Stationary Engines Flashcards
1
Q
What should be done before working on larger engines?
A
If it has a barring device, be sure it is locked out. Pin, lock and tag the flywheel
2
Q
What is an engine?
A
A mechanical device that converts the chemical energy stored in a fuel to heat, and then mechanical energy.
3
Q
What is the formula for work?
A
Work=force X distance
4
Q
What is power?
A
Power is the rate at which work is being done
5
Q
What are the different types of power?
A
Horsepower
Friction horsepower- frictional losses
Indicated horsepower- no losses, theoretical
Brake hp- indicated-frictional
6
Q
What does a vacuum gauge read at atmospheric pressure?
A
29.92 inches Mercury
7
Q
What is a square engine?
A
When the stroke and bore are both the same dimension
8
Q
What is an undersquare engine?
A
When the bore is smaller than the stroke. The majority of industrial engines are undersquare
9
Q
How is piston displacement determined?
A
Area of bore X length of stroke
10
Q
What is engine displacement?
A
The volume swept by all the Pistons
11
Q
What is clearance volume?
A
The volume remains when piston is at TDC
12
Q
What is blowby?
A
It is the leakage of burned and unburned gasses past the compression rings into the crankcase
13
Q
What are the four strokes in one cycle of a four stroke?
A
Intake - suck
Compression - squeeze
Power - bang
Exhaust - blow
14
Q
How do you tell if an engine runs cw or ccw?
A
View the engine from main power takeoff or flywheel end. If it rotates to the right its a CW left its CCW
15
Q
What are the six common cylinder and crankshaft arrangements?
A
In line, v type, integral, opposed piston, horizontally opposed, radial
16
Q
What are the two types of ignition methods?
A
Compression ignition (CI) - diesels Spark ignition (SI)
17
Q
What is the engine block?
A
It is the foundation of the engine. It maintains all moving parts in proper relative position to each other, and encloses the crankshaft and camshaft
18
Q
What are the drilled passages in the block for?
A
To carry lubricating fluid to the bearing areas
19
Q
What other things are in the block?
A
Water jackets, coolant passages, and cooling deflectors to carry the coolant to and from the various parts of the engine
20
Q
Describe a one piece block
A
It is the most common type of block. The main bearing caps under the crankshaft therefore it is called underslung crankshaft
21
Q
Describe a multi piece block?
A
They are common in larger low and medium speed engines with bores approximately 10 inches and larger. These blocks usually have overslung crankshafts where the main bearing caps are on top of the crankshaft. this is because the crankshaft mounts in the bed plate
22
Q
What should not be used for cleaning aluminum engine components?
A
Caustics, as they attack and corrode aluminum.
23
Q
When cleaning a head, for servicing, what should be done with oil galleries?
A
When first taking apart cover any oil galleries with suitable plugs. Spray down the block with solvent and flush out all the oil galleries and channels. Then dry off the solvent with compressed air to make sure there are no particles in the lube galleries
24
Q
How do you check the block for cracks?
A
Visually, dye penetrant, mag particle. To check for coolant leaks, fit the block with sealing plates, fill with water, and pressure test, never more than 45 PSI
25
What are some other things to check when doing a block inspection?
Check the cylinder block deck surface in several locations for flatness using a straight edge and feeler gauges. Clean and check the condition of the liner counterbore. Check the bottom liner bore where the O-ring on the liner seal may have some pitting due to cavitation. Check the top and bottom liner counterbores
26
If the block deck is resurfaced what must be done?
Because the piston to head clearance may change the spec should be checked.
27
What is the maximum deviation of the main bearing bores?
No more than half the maximum allowable main bearing clearance, in new condition.
28
How is main bearing bore alignment checked on larger engines?
If crankshaft is removed, a piano wire or laser or optical.
| If crankshaft is still installed, it's checked using a deflection gauge placed between the webs
29
What must also be checked on the bore?
It needs to be checked for size, taper and out of round using an inside micrometer or dial bore gauge.
30
What is line boring?
It is a procedure that uses a boring bar to machine the main bearing bores.
31
What is the cylinders function?
It is a cylindrical tube that serves as the chamber to confine expanding gases while they are pushing down on the piston. If they are not straight and smooth there will be leakage past the piston and rings that translate into a loss of energy
32
Large industrial engines have what type of cylinders for long service life?
