The ignition system has five basic components: magneto, an ignition transformer for each cylinder, wiring harness, spark plugs and control panel.
The magneto generates the electric current that is necessary for spark ignition. The current from the magneto travels through the wiring harness to the ignition transformer. The transformer increases the voltage. The transformer creates an electrical impulse that arcs across the electrodes of the spark plug. Engine operation is monitored by the control panel.
Inlet air is filtered by an air cleaner. G3406 Engines are also available with these types of aspiration: naturally aspirated, turbocharged, turbocharged with separate circuit aftercooling and turbocharged with air-to-air aftercooling.
For turbocharged engines, the inlet air is compressed by the turbocharger. The turbocharger is driven by the engine exhaust. The air is cooled in an aftercooler (if equipped) before the air enters the carburetor. The air becomes more dense from compression and cooling. This provides more oxygen for combustion.
Air is mixed with fuel in the carburetor before combustion. The carburetor is controlled by a governor. The governor efficiently maintains the engine rpm that is selected by the operator.
The valves and the valve mechanism control the flow of air and exhaust gases in the cylinder during engine operation. Each cylinder has one inlet valve and one exhaust valve. The camshaft actuates the rocker arms and valves through mechanical lifters and pushrods.
The engine lubrication oil is circulated by a gear-driven pump. The oil is cooled and the oil is filtered. However, bypass valves provide an unrestricted flow of lubrication oil to the engine if the following conditions occur:
- The viscosity of the oil is high because the oil is cold.
- The oil cooler becomes plugged.
- The oil filter becomes plugged.
The jacket water coolant is circulated by a gear-driven centrifugal pump. A
For engines with a Separate Circuit Aftercooler (SCAC), the air is cooled by a heat exchanger. The water that cools the air in the heat exchanger is in a circuit that is separate from the jacket water. The aftercooler coolant is pumped by an auxiliary water pump. The SCAC is required to operate at one of the following temperatures. The engine rating depends on the temperature and the application.
-
32 °C (90 °F) -
54 °C (129 °F)
For engines with air-to-air aftercooling, the aftercooler is supplied by the customer. This aftercooler is similar to a radiator. The inlet air is cooled by a fan that moves the ambient air through the radiator.
Engine efficiency and maximum utilization of engine performance depend on adherence to proper operation and maintenance recommendations. This includes the use of recommended lubricants, fuels, and coolants.
For the engine maintenance that is required, refer to this Operation and Maintenance Manual, "Maintenance Interval Schedule" (Maintenance Section).