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HET2 > 201h - Camshaft & Follower Fundamentals > Flashcards

201h - Camshaft & Follower Fundamentals Flashcards

1
Q

Camshaft gear train may also drive what components?

A

-Fuel injection pump
-fuel transfer pump
-oil pump
-tachometer
-Water pump

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2
Q

What is the role of camshaft lobes?

A

Convert rotary motion of camshaft into reciprocating motion of cam follower

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3
Q

What is the camshaft lobe nose?

A

Very top of the cam lobe, maximum lift point.

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4
Q

What is the camshaft base circle?

A

Base diameter of camshaft lobe. No valve opening.

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5
Q

What is camshaft lobe lift?

A

Distance cam follower moves as cam rotates.
Lift = Lobe height - base circle

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6
Q

What is camshaft duration?

A

Number of crankshaft degrees from valve opening to closing.

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7
Q

What are the camshaft manufacturing methods?

A
  • Casting
  • Machined or forged allow steel
  • Modular
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8
Q

What is the black coating on new cam lobes?

A

Coating which retains oil to prevent scuffing and promote quick break-in

(Molybdenum disulphide or manganese phosphate)

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9
Q

Where are modular camshafts used?

A

Large displacement engines for ease of manufacturing and maintenance

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10
Q

What are the two general camshaft locations within an engine?

A

In-block & overhead

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11
Q

What are 3 benefits of an overhead cam?

A
  • Fewer moving parts
  • Less friction
  • More accurate valve timing
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12
Q

How are in-block camshaft bushings held in place?

A

By a press fit

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13
Q

What type of bearings are used in overhead cams where the camshaft is removed vertically off the block?

A

Shell

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14
Q

Where is the cam thrust bearing located?

A

Behind the cam drive gear

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15
Q

What controls camshaft end play?

A

Thrust bearing

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16
Q

How are camshaft lobes lubricated?

A
  • spray from cam bearings
  • splashed from valve operating mechanisms
17
Q

What is the purpose of camshaft followers?

A

Convert rotary motion of the cam into reciprocating motion as they follow the profile of the cam lobe

18
Q

What are the AIT 3 basic types of cam followers?

A
  • solid
  • roller
  • hydraulic
19
Q

What are the two types of solid cam followers/lifters/tappets?

A
  • Straight body
  • Mushroom
20
Q

Straight body and mushroom are two types of what?

A

Solid type cam followers

21
Q

What advantage do mushroom cam followers have?

A

Greater surface area in contact with the cam lobe. Can withstand higher contact pressure.

22
Q

What provides the changing wear surface on solid cam followers?

A

Tapered cam lobe of 0.001”, slight convex bottom face of follower, and an offset centreline.

23
Q

On what type of cam followers is there a convex face and tapered lobe?

A

Solid type follower

24
Q

What do solid followers not compensate for which results in needing regular adjustments?

A

Regular wear and heat expansion.

25
Q

What benefits do roller type cam followers have?

A

Reduces friction, wear, and side thrust

26
Q

What type of cam follower has reduced friction, wear, and side thrust?

A

Roller type

27
Q

From a roller type follower, what benefits are there for the engine? (3)

A
  • Reduced frictional losses
  • Can handle higher operating loads
  • Quicker rate of valve opening and closing
28
Q

What are the benefits of hinged cam rollers?

A
  • Eliminate the need for lifter bores in engine block
  • Eliminates side thrust
29
Q

What type of cam roller eliminates side thrust entirely?

A

Hinged type roller follower

30
Q

What advantages do hydraulic lifters have?

A
  • Compensate for heat expansion and normal wear, eliminating valve clearance adjustments
  • Quieter valve train
31
Q

How are camshafts driven?

A
  • Gear
  • Chain
32
Q

Do idler gears affect the speed of camshaft rotation?

A

No

33
Q

How do idler gears affect camshaft rotation?

A

No affect to rotation speed
Do change rotation direction
- even # gears = opposite direction
- odd # gears = same direction

34
Q

What are the two types of cam chains used in heavy equipment?

A
  • Silent
  • Roller (stronger)
35
Q

What is lobe separation angle?

A

Number of degrees that the intake and exhaust lobes are offset from each other.

36
Q

What will incorrect camshaft timing result in? (4)

A
  • Altered valve opening and closing points
  • Poor engine performance
  • Damage to engine components
  • Alter fuel injection timing on engine camshaft actuated injectors

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