Removable liners. They can be dry, wet, or air cooled. They are held in the block by the cylinder head or by studs passing through the liner and cylinder head
33
Where is the highest wear area in the cylinder?
Near the top due to high temperatures, pressures, and minimum lubrication.
34
What are some methods to treat the inside of the cylinder liner to reduce the rate of wear?
Induction hardening, hard chroming, nitriding
35
When should measurements be taken on liners, and why?
When the liners are out of the block they are easily distorted and measurements can be inaccurate
36
How can a liner with minor cavitation be salvaged?
Reinstall it 90° from its original position
37
What can cause excessive or premature liner wear?
Dust or fine particles that come through the air filter, or leaks in the intake system
38
What can be used to remove a small ridge at the top of the cylinder?
A hand operated Ridge reamer can be used in cylinders under 6 inches in diameter. If not removed new rings will hit against the ridge and break the piston rings or the piston ring lands
39
How is deglazing done, and what is the purpose
A ball deglazer or flexible hone is used. It removes polished and Glazed surfaces and produces a crosshatch pattern in the cylinder which retains oil for lubrication of the rings.
40
What is the proper crosshatch pattern?
40° to 60°. Honing with the drill speed of 300 to 400 RPM while making one complete vertical strokes per second produces the correct crosshatch angle
41
How is the cylinder cleaned after honing or deglazing?
Use a bristle brush and hot soapy water to clean the cylinder. To check cleanliness wipe with the lightly oiled lint free white cloth, and when the cloth shows no evidence of residue the bores are clean finally apply a light film of oil to prevent corrosion
42
What should be measured when reinstalling a wet liner?
The liner counterbore should be measured for depth and flatness using a depth micrometer
43
What is the purpose of the crankshaft?
It converts the downward linear motion of the piston to useable rotary motion. It also ties all the Pistons together to create one large timed rotary force. It also provides a mounting surface for the flywheel and harmonic balancer
44
What are crankshafts made from?
Forged alloy steel which is either flame or induction hardened.
45
What are the main parts of the crankshaft?
Main bearing journals, connecting rod journals or throws, webs, counterweights
46
What are the counterweights for?
They are used to balance the rotating mass opposite of the Rod throws.
47
How are the power pulses figured out in two stroke and four stroke engines?
On two-stroke engines it is the number of cylinders divided by 360° and four stroke are at intervals of 720° divided by the number of cylinders
48
Where is the thrust face normally located?
Near the flywheel end of the crankshaft
49
How are crankshafts best stored?
They're best stored standing the crank on its end. For large longer cranks store them laying flat but supported by v blocks on the main bearings
50
What is the purpose of the flywheel?
It is used to stabilize speed fluctuations, and store energy during power pulses to carry the engine to the next stroke. When doing this it has a balancing affect on the engine and reduces vibration.
51
What other things may be on the flywheel?
It may have a ring gear mounted for starting purposes. They also typically have timing marks stamped on the outer circumference of the flywheel to aid in checking and adjusting the timing
52
How is the flywheel used in lockout?
It can be pinned and blocked to prevent rotation
53
What is another name for a vibration dampener
A balancer or harmonic balancer
54
Where are vibration dampeners located?
They are on the opposite end of the flywheel and act like a torsional shock absorber
55
What are the different types of vibration dampeners?
Rubber mounted, viscous type, spring type.
56
What type of vibration dampeners are we repairable?
Only the spring type are repairable.
57
What is the purpose of the plain bearings
They support axial or radial loads. They provide an easily replaceable part that reduces the possibility of damage to the more expensive parts
58
What is another name for plain bearings?
Journal bearings
59
Explain journal bearing construction
Most of them have a steel backing with a layer or several layers of material that is compatible with the shaft and operating conditions. They may be layered with tin babbitt Copper lead or silver. In larger engines have solid aluminum or solid brass and bronze
60
What is fatigue strength
The ability of the bearing to withstand shock loads without flaking or cracking
61
What is embeddability?
The ability of the bearing to absorb small particles of dirt preventing damage to the shaft
62
What is conformability
The ability to mould itself to the imperfections of the crank journal
63
What are shell type bearings?
