Crankshaft and Related Components Fundamentals

Question 1

Crankshaft Nose

Answer 1

Usually at the front of shaft and is a mounting surface for the gear and vibration damper/hub

Question 2

Crankshaft Journal

Answer 2

Are the load bearing surfaces of the crankshaft, has main and rod journals

Question 3

Crankshaft Throw

Answer 3

The distance from the centerline of the main to the centerline of the rod

Question 4

Crankshaft Web

Answer 4

Connects the main and rod journals to form the throw of the crank

Question 5

Crankshaft Fillet

Answer 5

A rounded corner between the journal and the web, helps reduce stress of crank compared to square corners

Question 6

Crankshaft Counterweight

Answer 6

Masses of metal located opposite the rod journals

Question 7

Crankshaft Flange

Answer 7

Usually located on rear of crank and is the mounting surface for the flywheel

Question 8

Crankshaft Oil Passages

Answer 8

Internal drillings in the crank that provide a path for oil to flow from the main journals to the rod journals

Question 9

Crankshafts are usually manufactured in one of what two ways?

Answer 9

1. Casting

2. Forging

Question 10

What method is commonly used to harden crankshaft journals?

Answer 10

Induction Hardening - heated by electromagnetic induction and then quenched

Question 11

Diesel engine crankshafts are usually manufactured from?

Answer 11

Forged Alloy Steel

Question 12

The relative position of throws on a crank are determined based on what factors?

Answer 12

Number and Arrangement of cylinders
Firing order
Engine balance
Main bearing loads

Question 13

Nitriding

Answer 13

A chemical surface treatment that may be used to harden the journal surfaces

Question 14

Some of the effects of an unbalance engine are?

Answer 14

Run rough with excessive vibration and stress on components

Have reduced mechanical efficiency

Question 15

Inertia forces

Answer 15

Forces created by the acceleration and deceleration of the piston and con rod assembly

Question 16

Inertia forces are greatest at?

Answer 16

TDC & BDC

Question 17

Unbalanced couple

Answer 17

The result of two forces acting in opposite directions and in different planes

Question 18

Flywheel

Answer 18

Heavy mass of steel attached to the rear flange of the crankshaft

Question 19

Flywheels are matched to the engine based on what?

Answer 19

Number of cylinders
Displacement
Application

Question 20

What is the purpose of a vibration dampener?

Answer 20

To counteract or oppose the torsional forces acting on the crankshaft

Question 21

What are the two types of vibration dampers commonly used on diesel engines?

Answer 21

Rubber element

Viscous

Question 22

What are the two main functions of the crankshaft gear?

Answer 22

Transfers power from the crank to drive engine components and accessories
Time crankshaft to the cam and rest of motor

Question 23

What are the two common ways the crankshaft gears are attached to the crankshaft?

Answer 23

Pressed on and keyed

Bolted to a flange

Question 24

Crankshaft oil seals

Answer 24

Commonly referred to as front and rear main seals. Seals used in diesel engines are normally a one-piece lip seal

Question 25

What are the 3 basic purposes of friction type bearings?

Answer 25

Reduce friction between the moving parts of an engine
Support and maintain the alignment of a shaft or component
Provide a durable and replaceable wear surface

Question 26

Common bearing types

Answer 26

Bushing - Can be either full round or seamed
Shell type
Thrust - Can be either separate washers or part of the bearing shell

Question 27

4 basic properties that the material used in engine bearings must possess

Answer 27

Embeddability
Conformability
Fatigue resistance
Corrosion resistance

Question 28

Embeddability

Answer 28

Ability of the bearing lining to material to absorb dirt or hard foreign particles that are suspended in oil

Question 29

Conformability

Answer 29

The ability of the lining material to conform to shaft for minor damage and slight mis-allignment

Question 30

Fatigue resistance

Answer 30

Ability of a bearing to withstand continual loading without breaking down

Question 31

What are the 3 common layers found in a multi-layered bearing ?

Answer 31

Backing layer
Inner Layer
Overlay

Question 32

Bearing spread

Answer 32

Free spread diameter is the extra distance across tje parting faces of the bearing half
Is necessary is ensure proper seating of the bearing on the bore

Question 33

Crush relief

Answer 33

Bearing is tapered slightly at the parting line to provide relief from crush pushing bearing towards shaft at parting line

Question 34

Bearing grooves

Answer 34

Annular grooves
Spreader grooves
lateral groove
Thrust face

Question 35

Hydrodynamic lubrication

Answer 35

When the shaft acts as a pump forcing oil between the shaft and bearing surface

Question 36

Crankshafts used in medium and high speed diesel engines are usually:

Answer 36

One piece forged alloy steel

Question 37

List the four factors that determine the arrangement of the throws on a crankshaft?

Answer 37

1. Number and arrangement of cylinders
2. Firing order
3. Engine balance
4. Main bearing loads

Question 38

What are the 3 basic functions of the flywheel

Answer 38

1. Smoothes out engine operation by storing and releasing energy
2. Carry the ring gear
3. Provide a mounting and friction surface for clutch assembly

Question 39

What are the 2 purposes of the oil film between the bearing and the crankshaft journal?

Answer 39

1. Reduce friction

2. Carries the heat away from the bearing and journal