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26 Cards in this Set
- Front
- Back
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Which gas law does a combustion engine fall under |
Adiabatic - No heat flow takes place across the boundaries of the system during compression or expansion of the gas. |
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What are three classifications of marine engine application. |
Slow speed - 70-250rpm Medium speed - 250-1000rpm High speed - over 1000rpm |
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Draw the cross section of a slow speed 2 stroke. |
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Why is the cross head pin so big |
Larger surface area for better boundary lubrication. |
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What material are exhaust valves usually made out of |
Nimonic - nickel, molybdenum, chrome alloy |
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How is the timing chain lubricated |
Spray nozzle system of the main lubricating oil system |
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How do we measure crank shaft deflection |
Dial gauge between web, at four different point, with the conrod attached |
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Describe the three different methods of crankshaft assembly |
Mono-block - one piece. Fully built - journals and crank pins separate and shrink fitted together. Semi-built - Web and journals separate, journals are shrink fitted to the website. |
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What are the three scavenging flows, and which is the best and why. |
Uni-flow - Most air flow and change out of exhaust gases. Cross flow Loop flow |
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What do indicator diagrams/cards do |
Illustrate the pressure variations in the cylinder when the engine is operating. |
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What is valve overlap, and explain it |
Valve overlap is when both the exhaust valve and the scavenging ports are open at the same time, this is to allow for the exhaust gases to be effectively discharged from the cylinder, allowing fresh air in for combustion. |
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State 3 causes of early ignition |
Incorrect fuel cam position Fuel pump plunger set to high Higher cetane/better quality fuel |
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What are two methods of removing dirt deposits from the turbine side of a turbocharger |
Water washing Dry cleaning (walnut shell) |
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What is the purpose of an air cooler |
To increase the mass per unit volume of air. |
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What functions does lubricating oil perform |
Lubricates Cooling Sealing Cleaning Preserves Noise reduction Spark erosion |
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Describe how cylinder lubrication is achieved in a slow speed diesel engine |
Cross head type - oil is supplied external service tank. Which supplies oil to lubricating pumps for each cylinder. The lubricating pumps supply oil to the liner via quills, the pumps are timed to pump as the piston is in a downward stroke. |
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3 ways turbochargers are lubricated |
Engine oil Separate oil supply Sealed oil system |
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What is the function of a governor |
To maintain the speed of the engine from no load to full load. |
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Why turbocharging |
Increases volumetric efficiency |
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What are the causes of a crank case explosion |
Hot spot Fuel oil dilution - most common |
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Steps taken in the event of a crank case explosion |
- Reduce load - Stop engine - Open indicator clocks, start pre lube pumps, manual turning gear - Let cool down for at least 30min |
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List start interlocks |
3 start failure Start to long Star air press low RPM detector fail Engine tripped Engine not ready: governor not conected, start air |
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Two types of cam reversing |
Lost motion Hydraulic cam |
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Indications of a scaveng fire |
High scavenge temps, alarms, bad smell Turbo pulsing |
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Response to a scavenge fire |
Stop cylinder fuel supply Slow down engine Increase cylinder lubrication Avoid shouting down engine |
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What are 5 essential condions that must monitored under NSCV |
- engine lube oil press - engine jacket water cooling outlet temp - engine g/box lube oil press - charging rate of gen or state of batteries - rotational speed of shaft |
