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| Illustration 1 | g06127327 |
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Cooling system (1) Shunt tank for the radiator (2) Bypass (3) Water Regulator Housing (4) Radiator Cores (5) Vent Line (radiator rear section) (6) Vent Line (radiator front section) (7) Vent Line (engine) (8) Inlet Tube (radiator) (9) Water Pump (10) Engine Oil Cooler (11) Transmission Oil Cooler (12) Turbocharger Oil Lines (13) Turbocharger (14) Shunt Line (AA) Unregulated Coolant (BB) Regulated Coolant | |
Water pump (9) draws coolant directly from radiator (4). The coolant is pumped through the engine oil cooler (10) and the transmission oil cooler (11). From these oil coolers, coolant flows through the engine block.
The coolant goes around the cylinder liners, through the water seals and into the cylinder heads. The water passages inside the cylinder head 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 the regulator housing, two water temperature regulators control the direction of coolant flow within the regulator housing.
When the coolant temperature is below
As the coolant temperature reaches
Note: Water temperature regulators inside the regulator housing (3) are an important part of the cooling system. Water temperature regulators (3) divides the coolant flow between radiator (4) and bypass (2). Normal operating temperature is maintained. If the water temperature regulators are 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. On cold days the engine may overcool.
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| Illustration 2 | g06127372 |
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(15) Steering Oil Cooler
(16) Axle Oil Cooler (17) Aftercooler (18) Hydraulic Oil Cooler (19) Air Conditioner Condenser | |
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| Illustration 3 | g06127359 |
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(5) Vent Line (rear section)
(6) Vent Line (front section) (20) Radiator Cores (21) Radiator Bottom Tank | |
The radiator is the cooling source of coolant for the cooling system. The radiator is made up of the following three sections. shunt tank for the radiator (1), radiator bottom tank (7), and radiator core assembly (6).
The shunt tank (1) for the radiator is separate from the radiator. The tank is used in order to fill the cooling system, provides space for coolant expansion and removes air/gas from the system. Shunt line (14) connects to the shunt tank (1) to the inlet of the engines water pump (9). The shunt line provides a positive head pressure to the water pump as well and prevents cavitation. Coolant flows to the engine through the shunt line.
The radiator bottom tank (21) is divided into two sections. The rear section accepts the return coolant from the water regulator housing (3). The front section is connected to the inlet of the water pump (9).
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 (21). 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 inside 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.
Radiator vent lines implemented to remove air or gas trapped in the cooling system. Vent line (radiator rear section) (5) removes gas from the highest point of the rear of the radiator cores (20). Vent line (radiator front section) (6) removes gas from the highest point of the front of the radiator cores (20) . Vent line (engine) (7) removes air and gas from the highest point of the engine.
Reference: For additional information about the refrigerant condenser, refer to the Service Manual module Systems Operation, SENR5664, "Air Conditioning and Heating R-134a All Caterpillar Machines".
Reference: For additional information about cooling the hydraulic system, refer to the Service Manual module Systems Operation, KENR7599, "Hydraulic Fan System".
Reference: For additional information about cooling the steering system, refer to the Service Manual module Systems Operation, KENR7591, "General Information".
Reference: For additional information about the axle oil cooler, refer to the Service Manual module Systems Operation, KENR7585, "Axle Oil Cooler".
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| Illustration 4 | g06127432 |
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Rear Left Side of the Machine (10) Engine Oil Cooler (22) Bonnet (9) Water Pump (23) Bonnet (24) Oil Inlet (11) Transmission Oil Cooler (25) Oil Outlet (26) Bonnet | |
Engine coolant from water pump (9) flows through bonnets (22) and (26) to oil cooler (11). The coolant flows through long tubes inside the oil cooler to bonnet (23). The coolant then flows through bonnet (23) 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 (24) to the inside 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 (25). This oil has a lower temperature than the inlet oil. The oil now flows through a line in order to lubricate the planetary group.
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| Illustration 5 | g06132814 |
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Air to air aftercooler (3) Aftercooler (27) Air Cleaners (28) Inlet Piping to The ATAAC Core (29) Inlet Piping From The ATAAC Core (30) Exhaust (31) Turbocharger (32) Muffler (33) Precleaners (AA) Inlet Air (BB) Exhaust Gases | |
The air-to-air aftercooled (ATAAC) system provides cool air to the air intake manifold on top of the engine. Clean inlet air is pulled through the air cleaners (27) by the turning of the compressor wheel which is connected to the turbine wheel of the turbochargers (31). The compressor wheel causes a compression of this air which allows a larger volume of air to be drawn into the combustion chamber of the engine. This compressed air is referred to as manifold or boost pressure. This compression also causes the temperature of the air to increase and become less dense.
The inlet air is sent through air inlet piping (28) to the aftercooler (3) where it flows through internal tubes of the cooler core. Ambient air temperature flows across the core cooling the inlet air temperature. This cooling of the inlet air causes the air to become denser and allows more volume of air to be forced into the combustion chamber. This increases the combustion efficiency and the horsepower output of the engine.
Through air inlet piping (29) the air then flows from the aftercooler (3) to the air intake manifold on top of the engine. There are inlet and exhaust ports on the cylinder head which allows boost pressure to enter the combustion chamber. Two inlet and two exhaust valves for each cylinder are controlled by the engines camshaft. The camshaft is timed to the engines crankshaft that allows the inlet air, exhaust gases, and fuel to be timed with the piston position.
Just before the piston reaches the top of the exhaust stroke the exhaust valves start to close and the inlet valves start to open. The process of the intake stroke then begins. With the inlet valves open and exhaust valves closed, the piston starts downward on the inlet stroke allowing the compressed/cool air to be drawn into the combustion chamber. The inlet air will continue to fill the combustion chamber until the piston just reaches the bottom of the intake stroke
As the piston starts to reach the end of the intake stroke the inlet valves start to close. The compression stroke then begins. With the exhaust valves already closed and inlet valves finish closing the piston. The piston starts the travel upward on the compression stroke causing the combustion air to be compressed to a very high temperature.
Just before the piston reaches the top of the compression stroke and both intake and exhaust valves closed, fuel is injected into the combustion chamber. The power stroke then begins . With the heat of compression and the atomization of the fuel, combustion starts in the combustion chamber. Once combustion starts the expanding gases force the piston downward towards the bottom of the power stroke.
Just as the piston reaches the end of the power stroke the exhaust valves start to open. The exhaust stroke then begins . As the piston starts its upward travel and both exhausts open and both inlet valves are closed the exhaust gases are pushed out of the combustion chamber and into the exhaust manifold. At the end of the exhaust stroke the exhaust valves start to close and the intake valves starts to open the cycle starts again.
When the exhaust valves open, the exhaust gases flow out of the engine combustion chambers and into exhaust manifolds. From the exhaust manifolds, the high-pressure exhaust gases flow across the blades of the turbine wheel in the turbochargers. This causes the turbine wheel to spin. The turbine wheel is connected to the compressor wheel causing it to turn creating manifold or boost pressure. From the turbocharger, exhaust gases flow to the muffler, and then to the exhaust piping (30).
Reference: For 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.
Turbocharger (31) has one inlet and one outlet. Turbocharger oil lines (12) are connected to the turbocharger at these ports. Pressurized engine oil flows from the main oil gallery of the engine into turbocharger (31) through turbocharger oil lines (12). 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 (12) into the oil pan on the bottom of the engine.