Marine Diesel Engineering Exam - SQA Small Vessel Second Engineer 060-01
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Questions and Answers

Why should the air outlet from the turbocharger be cooled before entering the diesel engine cylinder?

To increase the density of the air and improve combustion efficiency

Why does the charge air cooler have fins attached to its tubes?

To increase the heat transfer rate

State possible reasons why the charge air cooler's performance may be reduced.

Possible reasons include fouling, corrosion, or leakage

Identify the component parts A-E in the section of timing chain shown in the figure below.

<p>Component A: Sprocket, Component B: Chain guide, Component C: Timing chain, Component D: Tensioner, Component E: Crankshaft gear</p> Signup and view all the answers

Explain the reasons why chains may elongate or slacken in service and the areas that may wear.

<p>Chains may elongate due to wear between the pins and bushings, while slackening can occur due to tensioner wear. Areas that may wear include the pins, bushings, and rollers.</p> Signup and view all the answers

Describe a procedure for manually testing the set points on diesel generator HT cooling water, high temperature alarm, and shut down.

<p>The procedure involves checking the set points, simulating high temperatures, and verifying the alarm and shut down responses.</p> Signup and view all the answers

How can the pump sketched in part (a) vary the end of delivery?

<p>The pump can vary the end of delivery by adjusting the timing of the fuel injection process.</p> Signup and view all the answers

What is the meaning of the term 'microbial contamination' in relation to diesel engine fuel?

<p>Microbial contamination refers to the presence of microorganisms, such as bacteria, fungi, or algae, in the diesel fuel.</p> Signup and view all the answers

What problems may a diesel engine encounter if the fuel is contaminated with microbes?

<p>If the fuel is contaminated with microbes, the engine may encounter problems such as clogged fuel filters, fuel line blockages, and corrosion of fuel system components.</p> Signup and view all the answers

How can microbial contamination in diesel fuel be avoided?

<p>Microbial contamination can be avoided by using clean fuel storage tanks, regularly cleaning the fuel system, and adding biocides or fuel stabilizers to the fuel.</p> Signup and view all the answers

What actions should be taken if microbial contamination in diesel fuel is severe?

<p>If microbial contamination is severe, the fuel system should be thoroughly cleaned, the fuel filters replaced, and the fuel tank drained and refilled with clean fuel.</p> Signup and view all the answers

What are FOUR functions of lubricating oil in a diesel engine?

<p>The four functions of lubricating oil in a diesel engine are: 1) Reducing friction and wear, 2) Cooling engine components, 3) Cleaning and removing contaminants, and 4) Sealing engine components.</p> Signup and view all the answers

Explain the terms 'hydrostatic lubrication' and 'boundary lubrication' in the context of lubricating oil.

<p>(i) Hydrostatic lubrication refers to a lubrication regime where a thick film of oil completely separates the moving surfaces, minimizing direct contact and friction. (ii) Boundary lubrication occurs when the oil film is too thin to fully separate the surfaces, and some direct contact between the surfaces takes place.</p> Signup and view all the answers

What is one advantage and one disadvantage of using grease as a lubricant in a plain bearing?

<p>Advantage: Grease can provide better sealing and prevent the ingress of contaminants into the bearing. Disadvantage: Grease may not dissipate heat as effectively as liquid lubricants, leading to increased operating temperatures.</p> Signup and view all the answers

Sketch the assembly of a plate-type heat exchanger, label the main components, and indicate the direction of flow.

<p>The main components of a plate-type heat exchanger are the corrugated plates, the gaskets or seals, and the inlet and outlet ports. The flow of the two fluids should be indicated as counter-current or parallel, depending on the design.</p> Signup and view all the answers

Describe the possible causes and remedies for low lubricating oil pressure in a diesel engine.

<p>Possible causes: 1) Worn or damaged oil pump, 2) Clogged oil filters, 3) Leaks in the oil system. Remedies: 1) Replace the oil pump, 2) Clean or replace the oil filters, 3) Inspect and repair any oil leaks.</p> Signup and view all the answers

What are three advantages and three disadvantages of using a wet clutch in a friction clutch system?

<p>Advantages: 1) Better heat dissipation, 2) Smoother engagement, 3) Longer service life. Disadvantages: 1) More complex design, 2) Increased maintenance requirements, 3) Potential for fluid leaks.</p> Signup and view all the answers

What is one advantage and one disadvantage of using multiple plates in a friction clutch system?

<p>Advantage: Multiple plates can increase the overall surface area for friction, allowing for greater torque transmission. Disadvantage: The use of multiple plates can increase the overall size and complexity of the clutch system.</p> Signup and view all the answers

Study Notes

Diesel Engine Fuel

  • Microbial contamination refers to the presence of microorganisms in diesel engine fuel.
  • Microbial contamination can cause problems such as:
    • Fuel filter blockages
    • Fuel pump failure
    • Injector fouling
  • Microbial contamination can be avoided by:
    • Using fuel additives that inhibit microbial growth
    • Storing fuel in clean, dry tanks
    • Regularly testing fuel for microbiological activity

Lubricating Oil

  • Functions of lubricating oil:
    • Reduces friction between moving parts
    • Cools engine components
    • Prevents corrosion
    • Carries away contaminants
  • Hydrostatic lubrication: a type of lubrication where a thin film of lubricant is maintained between moving parts.
  • Boundary lubrication: a type of lubrication where the lubricant forms a thin film between moving parts, but does not completely separate them.

Plate Type Heat Exchangers

  • Assembly:
    • Plates are corrugated to increase heat transfer area
    • Plates and seals are typically made of stainless steel or titanium
  • Purpose of corrugated plates: to increase heat transfer area
  • Purpose of tell-tales: to indicate fluid flow

Diesel Engine Faults

  • Low lubricating oil pressure:
    • Causes: worn engine bearings, low oil viscosity, oil pump failure
    • Remedies: check oil level, replace engine bearings, replace oil pump
  • Overheating:
    • Causes: coolant leaks, radiator blockages, thermostat failure
    • Remedies: check coolant level, clean radiator, replace thermostat
  • Unstable speed:
    • Causes: faulty fuel injectors, governor malfunction, turbolag
    • Remedies: clean or replace fuel injectors, adjust or replace governor, check turbine performance

Friction Clutches

  • Advantages of wet clutches:
    • Can dissipate heat quickly
    • Can handle high torque loads
    • Are resistant to wear
  • Disadvantages of wet clutches:
    • Require regular maintenance
    • Can be noisy
    • Require a high-pressure oil system
  • Advantage of multiple plates: increased friction surface area
  • Disadvantages of multiple plates:
    • Increased weight
    • Increased complexity
    • Increased cost

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Prepare for the Small Vessel Second Engineer certification exam in Marine Diesel Engineering administered by the Scottish Qualifications Authority on behalf of the Maritime and Coastguard Agency. The exam is scheduled for Friday, 20 January 2023, from 1400 to 1600 hrs. Candidates are advised to review the notes for guidance provided in the examination paper inserts.

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