4BE3 U1 C1 Review
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Questions and Answers

What is the primary definition of friction between two surfaces?

  • Corrosion control between the surfaces
  • Lubrication of the surfaces
  • Resistance to motion or attempted motion (correct)
  • Reduction of wear on the surfaces

    • What can microscopic analysis of smooth surfaces reveal?

  • Lubricant properties
  • Absolutely smooth surfaces
  • Corrosion effects
  • Countless surface irregularities (correct)

    • What is the primary function of lubrication in relation to surface irregularities?

  • To increase friction between surfaces
  • To separate surfaces with interlocking surface irregularities (correct)
  • To control corrosion between surfaces
  • To create surface irregularities

    • Which of the following is NOT a purpose of lubricants?

    <p>Surface smoothing</p> Signup and view all the answers

    Why do surfaces cling or weld together when they rub against each other?

    <p>Due to the interlocking of surface irregularities</p> Signup and view all the answers

    What are the two most important purposes of lubricants?

    <p>Friction reduction and wear reduction</p> Signup and view all the answers

    What is the primary purpose of the thickening agent in semi-solid lubricants?

    <p>To increase the consistency of the lubricant</p> Signup and view all the answers

    Which type of grease is suitable for use in high-temperature applications?

    <p>Lithium base greases</p> Signup and view all the answers

    What is a characteristic of calcium base greases?

    <p>They are insoluble in water</p> Signup and view all the answers

    What is the advantage of using grease lubrication over liquid lubrication?

    <p>It provides a more permanent protective coating</p> Signup and view all the answers

    Which type of grease is suitable for use in wet conditions?

    <p>Calcium base greases</p> Signup and view all the answers

    What is the primary application of specialty greases?

    <p>Heavily loaded machinery</p> Signup and view all the answers

    Which type of lubricant is divided into three general classes?

    <p>Liquid lubricants</p> Signup and view all the answers

    What is the characteristic of aluminum base greases that makes them unsuitable for high-speed applications?

    <p>They have excessive internal friction</p> Signup and view all the answers

    What is the advantage of using grease-lubricated bearings?

    <p>They produce cost savings</p> Signup and view all the answers

    What is a characteristic of mixed base greases?

    <p>They are water-resistant to some degree</p> Signup and view all the answers

    What is the primary function of a lubricant in reducing wear?

    <p>To separate the surfaces and prevent high spots from coming into contact</p> Signup and view all the answers

    What is the result of a continuous wearing process on surfaces?

    <p>Large pieces of material are torn away, resulting in rougher surfaces</p> Signup and view all the answers

    What is the purpose of chemical compounds added to lubricants?

    <p>To prevent the formation of acids due to oxidation of the oil</p> Signup and view all the answers

    How do lubricants reduce the production of heat in bearings?

    <p>By reducing the friction and converting it into heat energy</p> Signup and view all the answers

    What is the primary function of a lubricant in shock absorption?

    <p>To provide a cushion to absorb shock</p> Signup and view all the answers

    What is the main characteristic of solid lubricants?

    <p>They are suitable for use with heavy loads, extreme temperatures, or both</p> Signup and view all the answers

    What is the purpose of a corrosion barrier film formed by a lubricant?

    <p>To prevent acid attack on metal surfaces</p> Signup and view all the answers

    What is the primary function of lubricants in sealing?

    <p>To provide sealing between pistons and cylinder walls</p> Signup and view all the answers

    What is the purpose of circulating large quantities of lubricant to bearings?

    <p>To absorb and carry away heat from the bearing surfaces</p> Signup and view all the answers

    What are the three general classes of lubricants?

    <p>Solids, Semi-solids, Liquids</p> Signup and view all the answers

    What is the characteristic of fixed oils?

    <p>They are non-volatile</p> Signup and view all the answers

    What is the primary function of synthetic oils in lubrication?

    <p>To provide resistance to sludge formation and oxidation</p> Signup and view all the answers

    What is the measure of the resistance of a liquid to internal deformation or shear?

