Water Cooling System of GM Locomotive
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Questions and Answers

What is the primary purpose of the pressure cap in the cooling system?

  • To relieve excessive pressure (correct)
  • To add coolant automatically
  • To filter corrosion inhibitors
  • To maintain coolant temperature

    • What happens if the low water level switch opens while the engine is running?

  • The engine automatically shuts down
  • A crew message is displayed and an alarm rings (correct)
  • The coolant is replaced automatically
  • The cooling system pressure is released

    • Which of the following is NOT a requirement for coolant suitable for use in EMD engines?

  • Adequately transfer heat energy
  • Not deteriorate seals or gaskets
  • Prevent corrosion inside the cooling system
  • Can promote scale accumulation (correct)

    • How is borate-nitrate type corrosion inhibitor meant to be prepared before adding to the cooling system?

    <p>Dissolved in water in a separate container</p> Signup and view all the answers

    What is the ideal concentration level that the borate-nitrate inhibitor should be maintained at?

    <p>5625 parts per million</p> Signup and view all the answers

    What condition prompts the engine to not be allowed to start?

    <p>Low water level detected while engine is stopped</p> Signup and view all the answers

    In addition to water, which component is essential for effective coolant function?

    <p>Corrosion inhibitor</p> Signup and view all the answers

    What temperature range is maintained for the coolant according to the cooling fan system?

    <p>79°C to 85°C</p> Signup and view all the answers

    What does the operating water level instruction plate indicate?

    <p>Water level thresholds with engine running or stopped</p> Signup and view all the answers

    At what coolant temperature will the engine speed increase to TH-2?

    <p>Below 46°C</p> Signup and view all the answers

    Which is a consequence of allowing the water level to drop below the LOW mark?

    <p>Potential system damage</p> Signup and view all the answers

    What happens when the engine coolant temperature exceeds 97°C?

    <p>Power and RPM are reduced to the 6th notch</p> Signup and view all the answers

    What happens if both electronic temperature sensing probes fail?

    <p>Signals from the probes are ignored and engine speed returns to idle.</p> Signup and view all the answers

    What does the vacuum breaker on the pressure cap do?

    <p>Minimizes the risk of vacuum formation</p> Signup and view all the answers

    What is the primary purpose of the cooling system pressurization?

    <p>To raise the boiling point of the coolant</p> Signup and view all the answers

    What message is displayed when the engine coolant temperature becomes excessively high?

    <p>HOT ENGINE - THROTTLE 6 LIMIT</p> Signup and view all the answers

    Where are the radiator banks located in the locomotive?

    <p>In a hatch at the top of the long hood end.</p> Signup and view all the answers

    What is the purpose of the bypass line in the radiator system?

    <p>To reduce velocity in the radiator tubes.</p> Signup and view all the answers

    When the engine speed is raised to TH-2, for how long will it continue if the temperature stays below 52°C?

    <p>As long as the temperature remains below 52°C</p> Signup and view all the answers

    Which color indicates normal coolant temperature on the gauge?

    <p>Green</p> Signup and view all the answers

    How is the water temperature controlled in the cooling system?

    <p>Through radiator banks and AC motor driven cooling fans.</p> Signup and view all the answers

    What is the function of the electronic temperature sensing probes?

    <p>To monitor temperature from the oil cooler to the water pump.</p> Signup and view all the answers

    What type of contractors are involved in the two-speed cooling fan system?

    <p>Two full-speed contractors and one slow-speed contractor</p> Signup and view all the answers

    What happens to the cooling fans when the engine coolant temperature begins to drop?

    <p>They switch to slow speed in progression</p> Signup and view all the answers

    What message is displayed if either of the temperature probes fails?

    <p>ENGINE TEMPERATURE FEEDBACK FAILURE.</p> Signup and view all the answers

    What is the effect of excessive heat on the water pump as detected by the cooling system?

    <p>Increases the risk of pump cavitation</p> Signup and view all the answers

    Which additional component receives cooling water from the water pumps?

    <p>Air compressor.</p> Signup and view all the answers

    What controls the operation of the radiator fans?

    <p>The EM2000 computer acting on contractors.</p> Signup and view all the answers

    What is the purpose of the cooling process within the engine?

    <p>To ensure optimal engine performance and prevent overheating.</p> Signup and view all the answers

    What is the design of the radiator core assemblies?

    <p>Two quad length assemblies bolted end to end.</p> Signup and view all the answers

    Study Notes

    Water Cooling System of GM Locomotive

    • The engine-mounted water pumps draw cooling water from the expansion tank and lube oil cooler assembly, then pump it into the engine.
    • Heated water leaves the engine and flows through two radiator assemblies, where it is cooled.
    • Cooled water then returns through the oil cooler to complete the closed-loop cycle.
    • Part of the water from the water pumps is piped to the air compressor.
    • There are no valves in this line; air compressor cooling is provided whenever the engine is running.

    Flow Diagram of Water Cooling System

    • The diagram shows the components and the flow of water through the system. Critically important components are highlighted.
    • Components include: radiators, expansion tank, lube oil cooler, water pumps, air compressor, ETP-1 & ETP-2, Engine Crank Case, 'Y' manifold, and drain COC.
    • Water pumps draw water from the expansion tank and send it into the engine.
    • The water is heated by the engine and flows through radiators for cooling.
    • The cooled water then returns to the oil cooler, where it is further cooled, and proceeds to the water pumps to restart the cycle.

