ENGINE AR 3192121 - Caterpillar

Illustration 4 g02469997
Typical example
(12) Wastegate actuator
(13) Actuating lever
(14) Line (boost pressure)
Illustration 5 g02151895
Typical example
(15) Wastegate regulator When the load on the engine increases, more fuel is injected into the cylinders. The combustion of this additional fuel produces more exhaust gases. The additional exhaust gases cause the turbine and the compressor wheels of the turbocharger to turn faster. As the compressor wheel turns faster, air is compressed to a higher pressure and more air is forced into the cylinders. The increased flow of air into the cylinders allows the fuel to be burnt with greater efficiency. This produces more power.A wastegate is installed on the turbine housing of the turbocharger. The wastegate is a valve that allows exhaust gas to bypass the turbine wheel of the turbocharger. The operation of the wastegate is dependent on the pressurized air (boost pressure) from the turbocharger compressor. The boost pressure acts on a diaphragm that is spring loaded in the wastegate actuator which varies the amount of exhaust gas that flows into the turbine.The wastegate regulator (15) is controlled by the engine Electronic Control Module (ECM). The ECM uses inputs from a number of engine sensors to determine the optimum boost pressure. This will achieve the best exhaust emissions and fuel consumption at any given engine operating condition. The ECM controls the wastegate regulator, that regulates the boost pressure to the wastegate actuator.When higher boost pressure is needed for the engine performance, a signal is sent from the ECM to the wastegate regulator. The wastegate regulator reduces the pressure in the air inlet pipe (14) that acts upon the diaphragm within the wastegate actuator (12).The spring within the wastegate actuator (12) forces the wastegate valve that is within the turbine housing to close via the actuating rod and lever. When the wastegate valve is closed, more exhaust gas is able to pass over the turbine wheel. This results in an increase in turbocharger speed and boost pressure generation.When lower boost pressure is needed for the engine performance, a signal is sent from the ECM to the wastegate regulator. This causes high pressure in the air inlet pipe (14) to act on the diaphragm within the wastegate actuator (12). The actuating rod (13) acts upon the actuating lever to open the valve in the wastegate. When the valve in the wastegate is opened, more exhaust gas from the engine is able to bypass the turbine wheel. The exhaust gases bypass the turbine wheel results in a decrease in the speed of the turbocharger.The shaft that connects the turbine to the compressor wheel rotates in bearings (4) and (6). The bearings require oil under pressure for lubrication and cooling. The oil that flows to the lubricating oil inlet port (5) passes through the center of the turbocharger which retains the bearings. The oil exits the turbocharger from the lubricating oil outlet port (10) and returns to the oil pan.Crankcase Breather
The engine crankcase breather is a filtered system. The crankcase breather system consists of two main elements,