Engines Flashcards
What is torsional vibration
Rhythmic change in crankshaft speed
Wjat is primary balance
When a counterweight on the crankshaft offsets movement of piston and connecting rod
What is secondary balance
Movement of one piston off sets another, uses a second piston to offset another
What is the main purpose of a crankshaft
Convert linear motion of connecting rods into rotational energy
What is an elastomer dampener
Consists of an inner hub outer hub and rubber ring
What is a viscous dampener
Has fluid inside, silicone fluid acts like a spring
What isba combo dampener
A combo of viscous and elastomer dampener
What is a rotating pendulum vibrating absorber
Series of rollers that act between a drive hub and outer hub that allow relative movement to offset vibrations
What is a balance shaft dampeners
Run at 2x engine speed
What is a deep skirt block
Has a skirt below the crankshaft
What is a ladder frame block
All caps are connected as one, looks like a ladder
What is a tunnel bore block
Strongest block, small bore diesel, crankshaft tunnels into back of block when installed
What are the 4 types of blocks
- Deep skirt
2.ladder frame
3.tunnel bore
4.crossbolted
What Is a parent bore block
A block with no removable sleeves or liners
Cylinder sleeve blocks
Have replaceable liners that make your cylinder walls
What are the 3 types of liners
Dry-liner not exposed to coolant
Midstop-seat flange halfway down”mid”
Wet-outside of center exposed to coolant for heat transfer
What does the cross hatch pattern achieve
Helps retain oil, helps break in rings, as cross hatch wears oil consumption increases so does blowby. Power decreases
What are the main parts of a piston
Crown
Ring belt
Skirt
What is a slipper skirt piston design
A piston design that has a portion of the skirt removed on the non thrust sides of the piston to provide clearance for crankshaft counterweights
What is a monotherm piston
One piece piston design made entirely of alloyed stee, has a compact height and large reduction of material between skirt and crown
What is an articulating piston
Two piece piston design that uses a separate aluminum skirt connected to an alloy steel crown through a piston pin
What is a cam ground piston
An oval shaped piston that once warmed up rounds
What is a trunk piston
Piston design that is dimensionally longer than it is wide with a full piston skirt
Ehat are the 3 types of piston rings, what do they do
1.compression- for compression. Keystone shape notch up
2. Intermediate- for compression and oil taper face notch down
3.oil control- coiled expander ring, scraper rails
Crankshaft spacing is set to equal 720° of rotation so if you have 6 cylinders what is the degree of spacing per rod journal? What If you have 4 cylinders? What if you have 8 cylinders?
720°÷6=120° of spacing between rod journals
720°÷4=180° of spacing between rod journals
720°÷8=90° of spacing between rod journals
The amount of spacing between rod journals always adds up to 720° of rotation
So 720°÷ # of cyl= spacing between rod journal
What is slobber, what causes slobber
A mix of carbon, soot and condensation
Caused by excessive idle and low temp operation
What type of bearing is used on crankshaft main bearing sets
Friction bearing
If bearing clearance is too little what’s the cause
High oil pressure
If bearing clearance is too much whats the cause
Low oil pressure
What controls maximum oil pressure in an engine?
Relief valve
What would not enough liner protrusion cause?
It would cause the liners to wear excessively
What would cause liners to be damaged upon installation?
Too much liner protrusion
What is a cylinder contribution test
A test that determines a cylinders contribution to total engine power
When doing a compression test and you have low pressure on the dry test and good pressure on the wet test what does this mean
Bad rings
What are the three ways pistons are cooled?
Piston rings
Valve overlap
Cooling nozzles
What is the allowable wear for cylinder cross hatch
20%
If you have 10% of cylinder cross hatch left how much service life is left?
50% service life at 10% wear
Would you use and undersized or oversized bearing for a crankshaft that is worn or has been ground to undersize?
Undersized bearing for worn crankshaft or ground
Would you use and undersized or oversized bearing for a block that has been damaged and had the bearing bore re-bored?
You would use an oversized bearing for a bearing bore that has been re-bored
If you have too little liner protrusion what can you do?
You can add a shim underneath the liner flange
If liner protrusion is too high what can you do?
Swap it out for a liner with less protrusion. Very rarely is liners machined to lower liner protrusion
What must you do before you measure liner protrusion?
Clamp it in place