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

    What happens to the viscosity of oil when its temperature increases?

    <p>It decreases</p> Signup and view all the answers

    What is the unit of measurement for the viscosity of oil using a Saybolt viscometer?

    <p>Saybolt Seconds Universal (SSU)</p> Signup and view all the answers

    What is the purpose of the viscosity index of an oil?

    <p>To measure the change in viscosity of oil with a temperature change</p> Signup and view all the answers

    What is the significance of the pour point of oil?

    <p>It determines the lowest temperature at which oil will flow</p> Signup and view all the answers

    What is the purpose of the flash point of an oil?

    <p>To determine the temperature at which oil will ignite</p> Signup and view all the answers

    What is the significance of the neutralization number of oil?

    <p>It indicates the acidity of oil</p> Signup and view all the answers

    What is the purpose of additives in lubricating oil?

    <p>To improve the desirable characteristics of oil</p> Signup and view all the answers

    What is the purpose of pour point depressants in lubricating oils?

    <p>To lower the pour point of the oil and allow it to remain fluid at low temperatures</p> Signup and view all the answers

    What type of oil is often used in steam turbines to reduce the risk of ignition?

    <p>Synthetic fire-resistant turbine oil</p> Signup and view all the answers

    What is a critical property of air compressor cylinder oils?

    <p>Low carbon residue</p> Signup and view all the answers

    Why are corrosion inhibitors added to internal combustion engine oils?

    <p>To prevent corrosion of engine components</p> Signup and view all the answers

    What is the purpose of viscosity index improvers in lubricating oils?

    <p>To reduce the change in viscosity with temperature</p> Signup and view all the answers

    What is the primary function of lubricating oils in a turbine circulating system?

    <p>To serve as a sealing medium and a lubricant</p> Signup and view all the answers

    What type of oil is preferred for enclosed gears, such as turbine reduction gears?

    <p>Low viscosity oil</p> Signup and view all the answers

    What is the purpose of anti-oxidant additives in internal combustion engine oils?

    <p>To reduce deposit formation</p> Signup and view all the answers

    What is the significance of the floc point in refrigeration compressor oils?

    <p>It determines the temperature at which paraffin wax settles out</p> Signup and view all the answers

    What is the purpose of detergent dispersants in refrigeration compressor oils?

    <p>To deal with deposits that may be formed</p> Signup and view all the answers

    What is the primary reason for the interlocking of surface irregularities?

    <p>To cause the surfaces to cling or weld together</p> Signup and view all the answers

    What is the main purpose of lubrication in relation to surface irregularities?

    <p>To separate surfaces with interlocking irregularities</p> Signup and view all the answers

    What is the result of the interlocking of surface irregularities?

    <p>A resistance to relative motion between surfaces</p> Signup and view all the answers

    What is the primary purpose of lubrication in relation to friction?

    <p>To reduce friction between surfaces</p> Signup and view all the answers

    What is the primary function of lubricants in wear reduction?

    <p>To reduce the wear of surfaces</p> Signup and view all the answers

    What is the primary reason for using lubricants in corrosion control?

    <p>To prevent corrosion of surfaces</p> Signup and view all the answers

    What is the main advantage of using a lubricant to separate two moving surfaces?

    <p>It reduces the friction by preventing the high spots of the surfaces from coming into contact.</p> Signup and view all the answers

    What is the primary reason why grease is less likely to drip or splash from bearings compared to liquid lubricants?

    <p>The thickening agent in grease provides a more permanent protective coating</p> Signup and view all the answers

    What is the purpose of chemical compounds added to lubricants?

    <p>To prevent the formation of acids due to oxidation of the oil.</p> Signup and view all the answers

    What is the primary advantage of using mixed base greases over calcium base greases?

    <p>Mixed base greases are more water-resistant</p> Signup and view all the answers

    What is the characteristic of solid lubricants that makes them suitable for use with heavy loads or extreme temperatures?

