Stationary Engines Flashcards
List main engine components
cylinder head and valves, block or frame, cylinders, pistons and rings, connecting rods, crankshaft, camshaft, lifters and rocker arms, flywheel, bearings, balancer, timing gears and auxiliary drives
Define an engine
a mechanical device that converts the chemical energy stored in a fuel to heat then to mechanical energy
Define power
the rate at which work is being done
What is the power required to overcome engine frictional and pumping losses?
friction horsepower
What is Indicated Horsepower?
The theoretical power of an engine.
What is Brake Horsepower and how is it calculated?
BHP is the actual power measured at the end of the crankshaft, it’s calculated as:
Brake HP = Indicated HP - Friction HP
Which engine would have a longer stroke length than bore diameter? What type of engine would normally have this characteristic?
an undersquare engine, diesel engines
What are the characteristics of an oversquare engine?
larger bore diameter than stroke length
What is the thermal efficiency for most engines?
25-40%
On a HP-torque curve what point of the curve indicates the approximate RPM for maximum volumetric efficiency?
the high point
What is volumetric efficiency?
the ratio of the volume of atmospheric air drawn into the cylinder on the intake stroke to the cylinder stroke
What is the name of the leakage of burned and unburned gases that gets past the compression rings into the crankcase?
blowby
What are the 4 strokes in one cycle of a 4-stroke engine?
intake, compression, power, exhaust
When does ignition take place on an SI (spark ignition) engine?
as the piston reaches a few degrees BTDC (before top dead centre)
How many crankshaft rotations does it take to complete a cycle on a 4-stroke engine?
2 revolutions (720 deg)
Where is engine rotation determined from?
by viewing the engine from the flywheel end
What is the main advantage to an integral engine?
it does not require coupling
What engine type has the most bearing area per cylinder?
the in-line arrangement
What are the 3 types of valve arrangements?
overhead valve (I head), multi-valve, and flat head (L head)
What are two possible camshaft positions?
overhead cams (OHC), and cam in the block (pushrod engine, most common)
Which is the most efficient valve arrangement?
overhead valve (I head)
What do naturally aspirated engines use to get air into the cylinders?
atmospheric pressure
Which type of engine requires some type of artificial means of pumping air into the cylinder?
2-stroke engines
What should be done to the engine flywheel before entering the crankcase?
it should be pinned and locked out
What is the crankshaft type that’s found in an engine with a one-piece block?
an underslung crankshaft
When checking for coolant leaks on an engine block with a pressure-test, what is the maximum PSI you should use?
45 PSI
What should the maximum deviation of the main bearing bores be?
no more than half the maximum allowable main bearing clearance (new condition)
What are some methods of checking main bearing bore alignment?
piano wire, laser, optical methods, deflection gauge (if crankshaft is in place)
Where is the highest wear area in a cylinder?
near the top of the liner due to high temperatures, pressures, and minimum lubrication
What are 3 methods used to treat cylinder liners to reduce the rate of wear?
induction hardening, hard chrome, nitriding
What are 3 types of cylinder liners?
dry liners, wet liners, air-cooled liners
When do you measure and record liners for wear?
While they are in the cylinder block.
What can you use to remove the ring that forms on the upper part of a cylinder under 6” in diameter?
a ridge reamer
What does deglazing restore inside the cylinder?
The crosshatch pattern on the cylinder wall.
What should you not use when cleaning the cylinder after deglazing?
solvents
What two measuring tools would you use when checking the machined surfaces of the cylinder block for flatness?
straight edge, feeler gauge
What would you not use to clean aluminium?
caustics
What is opposite of the rod throws on a crankshaft, and used to balance the rotating mass?
counterweights
What is used to stabilize speed fluctuations and store energy during power pulses to carry the engine to the next stroke?
flywheel
What are tangs or dowels used for with shell-type engine bearings?
to locate (and also hold with the dowel) the bearing half in the block
What is the purpose of bearing spread?
To keep the bearing from falling out during assembly.
What is the most accurate method of checking bearing clearance?
measurement
What is the most accurate method of tightening fasteners?
bolt stretch (elongation)
Which has a larger diameter on a piston, the ring land or the skirt?
the skirt
What type of piston has 2 pieces?
crosshead type (trunk-type is one piece)
Which piston ring is held against cylinder with spring pressure?
oil ring
On a 4-stroke engine, what is the speed of the camshaft in relation to the speed of the crankshaft?
camshaft speed is 1/2 crankshaft speed
What is the purpose of the camshaft lifter (valve lifter)?
to transfer motion to the pushrod
What component is the mechanical link between the pushrod and the valve?
the rocker arm
Where are valves primarily cooled from? Where does other cooling come from?
Primarily through heat transfer to the valve seat and guide (from the face and stem), intake valves receive additional cooling from intake air.
What could insufficient valve clearance cause?
burnt valves, poor engine performance
Which valve (intake/exhaust) is made of higher quality material and why?
Exhaust valves are because of the higher temps and corrosive gases they are exposed to.
What does the octane rating of a fuel refer to?
its ability to resist ignition due to compression (the higher the octane number, the more the fuel can resist self-ignition)
What is to avg mixture of air to fuel (by weight) for gas engines?
from 14-16 parts of air to 1 part of fuel
What determines how much of the air fuel mix enters the engine in a carburetor?
the throttle valve
Which is the low voltage circuit of an ignition system, the primary or secondary circuit? The high voltage circuit?
the primary circuit is low voltage, secondary is high voltage
Which ignition system creates its own power supply and distributes it to the coil?
the magneto ignition system
Between gasoline, LPG, natural gas or diesel, which has the higher BTU value?
diesel
What number indicates the ability of a fuel to ignite?
cetane number
What is a cetane number used for?
To rate the ignition characteristics of diesel fuel.
What components are in an induction system?
Pre-cleaner, air cleaner, intake manifold, may have a method of artificial respiration such as a turbo, blower, or a piston type air pump
What’s a waste gate? Where is it located?
A component the is used to control the boost on a turbo, located between the turbine and the exhaust manifold.
What’s the most commonly used coolant, and what’s a safer alternative to this coolant?
Ethylene Glycol based is the most common coolant, Propylene Glycol based is a safer alternative coolant.
What device could you use to test the strength of an antifreeze solution?
a hydrometer or a refractometer
What are the functions a lubricant serves in an engine lubrication system?
reduces friction, cools, seals, cleans and flushes, absorbs thrust
What are the types of oil pumps used in engine lube systems?
positive displacement rotary pumps such as external gear pumps (most common), vane, internal gear, and gerotor
Which oil filtration system filters all the oil after the oil pump before it reaches the bearings? How would the oil reach the bearings on a cold start up or when the filter is plugged?
The Full-Flow Filtration system, a bypass valve
What is the main function of an engine cooling system?
To regulate the engine temperature.
What is the most common type of thermostat?
wax pellet
What are the 3 methods of lubrication?
splash, splash and pressure, full pressure
What are the purposes of the pre and post lube pumps?
The pre-lube pump gets oil to critical parts of the engine before its turned over, the post-lube pump runs after the engine shuts down to cool down the engine and components, lube the bearings in the turbo as it winds down.
What would happen to the oil pressure if the relief valve was stuck open?
the pressure would be low
How big should the foundation for an engine (entire assembly) be in relation to the engine itself?
2.5 times the mass of the complete engine
What type of anchor bolt should be avoided when fastening an engine to the foundation?
J bolts
What are the 3 basic requirements for an engine to run?
air, fuel, ignition
What is the main purpose of an engine control system?
To monitor/control the engine, and shut down the engine in case of a critical alarm.
