Air inlet
(4) Compressor housing
(5) Compressor wheel
(6) Bearing
(7) Oil inlet port
(8) Bearing
(9) Turbine housing
(10) Turbine wheel
(11) Exhaust outlet
(12) Oil outlet port
(13) Exhaust inlet 

The exhaust gases travel into the turbine housing (9) through exhaust inlet (13). The exhaust gases push the blades of turbocharger turbine wheel (10). Turbocharger turbine wheel (10) and turbocharger compressor wheel (5) have the same shaft.
Clean air from the air cleaners is pulled through the air inlet (3) of the compressor housing by the rotation of the turbocharger compressor wheel (5). The inlet air is compressed by the movement of the blades of the compressor. The compression allows the engine to burn more air and fuel during combustion. The result is greater power for the engine.
More fuel is injected into the cylinders when the load on the engine increases. More exhaust gases are produced and turbocharger turbine wheel (10) and turbocharger compressor wheel (5) of the turbocharger turn faster. More air is forced into the engine as turbocharger compressor wheel (5) turns faster. The engine burns more fuel with greater efficiency because of the increased air flow. More engine power is the result.
The maximum rpm of the turbocharger is controlled by the fuel setting, the high idle speed setting, and the height above sea level of the engine.

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NOTICE

If the fuel setting is higher than given in the TMI (Technical Marketing Information), there can be damage to engine or turbocharger parts. Damage will result when increased heat and/or friction due to the higher engine output goes beyond the engine cooling and lubrication systems abilities. A mechanic that has the proper training is the only one to make the adjustment of fuel setting and high idle rpm setting.

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The fuel setting adjustment is performed at the factory for a specific engine application. The governor housing is sealed in order to prevent changes in the adjustment of the fuel. The governor housing is also sealed in order to prevent changes of the high idle speed setting.
Bearing (6) and bearing (8) of the turbocharger use engine oil under high pressure for lubrication. The oil passes through the oil inlet port (7). The oil then travels through the passages in the center section for the lubrication of the bearings. Oil from the turbocharger travels through the oil outlet port (12) in the bottom of the center suction. The oil then travels back to the engine lubrication system. 

Valves and Valve System Components

The valves and the valve system components control the flow of inlet air into the cylinder during engine operation. The valves and the valve system components also control the flow of exhaust gases out of the cylinder during engine operation.

Valve System Components

(1) Rocker arm
(2) Valve retainer
(3) Valve cap
(4) Adjusting screw
(5) Pushrod
(6) Valve spring
(7) Valve guide (8) Valve 

The inlet and exhaust valves are opened and the inlet and exhaust valves are closed by the movement of the following components: crankshaft, camshaft, tappets, pushrods, rocker arms and valve springs. Rotation of the crankshaft causes rotation of the camshaft. The camshaft gear is timed to a gear on the front of the crankshaft. The camshaft gear is also driven by the gear on the front of the crankshaft. The rotation of the camshaft causes the lobes to rotate. The rotation of the lobes of the camshaft cause the tappets to move. The movement causes pushrod (5) to move rocker arm (1). Movement of rocker arm (1) causes the inlet and exhaust valves to open according to the firing order (injection sequence) of the engine. Valve spring (6) for each valve makes the valve return to the closed position. The valve spring also holds the valve closed.  

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