Week 3 Prime Movers Flashcards
Prime movers
True or false The engine flywheel should be pinned and locked out before entering the crankcase.
True
Before performing any maintenance on a recently run engine, you must do what?
disconnect any electrical feed and close, lock, tag and purge all gas sources.
True or false When working in areas of high concentrations of hydrogen sulphide (H2S), you should always wear a personal alarm monitor.
True
The thermal efficiency of an engine is best described as the ability of the engine to what
change the energy in the fuel to usable heat energy and power.
The amount of air an engine is able to take into the cylinder compared to with the volume of the cylinder is called what
Volumetric efficiency
The description of compression ratio is best stated as
the cylinder volume plus the combustion chamber volume, divided by the combustion chamber volume.
The description of compression ratio is best stated as
the cylinder volume plus the combustion chamber volume, divided by the combustion chamber volume.
True or false Two stroke engines have running mates
False, only four store have running mates. This is because the two-stroke engine fires on all cylinders every Revolution ( 360° of crankshaft rotation).
How do you find the engine displacement?
Area of bore by the length of stroke by number of cylinders.
True or false When comparing a diesel engine to a gas engine the compression pressures and ratios are three times high or more .
False, it twice as much.
When air is compressed, what are the noticeable effects?
The temperature increases, as the volume becomes smaller.
When you are determining engine rotation using the SAE standard, you view the engine from?
the main power end of the engine
Which type of head design has the valves in the block?
L head engine
True or false Indicated horsepower is the power at the flywheel of the engine.
False, indicated horsepower is the theoretical power of an engine.
True or false A two-stroke engine completes one cycle in 720 ° of rotation.
False, it is completed in 360°.
True or false Potential energy is the energy resulting from the motion of an object.
False, this is kinetic energy.
True or false An undersquare engine is an engine with a larger stroke than bore.
True
Blowby is leakage past the rings.
True
Running mates are pistons that reach TDC at the same time.
True
What are the three requirements to make fuel combust?
Fuel, air, and ignition.
True or false The fuel must be atomized and mixed with air to be burned.
True
True or false At the end of the exhaust stroke, the intake and exhaust valves are open at the same time.
True
A two-stroke engine makes twice as much power as a four-stroke engine of the same capacity.
False, it is the opposite. This is because the effective power stroke is shorter.
True or false Integral engines require proper alignment with the driven equipment.
False, because they use the same crankshaft and block.
Spark-ignition engines have a much lower compression ratio than diesel engines.
True
The classification for an engine with a normal operating speed of 800 rpm is a low-speed engine.
False, An engine with a normal operating speed of 800 rpm would be classified as a medium-speed engine.
What is the function of the flywheel?
The flywheel stores energy and smoothes the power pulses from the pistons.
True or false The lighter the flywheel, the smoother the engine runs.
False, the heavier the smoother.
The linear and rotary motion are create how in the ICE?
Linear from the piston and rotary from the crankshaft. Connected by the connecting rod.
What is the purpose of the balancer?
To reduce crankshaft torsional vibration.
You should check the machined surfaces of the cylinder block for flatness using what two measuring tools?
straight edge and feeler gauge
What could misaligned main bearing bores cause?
excessive bearing wear or a broken crankshaft.
True or false An underslung crank has the main bearing caps at the bottom of the crank.
True
Which of the following should you not use to clean aluminum components?
A hot caustic soap tank
Identify two measuring tools that you use in order to check the main bearing bores on an engine block.
Inside mics and dial bore gauges.
True or false You can repair cylinder liners on large engines by hard chroming and grinding to size.
True
Why do you use alloy cast iron for engine block material?
The alloy cast iron is strong.
Why must the outside diameter of a dry liner fit the cylinder block bore correctly?
to allow heat transfer from the liner to the block material and to support the liner
True or false Wet type cylinder liners are in direct contact with the coolant.
True
What do leaking o-rings on a wet liner cause?
coolant to enter the crankcase.
When reconditioning a cylinder bore, you can use a de-glazing hone to do what?
Restore cylinder wall crosshatch
Identify four important checks that you must complete during a new cylinder liner installation.
Check cylinder bore for out-of-round, taper and cracks, Check all seal surfaces, Check liner counter bore, and Check liner protrusion height.
which is the most common fuel injection system?
