| Tweet |
Custom Search
|
|
|
||
 TM 5-2010-205-14
Section III. PRINCIPLES OF OPERATION
1-12. GENERAL.
a. The diesel engine is an internal combustion power unit, whereby energy of burning fuel is converted into work in
the cylinders of the engine.
b. In the diesel engine, air is compressed in the cylinders. After the air has been compressed, a charge of fuel is
sprayed into the cylinders. Ignition is accomplished by the heat of compression.
1-13. BASIC BLOCK.
a. Cylinder Block. The cylinders are a part of the cylinder block. There are no replaceable cylinder liners. The
cylinders can be machined (bored) up to .040 in. (1.02 mm) oversize for reconditioning. The cylinders are arranged in
two (2) banks of four (4) cylinders each. The cylinder banks are at 90 degree angles to each other. There are five main
bearings in the block to support the crankshaft.
b. Cylinder Head and Valves.
(1). There is one cylinder head for each side (bank) of the engine. One intake and one exhaust valve is used for
each cylinder. The valve guides are a part of the cylinder head and cannot be replaced. A valve seat insert is used for
the exhaust valve and can be replaced.
(2). The valves and valve system components control the flow of inlet air and exhaust gases into and out of
each cylinder during engine operation.
(3). The intake and exhaust valves are opened and closed by movement of the crankshaft, camshaft, cam
followers, push rods, rocker arms and valve springs. Rotation of the crankshaft causes rotation of the camshaft. The
camshaft gear is driven by, and timed to, a gear on the front of the crankshaft. When the camshaft turns, the cams on
the camshaft cause the cam followers to go up and down. This movement makes the push rods move the rocker arms.
The movement of the rocker arms will make the intake and exhaust valves in the cylinder head open and close according
to the firing order (injection sequence) of the engine. Two valve springs for each valve help to hold the valves in the
closed position.
(4). There is one intake and one exhaust valve for each cylinder. The valve seat for the intake valve is
machined in and part of the cylinder head. The valve guide bore is machined in and a part of the cylinder head.
1-8
|
||
|
||