They are two-piece bearings which allows for easy removal and replacement. Some engines use tangs or dowels to hold them in place
64
What is bearing spread
When the bearing half is wider than the bore that is going to be installed. This gives it a tight fit in the bearing So the bearing does not fall out while being assembled
65
What is bearing crush
When the bearing inserts slightly protrude from the bearing. The purpose of this is for a tight fit which allows for better transfer
66
What are the different ways to measure bearing clearance?
Measurement, plastic gauge, lead wire, bearing lift checks
67
What is the most accurate way of checking bearing clearance
Measurement. But it is also the most time-consuming.
68
What is the fastest way to check bearing clearance?
Bearing lift check. But it is also the least accurate. Excessive force must not be put on the crank as it can give false readings and the crankcase can be damaged
69
What are the number one and number two reasons for bearing failure?
Number one is lack of lubrication, number two is lubricant contamination
70
What does it mean if there is more wear on one or more pairs of the bearings compared to the others
There is likely a problem with the alignment of the main bearing bores or the crankshaft. You should check the alignment and crankshaft runout
71
What are main bearing clearances usually?
.001-.003, however consult manufacturers specs
72
What should be done after all bearing caps are torqued?
Make sure the crankshaft rotate freely before you instal the Pistons connecting rods and connecting rod bearings
73
What is the connecting rod?
It forms the link that transmits the force of combustion from the piston to the crankshaft.
74
How are connecting rods constructed?
Like an I-beam. Most also have an oil passage drilled through the length of the rod to lubricate the piston pin, and cool the piston
75
What are the two types of cuts on the connecting rods?
Straight cut- used in smaller engines
| Bias cut- typical in larger engines. Bias cut can be pulled through the cylinder without taking the piston off
76
How are connecting rod caps organized?
They are match marked to keep them in the same position, and the bearing halves in alignment.
77
How is rod cap alignment accomplished?
Rod bolts which have a close fit, dowels, tongue and groove, serrated(sawtooth)
78
What is the most accurate method of rod bolt torquing?
Bolt stretch (elongation)
79
What are the basic parts of the piston?
Piston head, ring grooves,ring lands (smaller tan the skirt), oil drain holes, piston pins, skirt.
80
What are the different types of Pistons?
Trunk type - one piece piston
| Crosshead type- two piece. The skirt is separated from the top part, and it's all held together with the piston pin
81
What is a disadvantage of using aluminum Pistons?
It expands at 2X the rate of cast iron so the Pistons have to fit looser so the fit is correct at running temperatures.
82
How is the piston cooled and lubricated
Spray oil from the nozzle that is directed at the underside of the piston is the most common method on high-speed engines. Some oil also comes through the connecting rod
83
What are the three types of piston pins to connecting rod arrangements
Full floating pins -held with snap rings
locked to rod pins - turn in the piston only
locked on piston pins- held in piston with the rod turning on the pin
84
What is important to remember when servicing piston and pins
Make sure the oil drain back holes are cleaned.
Check dimensions and clearances
Check for cracks in the crown
85
What is the purpose of the compression rings?
They provide a dynamic seal between the piston and cylinder wall, prevent combustion pressured from entering the crankcase.
The oil control rings prevent lubricating oil from entering the combustion chamber and cool the piston by transferring heat to the cylinder walls
Cool the piston by transferring heat to the cylinder wall
86
How are the compression rings activated?
They have some initial tension to hold the ring against the cylinder, but they are activated by gas pressure from compression and combustion gases which forces the ring outward and down to seal
87
How is the oil ring activated?
Only by spring pressure
88
What can happen if there is too little side clearance between the ring and the ring land?
It can cause ring seizure and too much clearance can cause ring breakage and excess oil consumption
89
Before installation what else should you check with the rings in the piston?
Check to see how far the rings received into the ring groove. If they don't recede below the land, they are the wrong rings
90
What should you never use in the chrome faced liner?
Chrome rings it will seize almost instantly
91
Where should the lettering or dots on the ring face?
They should always face up
92
When installing piston into the cylinder what are the two ways to do this?
The rings must be compressed. This is done with the piston ring compressor, or using a tapered entrance sleeve
93
Why should Rod bolt protectors be used on the connecting rod?
To protect the cylinder wall and journal from scratching when sliding the connecting rod in place
94
What is a camshaft?
