Fuel Oil System and Positive Displacement Pumps
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Questions and Answers

What is the primary purpose of the adjustable calibrating slide on a Mechanical Unit Injector (MUI)?

  • To monitor fuel volume
  • To control the fuel back pressure
  • To adjust injector output (correct)
  • To filter out contaminants

    • What component establishes a fuel back pressure of 15 PSI for the injectors?

  • Relief valve (correct)
  • Primary filter
  • Glow rod
  • Bypass valve

    • How does the nozzle unit attach to the nozzle holder in a fuel injector?

  • By a nozzle cap nut (correct)
  • With screws and bolts
  • Through a sealing ring
  • With crimped edges

    • What type of fuel filters are located at the fuel inlet and outlet connections of the injectors?

    <p>Protective filters</p> Signup and view all the answers

    What is the capacity of the fuel tank mentioned in the content?

    <p>6000 liters</p> Signup and view all the answers

    What type of injector is described as having both electronic and mechanical options?

    <p>Both EUI and MUI</p> Signup and view all the answers

    What is the purpose of the sight glass in the fuel return system?

    <p>To show fuel levels</p> Signup and view all the answers

    How does the MUI differentiate its injector output?

    <p>Through adjusting the calibrating slide</p> Signup and view all the answers

    What is the micron rating for the secondary filter mentioned?

    <p>13 micron</p> Signup and view all the answers

    What is the designated flow rate of the gear pump as specified in the content?

    <p>7.5 gal/min</p> Signup and view all the answers

    What is the main purpose of a sediment filter in the fuel system?

    <p>To filter out larger droplets and abrasive matter</p> Signup and view all the answers

    What indicates that the primary fuel filter elements need renewal?

    <p>When the change filter zone reads approximately 30 psi</p> Signup and view all the answers

    What is the function of the relief valve in the engine mounted fuel filter assembly?

    <p>To return fuel to the tank when pressure exceeds 70 psi</p> Signup and view all the answers

    What occurs when the primary filters in the system become plugged?

    <p>The bypass valve opens and fuel bypasses the filters</p> Signup and view all the answers

    What is the primary role of the fuel injector in the combustion chamber?

    <p>To atomize the fuel into a fine spray</p> Signup and view all the answers

    How does the system manage excess fuel delivered by the fuel pump?

    <p>It cools and lubricates the injectors</p> Signup and view all the answers

    What mechanism allows fine water droplets in fuel to agglomerate?

    <p>The porous filter element</p> Signup and view all the answers

    What happens to the fuel flow when the injectors are restricted?

    <p>The relief valve opens to reroute the fuel</p> Signup and view all the answers

    Which component indicates the need to change the primary fuel filters?

    <p>Pressure differential indicator</p> Signup and view all the answers

    Why is fine wire gauze not used in the fuel filtering system?

    <p>It can block too easily</p> Signup and view all the answers

    What type of pump is primarily used in the fuel oil system of the GM locomotive?

    <p>Positive displacement gear pump</p> Signup and view all the answers

    Which characteristic distinguishes an internal gear pump from an external gear pump?

    <p>Improved suction and delivery</p> Signup and view all the answers

    What role does the crescent seal play in the fuel oil pump?

    <p>Separates inlet and outlet sections</p> Signup and view all the answers

    How is the motor-driven fuel pump powered during operation?

    <p>Power from the Auxiliary Generator</p> Signup and view all the answers

    Which component is responsible for mixing warm fuel with fuel from the pump?

    <p>AMOT mixing valve</p> Signup and view all the answers

    What is the main function of the primary fuel filter in the system?

    <p>Sediment filtering</p> Signup and view all the answers

    What is one advantage of using the internal gear pump over the external gear pump?

    <p>Smoother operation</p> Signup and view all the answers

    What happens to the fuel as it exits the pre-heater?

    <p>It flows to the AMOT mixing valve</p> Signup and view all the answers

    The flow arrangement in the fuel pre-heater is designed to maximize what?

    <p>Cooling effect</p> Signup and view all the answers

    What is used to drive the fuel pump during system priming?

