Stationary Engines Flashcards
What should be done before working on larger engines?
If it has a barring device, be sure it is locked out. Pin, lock and tag the flywheel
What is an engine?
A mechanical device that converts the chemical energy stored in a fuel to heat, and then mechanical energy.
What is the formula for work?
Work=force X distance
What is power?
Power is the rate at which work is being done
What are the different types of power?
Horsepower
Friction horsepower- frictional losses
Indicated horsepower- no losses, theoretical
Brake hp- indicated-frictional
What does a vacuum gauge read at atmospheric pressure?
29.92 inches Mercury
What is a square engine?
When the stroke and bore are both the same dimension
What is an undersquare engine?
When the bore is smaller than the stroke. The majority of industrial engines are undersquare
How is piston displacement determined?
Area of bore X length of stroke
What is engine displacement?
The volume swept by all the Pistons
What is clearance volume?
The volume remains when piston is at TDC
What is blowby?
It is the leakage of burned and unburned gasses past the compression rings into the crankcase
What are the four strokes in one cycle of a four stroke?
Intake - suck
Compression - squeeze
Power - bang
Exhaust - blow
How do you tell if an engine runs cw or ccw?
View the engine from main power takeoff or flywheel end. If it rotates to the right its a CW left its CCW
What are the six common cylinder and crankshaft arrangements?
In line, v type, integral, opposed piston, horizontally opposed, radial
What are the two types of ignition methods?
Compression ignition (CI) - diesels Spark ignition (SI)
What is the engine block?
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
What are the drilled passages in the block for?
To carry lubricating fluid to the bearing areas
What other things are in the block?
Water jackets, coolant passages, and cooling deflectors to carry the coolant to and from the various parts of the engine
Describe a one piece block
It is the most common type of block. The main bearing caps under the crankshaft therefore it is called underslung crankshaft
Describe a multi piece block?
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
What should not be used for cleaning aluminum engine components?
Caustics, as they attack and corrode aluminum.
When cleaning a head, for servicing, what should be done with oil galleries?
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
How do you check the block for cracks?
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
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
If the block deck is resurfaced what must be done?
Because the piston to head clearance may change the spec should be checked.
What is the maximum deviation of the main bearing bores?
No more than half the maximum allowable main bearing clearance, in new condition.
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
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.
What is line boring?
It is a procedure that uses a boring bar to machine the main bearing bores.
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
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
Where is the highest wear area in the cylinder?
Near the top due to high temperatures, pressures, and minimum lubrication.
What are some methods to treat the inside of the cylinder liner to reduce the rate of wear?
Induction hardening, hard chroming, nitriding
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
How can a liner with minor cavitation be salvaged?
Reinstall it 90° from its original position
What can cause excessive or premature liner wear?
Dust or fine particles that come through the air filter, or leaks in the intake system
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
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.
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
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
What should be measured when reinstalling a wet liner?
The liner counterbore should be measured for depth and flatness using a depth micrometer
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
What are crankshafts made from?
Forged alloy steel which is either flame or induction hardened.
What are the main parts of the crankshaft?
Main bearing journals, connecting rod journals or throws, webs, counterweights
What are the counterweights for?
They are used to balance the rotating mass opposite of the Rod throws.
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
Where is the thrust face normally located?
Near the flywheel end of the crankshaft
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
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.
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
How is the flywheel used in lockout?
It can be pinned and blocked to prevent rotation
What is another name for a vibration dampener
A balancer or harmonic balancer
Where are vibration dampeners located?
They are on the opposite end of the flywheel and act like a torsional shock absorber
What are the different types of vibration dampeners?
Rubber mounted, viscous type, spring type.
What type of vibration dampeners are we repairable?
Only the spring type are repairable.
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
What is another name for plain bearings?
Journal bearings
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
What is fatigue strength
The ability of the bearing to withstand shock loads without flaking or cracking
What is embeddability?
The ability of the bearing to absorb small particles of dirt preventing damage to the shaft
What is conformability
The ability to mould itself to the imperfections of the crank journal