    <p>They can withstand heavy loads or extreme temperatures.</p> Signup and view all the answers

    What is the primary characteristic of sodium base greases that makes them suitable for high-speed ball and roller bearings?

    <p>They are more adhesive and cohesive</p> Signup and view all the answers

    What is the primary function of lubricants in relation to surface irregularities?

    <p>To reduce the wear on the surfaces by preventing the high spots from coming into contact.</p> Signup and view all the answers

    What is the primary disadvantage of using aluminum base greases in high-speed applications?

    <p>They have excessive internal friction</p> Signup and view all the answers

    What is the purpose of lubricants in reducing wear?

    <p>To prevent the high spots of the surfaces from coming into contact.</p> Signup and view all the answers

    What is the primary purpose of using specialty greases in heavily loaded machinery?

    <p>To reduce friction</p> Signup and view all the answers

    What is the primary function of lubricants in sealing?

    <p>To provide a barrier between surfaces to prevent leakage.</p> Signup and view all the answers

    What is the purpose of lubricants in temperature control?

    <p>To reduce the production of heat by reducing friction.</p> Signup and view all the answers

    What is the primary characteristic of barium and lithium base greases that makes them suitable for high-temperature service?

    <p>They have a higher thermal stability</p> Signup and view all the answers

    What is the primary reason why grease is more convenient to handle and replenish compared to liquid lubricants?

    <p>Grease requires less equipment</p> Signup and view all the answers

    What is the primary function of lubricants in shock absorption?

    <p>To provide a cushion to absorb shock.</p> Signup and view all the answers

    What is the main advantage of using lubricants in corrosive environments?

    <p>They form a corrosion barrier film to prevent corrosion.</p> Signup and view all the answers

    What is the primary characteristic of mineral oils that makes them the most commonly used class of lubricants?

    <p>They are produced from crude petroleum</p> Signup and view all the answers

    What is the primary function of lubricants in reducing friction?

    <p>To provide a barrier between surfaces to prevent contact.</p> Signup and view all the answers

    What is the primary reason why calcium base greases are not suitable for use in high-temperature applications?

    <p>They lose their moisture and separate above 70°C</p> Signup and view all the answers

    What is the primary advantage of using grease-lubricated bearings over liquid lubricants?

    <p>They require less attention</p> Signup and view all the answers

    What is the primary characteristic of lubricating oils with a high viscosity index?

    <p>Their viscosity changes little with temperature changes</p> Signup and view all the answers

    What is the primary function of carbon residue testing in lubricating oils?

    <p>To determine the amount of carbon an oil will form when subjected to high temperatures</p> Signup and view all the answers

    What is the primary effect of temperature on the viscosity of lubricating oils?

    <p>As temperature increases, viscosity decreases</p> Signup and view all the answers

    What is the primary purpose of detergent-dispersant additives in lubricating oils?

    <p>To keep deposit-forming substances in suspension in the oil</p> Signup and view all the answers

    What is the primary characteristic of fixed oils?

    <p>They are non-volatile</p> Signup and view all the answers

    What is the primary function of the flash point of a lubricating oil?

    <p>To indicate the temperature at which a fire or explosion may occur</p> Signup and view all the answers

    What is the primary effect of a low pour point on the lubricating properties of an oil?

    <p>It allows the oil to flow at lower temperatures</p> Signup and view all the answers

    What is the primary function of anti-oxidant additives in lubricating oils?

    <p>To decrease the amount of oxygen that combines with the oil</p> Signup and view all the answers

    What is the primary characteristic of synthetic oils?

    <p>They demonstrate resistance to sludge formation and oxidation</p> Signup and view all the answers

    What is the primary function of the viscosity of a lubricating oil?

    <p>To indicate the ability of the oil to flow</p> Signup and view all the answers

    What is the primary function of lubricant in a turbine circulating system?

