TM 5-3805-294-23-1
FIELD MAINTENANCE
THEORY OF OPERATION
SCOPE
This section explains how components of the HYEX work together. A functional description is given for the engine,
electrical system, hydraulic system, fuel system, and cooling system.
HYEX THEORY OF OPERATION
ENGINE
Description
The engine is a John Deere 6068H, PowerTech Plus, 6.8L, 6-cylinder diesel engine. The 6068H includes a
turbocharger, power bulge, electronic control, 4-valve per cylinder head, and a high-pressure common rail fuel
system. The 6068H is air-to-air aftercooled to help reduce exhaust emissions while maintaining low-speed torque.
The engine application includes a hydraulically-driven, cool-on-demand fan system.
Direct fuel injection is provided by a high-pressure pump with common rail and electronic injectors mounted in
cylinder head. The camshaft and high-pressure fuel pump are timed to the crankshaft by the timing gear train.
The turbocharger uses energy from exhaust gases to compress intake air and force it into the combustion chamber.
The cylinder block (Figure 1, Item 1) is a one-piece casting.
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8
9
6
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4
6
7
13
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5
12
2
10
4
11
1
15
3
HYEX01675
Figure 1.
General Engine Operation.