The mechanical injection system is the most used.
true or false most gasoline engines do not use cylinder liners.
true
true or false gasoline engines have heavier pistons than diesel.
false, diesel have heavier pistons to help dissipate heat due to higher temperatures.
true or false on a Two-stroke diesel scavenging engine with exhaust ports the scavenging valve is open as the piston lowers from TDC?
false, this would remove all the higher pressure air that the piston builds.
true or false in a two stroke engine the camshaft travels at one half the speed of the crankshaft.
False, two stroke do not have camshafts. camshafts are found on four stroke to regulate intake and exhaust valves.
True or false An underslung crank has the main bearing caps at the bottom of the crank.
True
Four stroke six cylinder engines should have 60 ° between power strokes. A) true b) false 4.
False, they should have 120° degrees between power strokes.
Crankshafts should be stored by standing them on end, or on a level floor on V blocks for larger crankshafts.
True
What is the purpose of the crankshaft?
Change reciprocating motion into rotary motion.
Crankshaft journal fillets must be maintained to?
Prevent crankshaft breakage
What is mounted onto the flywheel to aid in starting purposes?
A ring gear
A harmonic balancer that has an interference fit should be removed using
A puller
Another name for friction bearings used in engines is:
Precision inserts
Focalized (spot) wear on a bearing is likely caused by:
Foreign material between the bearing shell and bearing bore.
When installing bearings, you should not lubricate:
The bearing backs
When removing main and / or connecting rod bearings, you should mark them for:
Reinstallation and future analysis.
What is plastigage?
Pliable plastic string
List the four main components of a piston and connecting rod assembly.
Connecting rod, piston, piston pin, and piston rings.
What is the purpose of a connecting rod?
It forms a link between the piston and the crankshaft that transmit the force of combustion.
True or false The connecting rod bearing clearance can be checked by the lift check method.
True
True or false Aluminum pistons are fitted tighter than cast iron pistons.
False, expands more
True or false Drilled holes in the piston’s oil ring groove drains oil back to the crankcase.
True
True or false Rings are installed with the dot, notch or number toward the crankshaft.
False, does Face the pressure
True or false Ring gaps should be lined up one above the other prior to piston installation.
False, they must be staggered to prevent leakage.
true or false Oil control rings depend only on their expanders to maintain contact with the cylinder walls.
True
the torque produced by an engine is dependent on the break mean effective pressure, BMEP, which is what?
the average pressure acting on the piston crown during the power stroke and on engine displacement.
A two stroke cycle gasoline engine: A) does not require intake and exhaust valves B) must have two cylinders C) produces half as much power as a four stroke cycle engine D) is of more complex construction than a four stroke cycle engine E) has two power strokes per crank revolution
A) does not require intake and exhaust valves
Using a compressed air starting motor is a typical method of starting a: A) small two stroke engine B) jet engine C) large stationary Diesel engine D) high performance engine E) natural gas engine
C) large stationary Diesel engine
Compression ignition engines: A) will compress air only on the compression stroke B) will compress air only on the power stroke C) need a carburetor to mix fuel with air D) always have suction and discharge valves E) require a spark timing device
A) will compress air only on the compression stroke
The two stroke gas engine finds application where: A) only low quality fuels are available B) maximum power with minimum size is required C) large power output is required D) high torque at low speed is required E) low speed is required
B) maximum power with minimum size is required
Overloading of an individual cylinder in a Diesel engine is indicated by: A) a high exhaust temperature B) a high lube oil temperature C) a low exhaust temperature D) excessive oxygen in the exhaust E) excessive blower discharge pressure
A) a high exhaust temperature
n a compression ignition engine, fuel is normally ignited by: A) high voltage spark igniters B) a magneto spark C) a glow plug D) hot compressed air E) combustor crossfire chambers
D) hot compressed air
A four stroke cycle engine: A) uses exhaust ports rather than valves B) requires four strokes to produce one power stroke C) has the intake valve open during the entire exhaust stroke D) has a lower weight than an equivalently sized two stroke cycle engine E) has four power strokes per crank revolution
B) requires four strokes to produce one power stroke
An example of an engine which gives high torque at low speeds would be that of a: A) chain saw B) two cycle snowmobile C) four stroke motocross motorcycle D) two cylinder lawnmower E) two cycle transit bus
C) four stroke motocross motorcycle
The process of vaporization of gasoline and mixing with air for use in a naturally aspirated internal combustion engine is known as: A) oxidation B) fuel injection C) carburetion D) combustion E) supercharging
C) carburetion
An engine which develops one power stroke with every other turn of the crankshaft is the: A) external combustion unit B) V type engine C) two stroke Diesel engine D) four stroke natural gas engine E) type which requires premixing lube oil and fuel
D) four stroke natural gas engine
Diesel engines require: A) fuel injectors B) a carburetor C) a distributor cap D) a magneto E) a spark plug in each cylinder
A) fuel injectors
In a compression engine the fuel is ignited by
The compressed air temperature
Diesel engine governing is accomplished by
Varying the fuel quantity
Internal combustion engines used to drive gas compression machinery and which burn natural gas operate on the _______ stroke cycle
Two or four
How is fuel in a gasoline engine delivered?
