THEORY OF OPERATION: INTRODUCTION
This work package provides a brief functional description of the major systems and components found on the D7R
The D7R Dozer is an earth-moving machine with a bulldozing attachment that cuts, moves, and grades material
through forward motion of the machine. A 10.3L diesel engine powers the D7R Dozer. Additional implements for
the machine include a hydraulically operated ripper and a towing winch. A dozer will have only one implement, not
Refer to the Theory of Operation work packages for information about the following systems:
ENGINE AND FUEL
The 3176C engine has an in-line six cylinder arrangement with a bore of 4.92 inch (125.0 mm) and a
stroke of 5.51 inch (140.0 mm). The displacement is 629 cu. in. (10.3 L). The engine has a firing order
sequence of: 1, 5, 3, 6, 2, and 4. The rotation of the engine is counterclockwise when the engine is viewed
from the flywheel end. The engine utilizes a turbocharger and a water jacket aftercooler.
The following engine components are described: Cylinder block, Pistons, Rings, Connecting Rods, Crank-
shaft, Camshaft, Vibration damper, and Rear power take-off (RPTO).
The 3176C engine incorporates a high pressure electronic unit injector system and an electronic control
system. The features enhance engine speed control, cold starting capabilities, and lower the smoke level
for emissions under all operating conditions.
The Electronic Unit Injector system eliminates many of the mechanical components that are traditionally
used in the fuel injector assembly. The Electronic Unit Injector (EUI) provides increased control of the tim-
ing and the fuel air mixture. The timing advance is achieved by precise control of the fuel injection timing.
Engine rpm is controlled by adjusting the injection duration. A special pulse wheel provides information to
the engine Electronic Control Module (ECM) for detection of cylinder position and engine rpm.
The engine has built-in diagnostics in order to ensure that all of the components are operating properly. In
the event of a system component failure, the operator will be alerted to the condition by a check engine
light, located on the dashboard. An electronic service tool can be used to read the numerical code of the
faulty component or condition. Intermittent faults are logged and stored in memory.
The fuel system is subdivided into the following systems: electronic unit injector, low pressure fuel, elec-
tronic controls, and injector actuation.
AIR INLET AND EXHAUST
The components of the air inlet and exhaust system conrol the quality of air and the amount of air that is
available for combustion. The major components of the air inlet and exhaust system are: Air cleaner, Tur-
bocharger, Aftercooler, Cylinder head, Valves and valve system components, Piston and cylinder, and
The lubrication system supplies 230 °F (110 °C) filteed oil at approximately 40 psi (275 kPa) at rated
engine operating conditions. The engine oil pump is mounted to the back of the front gear train on the
lower right hand side of the engine.