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| Illustration 1 | g02729735 |
Cooling system (1) Shunt tank for the radiator (2) Bypass (3) Water regulator housing (4) Radiator cores (5) Turbocharger (6) Turbocharger oil lines (7) Transmission oil cooler (8) Engine oil cooler (9) Water pump (10) Inlet tube (radiator) (AA) Unregulated coolant (BB) Regulated coolant | |
Water pump (9) draws coolant directly from radiator (4). The coolant is pumped through the engine oil cooler (8) and the transmission oil cooler (7). From these oil coolers, coolant flows through the engine block.
The coolant goes around the cylinder liners, through the water directors and into the cylinder heads. The water directors send the flow of coolant around the valves and the passages for exhaust gases in the cylinder heads. The coolant then goes to the front of the cylinder heads and into water regulator housing (3). When the coolant is inside of housing (3), two water temperature regulators control the direction of coolant flow within housing (3) .
When the coolant temperature is below 81 °C (178 °F), water temperature regulator (3) will be closed. The path for the coolant return to radiator (4) is blocked. The coolant flows through regulator housing (3). Then, the coolant is fed back to the inlet of water pump (9) .
As the coolant temperature reaches 82° ± 1°C (180° ± 2°F), water temperature regulator (3) starts to open. Coolant begins to flow to tube (10). When the coolant temperature reaches 92 °C (198 °F), the coolant is at normal operating temperature. Water temperature regulator (3) is fully open and the flow of coolant to bypass (2) is blocked. The path for the coolant to radiator (4) through the tube (10) is open. The temperature of the returned coolant will be reduced as the coolant flows through radiator (4).
Note: Water temperature regulator (3) is an important part of the cooling system. Water temperature regulator (3) divides the coolant flow between radiator (4) and bypass (2). Normal operating temperature is maintained. If the water temperature regulator is not installed in the system, the flow of coolant is not regulated. Most of the coolant will go through the bypass (2) and bypass radiator assembly (4). The engine, the transmission, and the hydraulic oil may overheat during high ambient temperatures.
Turbocharger (5) has one inlet and one outlet. Turbocharger oil lines (6) are connected to the turbocharger at these ports. Pressurized engine oil flows from the crankcase of the engine into turbocharger (5) through turbocharger oil lines (6). This engine oil is used for lubrication of the bearings in the turbocharger and for cooling of the turbocharger. The oil then drains through turbocharger oil lines (6) into the oil pan on the bottom of the engine.
Radiator Assembly
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| Illustration 2 | g01450190 |
(1) Steering oil cooler (2) Axle oil cooler (3) Aftercooler (4) Hydraulic oil cooler (5) Air conditioner condenser | |
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| Illustration 3 | g01450633 |
(6) Radiator cores (7) Radiator bottom tank | |
The radiator is the source of coolant for the cooling system. The radiator is made up of the following three sections. shunt tank for the radiator, radiator bottom tank and radiator core assembly.
The shunt tank for the radiator is separate from the radiator. The tank is used in order to fill the cooling system.
The radiator bottom tank is divided into two sections. The rear section accepts the return coolant from the water regulator housing. The front section is connected to the inlet of the water pump.
The radiator core assembly is made up of two paths with a connection between the paths at the top of each core. As the coolant is returned to the radiator, the coolant flows into the rear section of the bottom tank. The coolant flows up the core through the rear three tubes. As the coolant gets to the top of the core, the coolant flows through the crossover tank. Then, the coolant flows through the three front tubes to the front section of the bottom tank.
As the coolant flows through the radiator cores in both directions and the air is pulled around the radiator core, the temperature of the coolant will be reduced.
Also, the radiator assembly consists of the refrigerant condenser, the hydraulic oil cooler, the steering oil cooler, the axle oil cooler, the fuel cooler, and the aftercoolers.
ReferenceFor additional information about the refrigerant condenser, refer to the Service Manual module Systems Operation, SENR5664, "Air Conditioning and Heating R-134a All Caterpillar Machines ".
ReferenceFor additional information about cooling the hydraulic system, refer to the Service Manual module Systems Operation, KENR7599, "Hydraulic Fan System".
ReferenceFor additional information about cooling the steering system, refer to the Service Manual module Systems Operation, KENR7591, "General Information".
ReferenceFor additional information about the axle oil cooler, refer to the Service Manual module Systems Operation, KENR7585, "Axle Oil Cooler".
Transmission Oil Cooler
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| Illustration 4 | g01450646 |
Rear Left Side of the Machine (1) Engine oil cooler (2) Bonnet (3) Water pump (4) Bonnet (5) Oil inlet (6) Transmission oil cooler (7) Oil outlet (8) Bonnet | |
Engine coolant from water pump (3) flows through bonnets (2) and (8) to oil cooler (6). The coolant flows through long tubes inside the oil cooler to bonnet (4). The coolant then flows through bonnet (4) to the engine cylinder block.
Transmission oil with a high temperature flows from the torque converter outlet to the oil cooler. This oil flows through oil cooler inlet (5) to the inside of the cooler. In this procedure, heat is removed from the oil and the heat is transferred to the coolant in the tubes. The engine coolant is then cooled by the cooling system of the engine.
After the oil flows around the tubes, the oil flows to the other end of the oil cooler. The oil then flows out of the oil cooler through oil cooler outlet (7). This oil has a lower temperature than the inlet oil. The oil now flows through a line in order to lubricate the planetary group.
Air to Air Aftercooler
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| Illustration 5 | g02729766 |
Air to air aftercooler (1) Aftercooler (2) Air cleaners (3) Cooled air enters the air intake manifold on top of the engine. (4) Muffler (5) Turbocharger (AA) Inlet air (BB) Exhaust gases | |
The air-to-air aftercooler system (ATAAC system) provides cooled air to air intake manifold (3) on top of the engine. Air is drawn in through air cleaners (2) and into turbocharger (5). The air is sent through the tube into aftercooler core (1). From core (1), the air flows into the air intake manifold (3) on the top of the engine. The air flow from the inlet port into the cylinders is controlled by inlet valves. Each cylinder has inlet valves and exhaust valves in the cylinder head. The inlet valves open when the piston moves downward on the inlet stroke. When the inlet valves open, cooled compressed air from the inlet port within the inlet manifold is pulled into the cylinder. The inlet valves close when the piston begins to move up on the compression stroke. The air in the cylinder is compressed and the fuel is injected into the cylinder when the piston is near the top of the compression stroke. Combustion begins when the fuel mixes with the air. The force of combustion pushes the piston downward on the power stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port.
Exhaust gases from the exhaust manifold flow into the turbine side of the turbocharger (5). The high-pressure exhaust gases cause the turbocharger turbine wheel to rotate. The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from turbocharger (5) pass through the exhaust outlet, through a muffler (4), and through an exhaust stack.
The efficiency of the engine will increase due to the cooler inlet air. The cooler inlet air will allow lowered fuel consumption, increased horsepower output, and lower emissions from the engine.
ReferenceFor additional information about the turbocharger, refer to the Service Manual module Systems Operation, Testing and Adjusting, "Air Inlet and Exhaust System" for the engine that is being serviced.