An injector A carburetor
What is a fuels resistance to premature detonation called?
Octane rating
Four-stroke cycle valves are operated by
Cams
The purpose of a spark plug is
To ignite the air fuel mixture in a gasoline engine
An engine which develops one power stroke with every other turn of the crankshaft is the
Four stroke natural gas engine
Four cycle engine lubrication may be accomplished by
Pumping oil under pressure
An example of a gasoline engine which gives high torque at low speeds would be A. chainsaw B. two cycle snowmobile C. four stroke motor cross motorcycle D. two cycle lawnmower E. two cycle transit bus
c
A major difficulty encountered with a two-stroke cycle engine is
Exhausting the spent gasses from the cylinder
When does the exhaust valve open on a four cycle engine
The end of the power stroke
A four stroke ignition engine in theory has ______ the power of a two stroke engine
Half
When does the spark plug ignite the air/fuel mixture in a four stroke engine
Near the end of the compression stroke
How many ports does a simple two stroke spark ignition engine have?
2
Define cylinder scavenging
is the process of replacing the exhaust gas in a cylinder with the fresh air/fuel mixture (or fresh air, in the case of direct-injection engines) for the next cycle.
true or false Compression engines will compress air only on the compression stroke
true
An injection nozzle is used to _________ the fuel in a Diesel engine
Atomize
In larger two stroke Diesel engines how is scavenging air provided
With superchargers
The injection pump of a Diesel engine is driven by the
Camshaft
Ignition in a Diesel engine is started by
Compression in the cylinder
What is a diesels engines camshaft driven by?
The crankshaft
How high might the compression ratio of a Diesel engine be
15:1 to 23:1 typically
What is the purpose of a pushrods in a typical four stroke Diesel engine?
To operate a rocker arm
How might the frame of a Diesel engine be constructed?
Cast or welded
When using compressed air to each cylinder for starting purposes, the pressure is approximately
2100 Kpa or 304.5792 psi
Reduction in sealing qualities between the piston rings and cylinder wall by the lube oil may be a result of
High cooling water temperature
Large internal combustion engines achieve cooling by use of
Water jackets
In the case of large industrial Diesel engines which is started using compressed air direct to the cylinders, when is the air actually admitted to the cylinders
On the power stroke
In which ways might a Diesel engine be started
Hand cranking Air starter motor Electric starter Compressed air delivered to cylinders glow plug
What must be done before starting a large Diesel engine?
Prime the fuel injector pump
What problems could a leaking fuel injector cause in a Diesel engine?
Abnormally high exhaust temperatures Smoky exhaust
Internal combustion changes chemical energy in fuel to
Useful heat
Gasoline is
Liquid hydrocarbons enhanced with benzene or Iso-octanes
The process of vaporization is know as
Carburetion
Most modern engines now use
Direct fuel injection
Heavy oil fuel is important in what type of combustion engine
High compression engines
What are the for steps of a four struck ignition cycle
Intake Compression Power exhaust
How is the crankcase lubricated
Pumped under pressure or splashed
Two advantages of Four cycle engines
Good fuel economy and good control at all speeds
Two stroke ignition cycle have no
Valves or camshaft
How is two stroke engine lubricated
My mixing special lubrication with gasoline in the tank
In the carburetor the gasoline is
Vaporized
Two cycle engines are best for
Max power and min size. Best at high engine speeds
In a Diesel engines the fuel is injected at
High pressure directly into the engines cylinder in liquid form (finely atomized)
In Diesel engines ignition takes place with out the aid of a
Spark
What is the ratio of the volume of atmospheric air drawn into the cylinder on the intake stroke to the cylinder displacement.
Volumetric efficiency
Compression ratio is figured out how?
Compression ratio: displacement plus clearance volume / clearance.
