PLATE 3153778 - Caterpillar

Inlet Air Choke
Illustration 6 g00488519
Inlet Air Choke (1) Actuator. (2) Adjustable linkage. (3) Turbocharger outlet. (4) Aftercooler. (5) Choke plate.The air (choke) actuator (1) is one of three actuators that is used to control the air/fuel ratio of the engine. One actuator controls fuel flow. The other two actuators work together in order to control the amount of air that is supplied to the engine throughout the entire speed and load range. The actuator is located on the left rear of the engine. The actuator receives an electronic signal from the Engine Control Module. The actuator mechanically changes the position of the air choke plate (5) via an actuator lever and adjustable rod (2) .The position of the plate is represented by the slot that is cut into the end of the shaft. The movement of the choke plate controls the air flow from the turbocharger outlet, through the inlet air choke. The air will then flow through the aftercooler into the cylinder block air plenum, and then into the cylinder head. Fuel is introduced to the air in the cylinder head by the gas admission valve.At full load and full speed, the actuators will operate the engine with the air choke in the fully open position. This in order to reduce the restriction to the air flow and improve the engine operating efficiency. The ECM will use the exhaust bypass system in order to control the air/fuel ratio of the engine. As engine load decreases, the inlet air choke begins to restrict air flow into the air plenum of the cylinder block. This is done in order to maintain a sufficiently rich mixture for good combustion at lighter engine loads. This combination of control (exhaust bypass/inlet air choke) provides for the increased improvement in fuel consumption at part load conditions, while also allowing complete control at full load conditions. Exhaust Manifold
The exhaust manifold is a dry design that utilizes a thermal blanket for reduced radiant heat rejection. A dry manifold is possible because of the inherently low exhaust manifold temperatures of lean burn combustion. Engine performance is enhanced, especially for constant torque and variable speed industrial applications, by retaining the exhaust system energy in order to drive the turbocharger.Valve System Components
Illustration 7 g00328157
Valve System Components (1) Rocker arm. (2) Gas admission valve rocker arm linkage. (3) Bridge. (4) Gas admission valve. (5) Pushrod. (6) Lifter.The valve system components control the flow of inlet air, fuel and exhaust gases into the cylinders and out of the cylinders during engine operation.The crankshaft gear drives the camshaft gears through idler gears. The camshafts must be timed to the crankshaft in order to get the correct relation between the piston and the valve movement.The camshaft has three camshaft lobes for each of the cylinders. One lobe operates the bridge that moves the two inlet valves. One lobe operates the bridge that moves the two exhaust valves. The center lobe operates