Introduction to Reciprocating Engines - Unit 1
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Introduction to Reciprocating Engines - Unit 1

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Questions and Answers

What is the purpose of a safety circlet installed on some valve stems?

  • To reduce oil consumption
  • To improve valve spring action
  • To prevent the head from falling into the combustion chamber (correct)
  • To enhance engine performance

    • How can valve spring surge be eliminated?

  • By using a single valve spring
  • By using valve springs of the same coil diameter
  • By reducing the number of springs used
  • By using two or more valve springs with different coil diameters and pitches (correct)

    • What can occur if valves are ground to a feather edge?

  • Increased valve longevity
  • Improved combustion efficiency
  • Preignition and frequent repairs needed (correct)
  • Reduced oil consumption

    • What does a contour or radius gauge measure in relation to valves?

    <p>The stretch of the valves</p> Signup and view all the answers

    What is the relationship between piston displacement and cylinder dimensions?

    <p>Piston displacement equals cylinder area multiplied by stroke length</p> Signup and view all the answers

    What is the defining characteristic of a cam ground piston?

    <p>It expands to maintain a nearly round shape during operation</p> Signup and view all the answers

    Where is piston velocity at its maximum in the piston's cycle?

    <p>90° after top dead center and after bottom dead center</p> Signup and view all the answers

    Which type of piston rings can be used in chrome plated cylinders?

    <p>Cast iron rings</p> Signup and view all the answers

    What happens during the intake stroke in a four stroke cycle?

    <p>The fuel-air charge is drawn into the cylinder as the piston moves downward.</p> Signup and view all the answers

    What indicates the end of the power stroke in a four stroke engine?

    <p>Combustion is complete just after top dead center.</p> Signup and view all the answers

    When should ignition typically occur during the compression stroke?

    <p>20° to 30° before top dead center.</p> Signup and view all the answers

    What is the primary function of the exhaust stroke?

    <p>To expel exhaust gases from the cylinder.</p> Signup and view all the answers

    What could occur if the intake valve opens too early?

    <p>Hot combustion gases may cause a backfire.</p> Signup and view all the answers

    What remains open briefly during the transition from the power stroke to the intake stroke?

    <p>Only the exhaust valve.</p> Signup and view all the answers

    Where does the piston start its movement during the compression stroke?

    <p>At the bottom dead center.</p> Signup and view all the answers

    What occurs after the combustion during the power stroke?

    <p>The exhaust valves begin to open.</p> Signup and view all the answers

    What is valve overlap defined as?

    <p>The number of degrees of crankshaft rotation when both valves are off their seats.</p> Signup and view all the answers

    How does proper valve timing affect engine performance?

    <p>It enhances volumetric efficiency and lowers cylinder temperatures.</p> Signup and view all the answers

    What happens if hot valve clearance is set on a cold engine?

    <p>Excessive valve clearance will occur once the engine heats up.</p> Signup and view all the answers

    What effect does excessive valve clearance have on engine power?

    <p>Reduces the total opening duration of the valves.</p> Signup and view all the answers

    What could occur if valve clearance is inadequate?

    <p>Exhaust valves may not seat well, potentially leading to burning.</p> Signup and view all the answers

    What is the function of hydraulic valve lifters?

    <p>They maintain zero clearance using oil pressure.</p> Signup and view all the answers

    What is a key advantage of metallic-sodium filled exhaust valves?

    <p>They help to carry heat away from the valve head.</p> Signup and view all the answers

    What must be ensured when adjusting valves on an engine with a floating cam ring?

    <p>Cam bearing clearance should be properly accounted for.</p> Signup and view all the answers

    What is the effect of a higher compression ratio on engine performance?

    <p>It generally increases power.</p> Signup and view all the answers

    Which factors limit the maximum compression ratio in an engine?

    <p>Fuel detonation characteristics and engine design limitations.</p> Signup and view all the answers

    What does volumetric efficiency measure in an engine?

    <p>The actual mass of fuel-air mixture compared to the theoretical capacity of the cylinder.</p> Signup and view all the answers

    What is a potential result of improper valve timing in an engine?

    <p>Decreased mass of fuel-air entering the cylinder.</p> Signup and view all the answers

    Where does the most significant wear occur on a cylinder wall?

    <p>At the top of the cylinder where heat is greatest.</p> Signup and view all the answers

    What is the function of nitriding in relation to engine cylinders?

    <p>It hardens cylinders to enhance wear resistance.</p> Signup and view all the answers

    What characteristic defines choked or taper-ground cylinders?

    <p>They are smaller at the top where they screw into the cylinder head.</p> Signup and view all the answers

    What is one of the best indicators of combustion chamber problems?

    <p>The condition of the spark plug.</p> Signup and view all the answers

    Study Notes

    Introduction to Reciprocating Engines - Study Unit 1

    • This study unit outlines key concepts for the FAA knowledge test regarding reciprocating engines
    • The remaining topics are covered in Study Unit 2
    • Extraneous material (topics or regulations not directly tested) are omitted
    • This course is designed to expedite passing the FAA knowledge test

    The Four Stroke Cycle

    • The four-stroke cycle involves four piston movements: intake, compression, power, and exhaust

    • Intake: Fuel-air mixture drawn in as the piston moves down, with intake valve open

    • Compression: Piston moves up, compressing the mixture, exhaust and intake valves closed

    • Ignition (Power): Ignition occurs before top dead center (20-30° before TDC) creating power stroke

    • The power stroke has hot gases driving the piston down

    • Exhaust: Piston moves up, driving exhaust gases out through the open exhaust valve. Intake valve opens as the piston nears the end of exhaust stroke, to maximize the fuel-air mixture

    • Intake valve closes shortly after bottom dead center on the compression stroke

    • Exhaust valve opens before bottom dead center on the power stroke

    • Exhaust valve remains open briefly allowing exhaust gas to escape on the intake stroke, due to inertia

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    Related Documents

    Reciprocating Engines Study Guide Ch. 1 PDF

    Description

    This quiz covers the fundamental concepts of reciprocating engines necessary for the FAA knowledge test. Focus is on the four-stroke cycle, detailing the processes of intake, compression, ignition, and exhaust. Prepare with targeted content to enhance your understanding and pass the FAA test efficiently.

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