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30 Cards in this Set
- Front
- Back
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What is meant by the power stroke? |
The power stroke is the stroke of the piston produced by expanding gases and is the working stroke of the engine. |
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What is a cycle |
A series of events which are repeated in regular order to bring about the efficient operation of an engine. |
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How do the cylinders get their fuel oil for ignition to create the power? |
A By having the fuel oil sprayed into them B By pumps |
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What is meant by valve timing? |
The adjusting of the valves to open and close at the proper time for efficient operation of the engine. |
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What is meant by supercharging |
Increasing the amount of charging air in the working cylinder |
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What is the purpose of scavenging in the engine cylinder? |
To remove combustion products and to supply fresh air to the cylinder |
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What is the function of oil control rings? |
Controls the amount of oil on liner walls and scrapes off any sludge |
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Name one advantage and one disadvantage of fitting dry liners |
Advantage: Light construction Cheap No corrosion or erosion of external surfaces No water contamination of Sump Disadvantage: Difficult to remove It can distort on fitting No access to cooling passages for cleaning Poor heat transfer |
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Name 1 advantage and 1 disadvantage of fitting wet liners |
Advantage Easy removal with special tools Good access to cooling passages More efficient cooling through direct contact Disadvantage Heavy construction More expensive Leakage can occur past 'O" rings causing water contamination of the lub oil |
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What are 5 causes of internal cylinder wear? |
Friction Corrosion Ring flutter Abrasives Poor lubrication |
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What are 2 effects of too large a tappet clearance? |
Valves open late closes early Poor induction Poor scavenge Loss of power Loss of efficiency Black smoke overheating |
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What are 2 effect of too small a tappet dearance? |
Valves open early closes late Loss of compression Loss of power Loss of efficiency After burning in exhaust |
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Whilst checking No 3 cylinder prior to setting the tappets, the push rod seemed to be distorted. What would be the possible cause of this defect? |
Over-speed of the engine Incorrect valve clearance |
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You have lifted the tappet/rocker cover to set the tappets. Would you check all of the components on the cylinder head or just concentrate on the tappets? |
Check all components An obvious time to do a cursory check of all components exposed, even if they are not part of the job. |
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Give 2 reasons why crankshaft deflections should be checked |
Replacement of bearings Uneven wear of bearings Replacing engine mounts Re-coupling over-hung weights |
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What are the requirements for a crankcase explosion |
Flammable vapour within the explosion range A hot spot to produce ignition |
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What sources of hotspots can cause crankcase explosions? |
Piston blowby Perforated piston crown Incipient seizure of components Bad fitting of re-metalled bearings Mis-aligned engine and shafting Main bearing failure Distortion of engine seating |
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What are 3 lube oil tests carried out on board? |
Acidity Carbon Viscosity |
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What are the purposes of the fuel injection pump |
To boost fuel pressure sufficient to open the injectors Deliver equal quantity of fuel to each cylinder To inject fuel at precisely the right time To vary the amount of fuel delivered To control the engine speed and power |
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What are three main components of the fuel injection pump |
Plunger and barrel Delivery valve and seating Swash plate |
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What are three symptoms of fuel injector nozzle problems |
Knock in engine Engine overheating Loss of power Black smoke Increased fuel consumption |
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What is viscosity |
Body or thickness of a liquid, measured time taken to travel certain distance at a certain temperature |
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State two reasons for including additives to live oil |
Detergent- clean the lube oil Rust inhibitor Control temperature |
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State the meaning of flash point |
Temperature at which a liquid produces a flammable vapour and if ignition source available an explosion would occur |
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List four types of lubrication systems |
Open Closed Splash Direct Submerged Gravity |
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What is the importance of lube oil testing. What are you testing for? |
To identify early faults Carbon in oil Water (fresh or salt) contamination Dilution of oil Viscosity |
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Why is it necessary to carry out periodic performance tests? |
To check condition of the equipment To identify defect that may need attention To ascertain that the equipment is able to perform to full rated performance |
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What is the purpose of a vibration damper and where is it usually located? |
To absorb rotational vibration from the crankshaft, located on the non drive end of the crankshaft |
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Why are multi stage and sequential turbo-blowers used? |
Higher efficiencies of the plant Improved specific fuel usage Improved combustion to reduce toxic emissions Lower exhaust gas temperatures |
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How may fuel consumption be measured for performance trials? |
By snap tank Flow meters Dipping of tank |