    Electronic Temperature Sensing Probes

    • Two electronic temperature sensing probes (ETP-1 & ETP-2) are located in the water line from the oil cooler to the water pump on the engine's left side, near the water temperature gauge.

    Engine Temperature Feedback Failure

    • If the EM2000 computer detects a failed temperature probe, it sends a "ENGINE TEMPERATURE FEEDBACK FAILURE" message to the EM2000 display and stores it in the Archive memory.
    • If both probes fail, the computer ignores the signals, the fans remain in last operations status, the engine speed returns to idle, and the "NOT LOADING ENGINE TEMPERATURE FEEDBACK FAILURE" message is stored in Archive memory.

    Radiators and Cooling Fans

    • During circulation through the diesel engine, air compressor, and oil cooler, coolant picks up heat, requiring heat dissipation.
    • Water temperature is regulated by radiator banks and AC motor-driven cooling fans.
    • Radiators are located in a hatch at the top of the locomotive's long hood.
    • Each bank has two quad-length radiator core assemblies bolted end-to-end.

    Headers and Bypass Lines

    • Headers are mounted on the radiator core to create the inlet and outlet ends of the radiator assembly.
    • A bypass line is present between the inlet and outlet lines to reduce velocity in the radiator tubes.
    • Cooling water from the engine is piped to the headers of each radiator bank.
    • The radiators' discharge enters the oil cooler, then returns to the water pumps for recirculation.

    Radiator Fans

    • Eight-blade, 52" cooling fans are controlled by the computer, which acts on the contractors.
    • The computer controls fan sequencing, duty cycle, and speed (low and high) to ensure even fan and contractor wear.
    • The two-speed cooling fan system includes two full-speed contractors (FCFA & FCFB) and one slow-speed contractor (FCS) per cooling fan motor.
    • The system maintains coolant temperature within a predetermined range of 79°C to 85°C.
    • Fans are driven by a two-speed AC motor powered by the companion alternator.
    • Fans are energized in sequence by the control computer (slow speed) and may switch to full speed as additional cooling is needed. Coolant temperature drops initiate fan shutdown sequentially.

    Speed Due to Cold Engine

    • If the ETP-1 & ETP-2 detects the temperature is below 46°C, the engine speed is raised to TH-2.
    • The engine runs at TH-2 as long as the temperature stays below 52°C.
    • Once the temperature exceeds 52°C, engine speed returns to idle.

    Hot Engine Condition

    • Engine cooling water temperature is sensed at the water pump inlet.
    • Excessive temperature results in a "HOT ENGINE-THROTTLE 6 LIMIT" message (Temp.-97°C).
    • The computer limits engine loading when operating in throttle positions 7 or 8 under high temperature conditions.
    • This condition remains until the temperature returns to a safe limit.

    Temperature Gauge

    • A color-coded temperature gauge is located on the water pump inlet line.
    • The gauge has three colors: COLD (blue), NORMAL (green), and HOT (red).

    Cooling System Pressurization

    • The cooling system is pressurized to elevate coolant boiling point, allowing higher engine operating temperatures with minimal coolant loss due to boiling.
    • Pressurization also ensures uniform water flow, minimizing water pump cavitation during temperature fluctuations.

    Pressure Cap

    • A pressure cap on the water tank filler pipe opens at approximately 20 PSI, relieving excessive pressure to prevent damage to cooling system components.
    • The pressure cap also features a vacuum breaker to minimize damage caused by vacuum pulling during cooling.

    Operating Water Level

    • An operating water level instruction plate next to the water level sight glass gives LOW (minimum) and FULL (maximum) water levels for engine running or when the engine is shut off.
    • Water level should not go below the applicable LOW water mark

    Water Level Switch

    • A water level switch (float type) is installed in the cooling system water tank (connected to DIO 1 input channel 7 labeled NO LWL).
    • When the engine runs and the water level switch is open for 10 seconds, the "LOW ENGINE WATER LEVEL DETECTED" message displays, and the alarm sounds for 60 seconds to alert the crew.
    • This fault is archived if detected while the engine is shut down, preventing engine startups and displaying "ENGINE WATER LEVEL DETECTED" for 60 seconds.

    Coolant

    • Coolant circulates through the engine to transfer heat from engine components to the radiators.
    • Engine coolant is composed of water, corrosion inhibitor, and antifreeze (if needed).
    • Coolant samples should be taken and analyzed regularly to maintain proper corrosion inhibitor solution.

    Coolant Requirements for EMD Engines

    • Coolant suitable for EMD engines must adequately transfer heat, not form scale or sludge, prevent corrosion, and not deteriorate seals or gaskets.

    Corrosion Inhibitor

    • The primary corrosion inhibitor for EMD engines is the borate-nitrate type.
    • Borate-nitrate is available in powder and liquid form. The powder or pellet forms need mixing and dissolving in water before adding to the cooling system.
    • The concentration of borate-nitrate should be maintained above 5625 parts per million.

    Water Pump

    • Water pumps are impeller pumps that draw coolant from the bottom of the radiator and force it to the water jacket.
    • The pump's drive shaft is supported by permanently sealed grease-lubricated bearings, requiring no maintenance.

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    Related Documents

    GM Locomotive Water Cooling System PDF

    Description

    Explore the intricate water cooling system of the GM locomotive, including the function of engine-mounted water pumps and radiator assemblies. This quiz will guide you through the flow diagram and critical components involved in the cooling process. Test your knowledge on how heated water is managed in an efficient closed-loop cycle.

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