List the four stages of a Diesel engine
Suction Compression Power Exhaust
In a two stroke Diesel engine removal of exhaust is done by
Scavenging
What are the most common methods of air induction
Supercharges and turbochargers
Diesel engines use what type of ignition
Compression
Diesel engines have no
Carburetor
What does a carburetor do
Mix air and fuel
What are the moving parts in a Diesel engine
Piston Connecting rods Crank pins Crankshaft Main bearings
gasoline engine compression ratio
8∶1 and 12∶1
The fuel for a Diesel engine is Mechanically atomized by high pressure
high pressure
What is the Primary system on an ICE?
Compression system (mechanical/valve)
what are the operating systems on an ICE?
- Air intake System 2. Fuel System 3. Exhaust system
what are the auxiliary systems on an ICE?
- Ignition system
- Lubrication system
- Cooling System
- Starting System
Governor system
Charging System
What are the three categories of internal combustion engine systems?
fuel source, stroke, ignition.
Identify the components of the primary
or compression system
Piston
Piston Rings- Compression rings, Oil rings
Head gaskets
cylinder head
cylinder block
Intake valves
Exhaust valves
Valve springs
Spring retainers
Valve guides
push rods
camshafts
list different Battery-type ignition systems
* Breaker point-type battery system -an ignition switch begins the process
* Ignition coil - converts low battery voltage to high voltage
*Distributor - sends the high voltage current to the correct spark plug
* Condenser – function as a capacitor which stores electrical energy
Breaker points - a switch to initiate the spark
CDI - replaces points with an electronic pick-up
Distributor cam -controls the opening and closing of the breaker points or electronic pickup
name two types of spark ignition starters
spark plug
* Magneto-type ignition systems – use
magnets and coils to generate electrical spark
name four benefits of a oil sump
* Windage *
Cooling
* NVH Noise * noise vibration harmonics
Strengthen block
name some parts of the lub system
* Oil filter - removes dirt particles from oil
* Pressure regulator - maintains the operating pressure of the system
*Sump – a reservoir for the engine oil
*Oil pump - circulates oil through the engine
* Windage Tray / Baffles / Dry sump / Splash *
Full filter / Bypass / Calibrated loss
* Pre-lube / After-lube * Small 2 stroke – Premix / oil
the Purpose of the Lubrication System is to maintain proper operation by reducing friction and cooling internal engine components name four ways it does this
*Splash Lubrication
* Mist Lubrication
* Pressure Lubrication
* Full Pressure Lubrication
what are the two different cooling systems
liquid and air
name points of the liquid cooling system
* Radiator - a heat transfer device
Water pump - forces the coolant to flow through the system
* Thermostat - a flow control valve
* Water Jacket- a series of interconnected
cavities cast into the engine block & cylinder
head for circulation of coolant.
Combustion is usually lost in one of three places:
*Piston / rings / cylinder fit
*Head gasket
* Valves
The numbering on engine cylinders usually starts where?
Opposite to the flywheel
Thermal efficiency shows how well an engine converts the energy in the fuel into mechanical energy. This is usually what percentage?
25% to 35%
Shunt field DC motors can be made to have adjustable speed through
field control or armature control
In a shunt field DC motor torque does what and why
torque remains constant because the current through the field remains the same
In a shunt field DC motor the speed changes how much from no load to full load?
from no load to full load, the speed’ not suitable for adjustable-speed of motor does not change mUaR- loads. this results In good speed regulation.
How much amperage is required to energize a shunt field DC motor?
Little amperage.
Why in a shunt field DC motor is motor’s ability to cool Itself Is reduced when running at a slower speed?
Fan speed
Shunt field DC motors are not suitable for
Adjustable-speed loads.
True or false series connected field DC motors are suited to light starting duty where less severe loads are expected
False, they are suited to heavier duties, and severe loads.
Series connected field motor requires what to limit speed?
Loads
True or false Series connected field motor are good for high torque, traction, and lifting.
True
Compound Field motors have what type of starting torque?
High
True or false Compound Field motors can withstand no overloads
False, they can withstand heavy overloads.
True or false single phase squirrel cage rotor, or know as induction motors, DC motor are the most efficient?
False, induction motors are three phase.
True or false on a squirrel cage induction motor the rotor must always turn slower than the synchronous speed or there will be zero Induced current and no torque.
True
True or false Wound rotor ,induction, AC motors are good for heavy to no loads, and variable speeds. But the sound rotor builds temperature and creates resistance.
True
Which induction motor has the rotor windings connected through slip rings to external resistance.
Wound or slip ring rotor AC motors.
Which AC motors use single phase?
No, AC is there phase.