    <p>Battery power</p> Signup and view all the answers

    What function does the nozzle cap nut serve in a fuel injector?

    <p>It secures the nozzle body to the nozzle holder.</p> Signup and view all the answers

    Which of the following statements about the adjustable calibrating slide on MUI injectors is true?

    <p>It is incorporated for adjusting injector output on a calibrating stand.</p> Signup and view all the answers

    What range of fuel back pressure is maintained by the relief valve in the fuel system?

    <p>15 PSI</p> Signup and view all the answers

    What type of fuel filter is located at the inlet of the injectors?

    <p>Strainer with a 600 micron rating</p> Signup and view all the answers

    What component is found adjacent to the rack on a Mechanical Unit Injector?

    <p>Calibrating slide</p> Signup and view all the answers

    Which part of the fuel injector is primarily responsible for preventing contaminants from entering the injector?

    <p>Filters at the fuel inlet and outlet</p> Signup and view all the answers

    What is the purpose of the sight glass in the return fuel system?

    <p>To determine the fuel condition visually</p> Signup and view all the answers

    What is the primary role of the strainer in the fuel system?

    <p>To filter out small particles before fuel enters the injector</p> Signup and view all the answers

    What aspect of the engine fuel system does the EFCOS component relate to?

    <p>Fuel supply regulation</p> Signup and view all the answers

    Which safety feature prevents backflow in the fuel system?

    <p>Bypass valve</p> Signup and view all the answers

    What pressure differential indicates that the primary fuel filter needs to be changed?

    <p>30 psi</p> Signup and view all the answers

    What occurs when the fuel injectors are supplied with restricted flow due to plugged filters?

    <p>A relief valve opens to bypass fuel to the tank</p> Signup and view all the answers

    How does the agglomerate flow mechanism help in filtering fuel?

    <p>It allows fine water droplets to combine into larger drops</p> Signup and view all the answers

    What is the purpose of the bypass valve in the primary fuel filter system?

    <p>To ensure fuel continues to flow when the filter is plugged</p> Signup and view all the answers

    What role does the sight glass play in the fuel return system?

    <p>It allows visual monitoring of returning fuel flow</p> Signup and view all the answers

    What mechanical action takes place when the primary fuel filter becomes increasingly blocked?

    <p>The gauge reading increases until it signals a change</p> Signup and view all the answers

    What is the function of the relief valve in the engine mounted fuel assembly?

    <p>To allow fuel to bypass injectors when pressure is too high</p> Signup and view all the answers

    What potential issue arises from using fine wire gauze as a filter in the fuel system?

    <p>It can easily become blocked due to its fine structure</p> Signup and view all the answers

    What happens to the excess fuel delivered by the fuel pump?

    <p>It cools and lubricates injector components</p> Signup and view all the answers

    What is the primary purpose of the primary fuel filter in the overall fuel system?

    <p>To remove larger droplets and abrasive materials from fuel oil</p> Signup and view all the answers

    What mechanism allows the internal gear pump to effectively transport fuel?

    <p>Trapped space between gear teeth</p> Signup and view all the answers

    What is a key advantage of an internal gear pump compared to an external gear pump?

    <p>Smoother operation and better suction</p> Signup and view all the answers

    Which of the following best describes the flow arrangement in the fuel pre-heater?

    <p>Counter flow to enhance thermal efficiency</p> Signup and view all the answers

    What role does the crescent seal play in the internal gear pump's operation?

    <p>To provide a positive seal and reduce leakage</p> Signup and view all the answers

    How is fuel directed after exiting the mixing valve?

    <p>Through the primary fuel filter for sediment removal</p> Signup and view all the answers

    What is a characteristic feature of the internal gear pump compared to the external gear pump?

    <p>Higher complexity in design and manufacturing</p> Signup and view all the answers

    Why is the motor driven fuel pump mounted on the equipment rack?

    <p>For easy access and maintenance</p> Signup and view all the answers

    What is the primary function of the battery during the operation of the fuel pump?

    <p>To provide energy during system priming</p> Signup and view all the answers

    What is the primary design consideration for the crescent seal in the pump?