A lobed shaft. It controls the opening and closing of the intake and exhaust valves. The camshaft me also be used for fuel injection gas admission or air start
95
What is the speed of the camshaft on a four stroke engine
It is half the crankshaft speed. To achieve this a camshaft gear is made with twice as many teeth as the crankshaft gear. Two-stroke engines rarely have a camshaft
96
What does valve overlap aid in?
Scavenge efficiency
97
Why should lifters be put back where they came from?
Because they develop wear patterns
98
What are the three styles of lifters?
Hinged roller, roller, mushroom.
99
What is the job of the lifter?
To transfer motion from the camshaft to the pushrod
100
Why is the camshaft timing so important?
It determines the engines firing order and positions the camshaft for correct valve timing
101
What is the pushrod for?
It serves as a link between the lifter in the rocker arm in a camshaft in block engine
102
What is a rocker arm?
It is the mechanical link between the pushrod and the valve changing the upward motion of the lifter and pushrod into a downward motion of the valve
103
What is the function of the cylinder head
Seals the top of the cylinder, creates part of the combustion chamber, contains valves and ports, incorporates passages for coolant and oil, houses the intake and exhaust manifolds
104
What are most cylinder heads made of?
Most stationary engine heads are made of cast iron. Aluminum is widely used in automotive. Engines can use one head per cylinder, or one head for several
105
Which is constructed stronger, intake or exhaust valves?
The exhaust valve is usually made of a better material, due to higher temperatures, and corrosive gasses
106
How are valves cooled?
They are primarily cooled from heat transfer to the valve seat, and guide. Intake valves are additionally cooled from the incoming air charge. Approx 75% between the valve face, and valve seat , and last 25% from the valve stem to valve guide
107
What is the purpose of a valve rotator?
To help break carbon deposits on the valve seat, and promote even wear
108
What is the purpose of the valve guides?
To support and align the valve to keep it square with the valve seat
109
What do the valve seals do?
They control the lubrication of the valve guide and stem. If valve seals are worn oil migrates to the combustion chamber and you will see blue exhaust smoke, and increased oil consumption
110
What are some reasons for valve failure?
Distorted valve seats, carbon deposits on valve, insufficient valve clearance-valve held slightly open, doesn't seat or cool properly, engine running too hot, very large clearances can cause the head to break off from slapping closed too hard
111
If the head is to reconditioned what should be repaired first?
The valve guides, because the valve seats are ground using the valve guides as a pilot hole
112
How can a valve seat be removed?
Use a specific puller, use a special heeled chisel, weld a bead on the ID to shrink it.
113
Where should you start your tightening sequence in a cylinder head?
Start at the center and work outward. It should be done in several steps
114
Why are valve clearance adjustments needed?
To provide clearance for component expansion with engine temperature, compensate for wear in the valve operating mechanism
115
When should valves be adjusted?
When they are closed. If the piston is at TDC both exhaust and intake will be closed on compression stroke
116
Which of the fuels has the highest heat value?
Diesel
117
What is one BTU
The amount of heat required to heat 1 pound of water by 1°F
118
What is octane rating?
It is the ability of the fuel to resist ignition due to compression. The higher the number the more it has the ability to resist ignition due to compression
119
What is cetane rating?
The ability of a fuel to ignite easily under compression. The lower the number the harder it is to ignite under compression
120
Why is the spark introduced before top dead center?
Because of the short delay between the spark and full combustion. Full combustion should take place just slightly after top dead centre by a few degrees
121
What is pre ignition?
It means combustion takes place before there's a spark from the ignition system. It is caused by hotspots in the combustion chamber.
122
What causes the hotspots that causes preignition?
Spark plugs of the wrong range, glowing carbon deposits, the sharp edges in the combustion chambers that do not cool well
123
What is the results from Preignition ?
Mini sonic booms making the cylinder walls vibrate. There's excess pressure and heat as well
124
What is detonation?
It occurs after ignition, then a second ignition starts on the opposite side from heat and compression
125
What can cause detonation?
Low octane fuel's, lean mixtures, overheating, timing set too early.
126
What is stoichiometric combustion?
It is chemically ideal combustion
127
What must be done with gasoline fuel before it enters the engine cylinder?
It must be metered, atomized, and mixed with air before it enters the engine cylinder
128
What is the average mixture for gasoline by weight?