    <p>All of the above</p> Signup and view all the answers

    What is the consequence of having a too low viscosity in air compressor cylinder oils?

    <p>All of the above</p> Signup and view all the answers

    What is the primary purpose of anti-oxidant additives in internal combustion engine oils?

    <p>To prevent the oil from evaporating and thickening</p> Signup and view all the answers

    What is the significance of the pour point in refrigeration compressor oils?

    <p>It determines the temperature at which the oil will not congeal</p> Signup and view all the answers

    What is the purpose of detergent dispersants in refrigeration compressor oils?

    <p>To deal with deposits formed</p> Signup and view all the answers

    What is the primary characteristic of internal combustion engine oils?

    <p>High viscosity index</p> Signup and view all the answers

    What is the purpose of corrosion inhibitors in turbine oils?

    <p>To form a protective film on metal surfaces</p> Signup and view all the answers

    What is the primary characteristic of air compressor cylinder oils?

    <p>Viscosity within a suitable range at operating temperatures</p> Signup and view all the answers

    What is the primary purpose of viscosity index improvers in refrigeration compressor oils?

    <p>To improve the viscosity index of the oil</p> Signup and view all the answers

    What is the primary characteristic of gear lubricating oils used in enclosed gears?

    <p>Low viscosity</p> Signup and view all the answers

    Study Notes

    Friction and Surface Interaction

    • Friction refers to the resistance between two surfaces in contact, opposing their relative motion.
    • Microscopic analysis of smooth surfaces reveals that even flat surfaces have irregularities, affecting friction.
    • Surfaces cling or weld when rubbed against each other due to the interlocking of microscopic surface irregularities.

    Lubrication Functions

    • Primary functions of lubrication include reducing wear and serving as a barrier to corrosion.
    • Lubricants help minimize the effects of surface irregularities by filling gaps and reducing frictional contact.
    • The thickening agent in semi-solid lubricants provides structure and maintains viscosity.
    • Lubrication also aids in shock absorption by cushioning impacts between surfaces.

    Types of Grease

    • High-temperature applications benefit from using barium and lithium base greases.
    • Calcium base greases are characterized by their water resistance but are unsuitable for high temperatures.
    • Mixed base greases offer advantages over calcium base greases in various applications.
    • Specialty greases are designed for specific high-load or extreme temperature conditions.

    Viscosity and Performance

    • Viscosity measures the resistance of a liquid to shear or internal deformation.
    • Viscosity of oil decreases with an increase in temperature.
    • Saybolt viscometer measures oil viscosity in seconds.
    • The viscosity index indicates the stability of a lubricant's viscosity with temperature changes.

    Additives and Stability

    • Additives in lubricating oils enhance properties such as oxidation resistance, wear protection, and temperature control.
    • Pour point depressants improve flow in low temperatures, while anti-oxidant additives prolong oil life in engines.
    • Detergent-dispersants keep contaminants suspended, preventing sludge formation in lubricants.

    Impact of Temperature

    • The flash point indicates the temperature at which vapors can ignite, important for safety in lubrication applications.
    • Low pour points are beneficial for maintaining lubricating properties in cold environments.
    • Hydrogenation can improve the stability and performance of synthetic oils compared to mineral oils.

    Characteristics of Oils and Greases

    • Mineral oils are the most commonly used lubricants due to their affordability and effectiveness.
    • Internal combustion engine oils have characteristics that facilitate engine performance and longevity.
    • Air compressor cylinder oils require specific properties like resistance to foaming and thermal stability.

    Benefits of Lubrication

    • Grease lubrication is advantageous as it reduces the risk of leakage and can withstand extreme conditions better than liquid lubricants.
    • Grease’s structure allows for reduced drip or splash, making it ideal for certain applications.
    • Lubrication enhances the longevity of machinery by minimizing wear and creating a smoother operational environment.

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    Description

    Learn about friction as a force that opposes motion between two surfaces. This quiz explores the concept of friction, its causes, and how surface irregularities affect motion.

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