    <p>To reduce internal leakage effectively</p> Signup and view all the answers

    What is the main purpose of the pre-heater in the fuel oil system?

    <p>To heat the fuel for better combustion</p> Signup and view all the answers

    What are the two main components of a fuel injector?

    <p>Nozzle unit and nozzle holder</p> Signup and view all the answers

    What is the purpose of the adjustable calibrating slide on a Mechanical Unit Injector (MUI)?

    <p>To adjust injector output</p> Signup and view all the answers

    What pressure does the relief valve maintain at the inlet to the fuel return sight glass?

    <p>15 PSI</p> Signup and view all the answers

    What component protects the working parts of the injectors?

    <p>The strainer</p> Signup and view all the answers

    What is the primary function of the nozzle cap nut in a fuel injector?

    <p>To secure the injector body</p> Signup and view all the answers

    What type of filters are used in the fuel system discussed?

    <p>Micron-rated filters</p> Signup and view all the answers

    What is the role of the secondary filter in the fuel system?

    <p>To filter out fine particles</p> Signup and view all the answers

    What is indicated by pressure differential concerning the primary fuel filter?

    <p>The need for replacement</p> Signup and view all the answers

    What happens to fuel delivered by the fuel pump when injectors are restricted?

    <p>Fuel pressure drops</p> Signup and view all the answers

    What component separates the inlet and outlet in a gear pump to reduce internal leakage?

    <p>Crescent seal</p> Signup and view all the answers

    During what phase is the motor-driven fuel pump powered by battery power?

    <p>During system priming</p> Signup and view all the answers

    What is the primary function of the pre-heater in the fuel oil system?

    <p>To increase the fuel temperature</p> Signup and view all the answers

    What type of filter is used as the primary fuel filter in the system?

    <p>Canister type filter</p> Signup and view all the answers

    How does the fuel exit the internal gear pump?

    <p>After the gear teeth come into mesh</p> Signup and view all the answers

    What is mixed at the AMOT mixing valve?

    <p>Warm fuel with fuel from the pump</p> Signup and view all the answers

    In the fuel pre-heater, how do the fluids flow to achieve maximum cooling?

    <p>In opposite directions</p> Signup and view all the answers

    What happens to the fuel after it exits the primary filter?

    <p>It flows to the mixing valve</p> Signup and view all the answers

    What indicates that the primary fuel filter needs to be changed?

    <p>When the indicator reaches the red change filter zone</p> Signup and view all the answers

    What happens when the primary filters become plugged?

    <p>The bypass valve allows fuel to bypass the filter</p> Signup and view all the answers

    What mechanism allows fine water droplets in fuel to combine into larger droplets?

    <p>Agglomerate flow</p> Signup and view all the answers

    What role does the indicator in the primary fuel filter play?

    <p>It signals when the filter should be changed</p> Signup and view all the answers

    How does the primary fuel filter contribute to engine performance?

    <p>By providing clean fuel to the fuel injectors</p> Signup and view all the answers

    What is a key feature of the fuel return system?

    <p>It returns unused fuel back to the tank</p> Signup and view all the answers

    What is the expected pressure differential reading that indicates a filter change is due?

    <p>30 psi</p> Signup and view all the answers

    What occurs to the fuel flow when the engine mounted fuel filter becomes plugged?

    <p>The relief valve opens to bypass fuel</p> Signup and view all the answers

    Study Notes

    Fuel Oil System of GM Locomotive

    • The fuel oil system starts by drawing fuel from a storage tank through a fuel suction strainer.
    • A motor-driven positive displacement gear type pump is used to draw the fuel.
    • Gear pumps are positive displacement pumps, frequently used in fuel systems needing pressures up to 3,600 PSI.
    • Fuel is drawn into the pump inlet, filling the space created by the gear teeth moving out of mesh.
    • Fuel then gets trapped between the gear teeth and transported to the outside of the pump.
    • The gear mesh forces fuel out through the outlet.

    Positive Displacement Pump

    • Gear pumps are a type of positive displacement pump.
    • These pumps are commonly used in systems with operating pressures up to 3,600 PSI.
    • Gear pumps are further categorized as external or internal gear pumps.