14-16:1 air:fuel
9000:1 by volume
129
What are the four basic parts of the carburetor fuel delivery systems
Carburetor, fuel pump, fuel tank, fuel filter
130
What is the throttle valves (butterfly) purpose?
It is the speed control mechanism for the engine. It controls the amount of air and fuel that enters the cylinder
131
Describe the choke in a carburetor
It is located before the Venturi, and closes off the air to get a richer fuel air mixture for starting
132
What is an ECM
Electronic control module. It is the computer that gathers information from the sensors and determines the amount of fuel to be delivered by the fuel injector
133
What opens the injectors in the fuel injected system?
They are electrically opened and closed by the computer
134
What does an oxygen sensor do
Indicates the oxygen content in the exhaust manifold with the sensor is warmed up.
135
What are the two types of fuel injection systems?
Pulse fuel and continuous fuel injection
136
What should the system have isolate the fuel from the natural gas fuel system?
Manual shut off valve
137
What is used in natural gas systems to filter the gas stream?
A gas scrubber. This is a vessel I can have one or several compartments. The fuel gas is sent through the scrubber where most of the particles of sand, rust, slag, water, or condensate are removed from the gas
138
What is the air fuel ratio for natural gas systems?
15.5:1 to 17:1
139
What must happen in order for the carburetor to work in a natural gas systems
There must always be a pressure differential between the air inlet pressure in the fuel inlet pressure at the carburetor. This means that the gas always has the higher pressure
140
What is the throttle valve attached to in the natural gas carburetor?
It is attached to the carburetor and controlled by the governor through linkage to control the amount of air fuel that enters the cylinders
141
When is the power of mixture adjustment screw adjusted on the natural gas carburetor
It is used to change the gas flow and is set with the engine operating at full load
142
Why is the linkage set up the way it is on the natural gas carburetors?
It is set so that is very small movement of the governor does not cause a large initial movement of the throttle and it's most sensitive position. This arrangement ensures that the governor does not overcorrect for engine load and speed
143
On the v style engines with dual plane manifolds why do the two banks need to be set to the same pressure?
If not done one side of the engine constantly overloads.
144
Where is the air and fuel in mixed in a natural gas fuel injection system?
They are not premixed before but instead are mixed in the engine cylinder
145
Why does propane leaks present severe fire and explosion hazard?
Because it is heavier than air, leaks accumulate in low lying areas, rather than dissipating into the atmosphere
146
Why can propane tanks only be filled to no more than 80% of its capacity
Because LPG expands very rapidly with temperature increases. The remaining 20% is to allow for expansion
147
What is the purpose of the converter/regulator also known as a vaporizer
The purpose of this component is to reduce the high pressure liquid propane to a low-pressure vapour
148
What are the two types of propane carburetors
Air valve carburetors and spray bar carburetors. Both are controlled by the throttle linkage either from the governor or a manual setting
149
What causes the characteristic diesel knock in a diesel engine?
The rapid and uncontrolled combustion followed by a controlled burn of the fuel
150
How is the diesel fuel injected in the cylinder?
Is injected into the combustion chamber. The fuel must be injected at the precise time and under high-pressure in order to penetrate, advise, and mix the fuel in the compressed air
151
Why is the cranking speed important on cold start up of diesel engines
The speed allows for less time for the heat to be absorbed by the cylinder and cylinder head therefore more heat is available to aid in the initiation of combustion
152
What are the main components of a diesel fuel system?
Fuel tank, fuel tank strainer, fuel transfer pump, primary fuel filter, secondary fuel filter, injection pump, injectors, fuel lines
153
What are the two types of control on fuel injection pumps or systems
Mechanically controlled or electronically controlled
154
What are the three types of mechanically controlled fuel injection pumps
Distributer fuel ejection, in-line fuel injection, unit fuel injection
155
Describe distributer fuel injection
It has one high-pressure pump and plunger that distributes and pumps fuel to a distribution head The high-pressure fuel is then diverted to each of the injector nozzles at each cylinder. The style is used by many small industrial and automotive diesel engines
156
Describe the inline fuel injection system
It is a self-contained unit that has its own cam and plunger for each cylinder. Each one of the plungers has a high-pressure line that goes to the individual cylinder injector