    External Gear Pump

    • Teeth of external gear pumps are positioned on the outside of the gears.
    • The teeth on one gear mesh with the teeth on the interior of a larger gear.
    • Pumping chambers are formed between the gear teeth.
    • A crescent seal separates the inlet and outlet.
    • The crescent seal is machined into the valve body where spacing between the teeth is largest.
    • This design produces a positive seal between inlet and outlet, minimizing internal leakage.

    Internal Gear Pump

    • The internal gear pump has features similar to the external gear pump.
    • Internal types commonly exhibit enhanced suction and delivery characteristics, resulting in smoother operation.
    • Manufacturing and maintenance of internal gear pumps are usually more complex and costly compared to external gear pumps.

    Fuel Oil Pump

    • The motor-driven fuel pump is mounted on the equipment rack.
    • The pump is an internal gear type, driven by the battery during system priming and by the auxiliary generator during regular operation.

    Pre-Heater

    • Some fuel is pumped through a pre-heater.
    • Some fuel is directed through an AMOT mixing valve.
    • Fuel warmed by the pre-heater moves to the AMOT valve where it combines with fuel from the pump.
    • The fuel pre-heater’s function is to heat the fuel oil. The process uses water to heat the oil.
    • A pre-heater uses a heat exchanger that heats fuel by passing it around a tube through which water flows. This design maximizes cooling efficiency by using the opposite directions for coolant and fuel flow.
    • The pre-heater warms the fuel to 35°C.

    Primary Filter

    • Fuel exiting the mixing valve travels through the primary fuel filter.
    • A canister-type primary fuel filter assembly is mounted on the equipment rack under the lube oil cooler assembly.
    • The primary filter is a simple sediment filter.
    • It is not made from fine wire gauze due to potential blockage.
    • The filter’s job is to remove larger water droplets and abrasive material from the fuel.
    • A bypass valve and gauge are connected across the primary filters to allow fuel to bypass if the primary filters become plugged. The gauge will indicate the pressure difference across the filter, with a range of approximately 20-30 psi indicating typical operation.

    Engine Mounted Fuel Filter Assembly

    • After passing through the primary fuel filter, fuel moves through engine-mounted fuel filters, increasing the level of filtration.
    • A relief valve is incorporated into the engine-mounted fuel assembly.
    • The engine-mounted fuel filter assembly has a relief valve to return fuel to the tank if the primary and/or engine mounted filters become clogged. A relief valve will open at a preset high pressure (70 psi).

    Main Filters

    • The main filters operate based on an agglomerate flow mechanism.
    • When fuel containing fine water droplets passes through the porous filter element, the droplets combine to form larger drops. This agglomeration increases the particles' ability for removal.

    Relief Valve

    • If engine-mounted fuel filter elements become clogged, fuel flow to the injectors is restricted.
    • To address this, a relief valve opens at a set high pressure (70 psi), allowing fuel to return to the tank, bypassing the fuel injectors.
    • This prevents fuel starvation or damage to the fuel injectors.

    Fuel Injector

    • Fuel injectors attach to the combustion chamber.
    • Fuel injectors atomize, or break up, fuel into a fine spray within the cylinder.
    • There are two main types of fuel injectors, Electronic Unit Injectors (EUI), and Mechanical Unit Injectors (MUI).
    • MUI’s feature an adjustable calibrating slide on the injector body's side.
    • Filters at the inlet and outlet connections protect the injector's working components.

    Fuel Back Pressure

    • A relief valve, located at the inlet to the fuel return sight glass, creates a fuel back pressure of 15 PSI.
    • This maintained back pressure ensures a reliable fuel supply for the injectors.
    • The return fuel sight glass shows the back pressure.

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    Fuel Oil System GM PDF

    Description

    This quiz covers the fundamental concepts of the fuel oil system utilized in GM locomotives, focusing on gear pumps as a type of positive displacement pump. You'll learn about the operation of these pumps and their classifications, including external gear pumps, as well as their role in fuel systems. Test your knowledge on pump mechanics and applications.

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