camshaft

Question 1

function of the cam shaft

Answer 1

.Controls the opening and closing of the valves
.Changes rotary motion into reciprocating motion
.Actuates the injector operating mechanism on engines with fuel injectors

Question 2

Depending on engine design camshaft gear train may also drive

Answer 2

.Fuel injector pump
.Fuel transfer pump
.Tachometer
.oil pump

Question 3

Camshaft components

Answer 3

Nose
Keyway 
Journals 
Injector lobe 
Valve lobes

Question 4

Camshaft nose

Answer 4

mounting surface for camshaft drive gear or sprocket

Question 5

camshaft Keyway

Answer 5

maintains alignment between camshaft and drive gears

Question 6

Journals

Answer 6

Load bearing surface that supports the camshaft in the cylinder block or head

Question 7

camshaft lobes

Answer 7

convert rotary motion of the camshaft into reciprocating motion of the cam follower

Question 8

Auxiliary drive gear on a camshaft

Answer 8

machined onto the shaft used to drive oil pump or tachometer

Question 9

cam lobe design controls

Answer 9

valve timing as well as rate at which valves open and close

Question 10

three factors that will determine camshaft lobe design

Answer 10

hoarse power
speed of operation
naturally aspirated or turbocharged

Question 11

camshaft lobe terminology

Answer 11

Nose
Lift
Ramp
Base circle

Question 12

Nose of a cam lobe

Answer 12

maximum point of lift

Question 13

Camshaft lobe ramp

Answer 13

is the slope the follower will ride up and down on

There is an opening and closing ramp on all camshaft lobes

Question 14

Cam lobe Base circle

Answer 14

is the base diameter of the camshaft lobe

at this point there is no valve opening

Question 15

Cam lobe lift

Answer 15

Is the distance the cam follower moves as it travels to the top of the cam lobe
Lift can be determined by subtracting base circle diameter from lobe height

Question 16

Duration

Answer 16

the number of degrees between the point where the valve opens and the valve closes
actual amount of degrees is measured in crankshaft rotation

Question 17

three types of camshaft construction

Answer 17

Casting
Machined or forged from alloy steel
Assembled from components

Question 18

Cast camshafts

Answer 18

used in low hoarse power or light and medium duty diesel engines
Can be chipped or broken easily if not handled with care

Question 19

Steel camshafts

Answer 19

used in engines where extreme loads are placed on the camshaft
journals and lobes are hardened to improve durability

Question 20

Molybdenum disulphide and manganese phosphate are used on cast camshafts for

Answer 20

pressure resistant and anti wear properties

retains oil prevents scuffing and promotes quick break in of the lobes when engine is first started

Question 21

Modular camshafts

Answer 21

used in large displacement engines

Question 22

camshaft locations

Answer 22

In-block and overhead

Question 23

Advantages of an overhead camshaft

Answer 23

.Fewer moving parts
.Less friction
.More accurate vale timing

Question 24

camshaft bearings

Answer 24

used to support the camshaft and control end play

Question 25

most common method of controlling camshaft end play

Answer 25

thrust washer or plate | usually located behind the camshaft drive gear and bolts to the cylinder block

Question 26

purpose of the cam follower

Answer 26

provides a link between the cam lobe and the valve operating mechanism converts rotary motion into reciprocating

Question 27

Types of cam followers

Answer 27

Solid roller Hydraulic

Question 28

two types of solid followers

Answer 28

straight body | mushroom

Question 29

Advantage of solid type mushroom lifter

Answer 29

have a greater surface area therefore will withstand higher contact pressure

Question 30

three factors of solid followers that provide a changing wear surface

Answer 30

Slight taper from one edge to the other aprox .001" bottom face will not be flat but convex (crowned) Lifter centerline is offset from the cam lobe center line

Question 31

Advantage of a slight crown on a solid follower

Answer 31

allows a larger contact point and prevents edge loading of the cam lobes

Question 32

Why must valve operating mechanism have clearance or lash when used with solid type followers

Answer 32

to allow for heat expansion

Question 33

Roller type lifters

Answer 33

can be solid or hydraulic in design bottom of the lifter has a wheel or roller retained by a pin and supported by a bushing

Question 34

to prevent roller type lifter from turning in the lifter bore

Answer 34

positioning mechanism will be used

Question 35

Three advantages to a roller type lifter

Answer 35

reduce frictional loss can handle much higher operating loads allow for quicker open and close rates of valves

Question 36

Advantage of a hinged type roller

Answer 36

eliminates the need for follower bores as well as side thrust created by conventional roller followers also can handle very high operating loads

Question 37

Hinged roller design normally used on

Answer 37

engines with mechanically actuated fuel injectors

Question 38

two advantages of a hydraulic lifter

Answer 38

compensates for normal heat expansion and normal wear eliminating the need for valve clearance (lash) and periodic adjustments reduced noise because components are in continual contact

Question 39

hydraulic lifters are normally used in small displacement diesel engines because

Answer 39

cost and reliability

Question 40

Internal leakage of a hydraulic lifter under pressure is referred to as

Answer 40

the leakage rate

Question 41

OHV and OHC

Answer 41

overhead valve engines | overhead camshaft

Question 42

camshaft drive mechanism

Answer 42

provide a positive method to drive the camshaft and any camshaft driven components establish a relationship between crankshaft and camshaft for timing

Question 43

Two methods for driving a camshaft

Answer 43

gears or chains

Question 44

idler gears in an engine are used when

Answer 44

physical distance between the camshaft and the crankshaft is to great

Question 45

two types of timing chains

Answer 45

silent type for light and medium duty engines | roller type for heavy duty engines

Question 46

one of the most critical steps in reassembling an engine is

Answer 46

camshaft timing as it determines firing order and correct valve timing

Question 47

Incorrect camshaft timing will result in

Answer 47

altered valve opening and closing points poor engine performance damage to the engine components altered fuel injection timing on engine camshaft actuated injectors

Question 48

another method of camshaft timing

Answer 48

offset keys | can be installed in either direction to retard or advance cam timing

Question 49

A round eccentric on a camshaft would be used for what purpose

Answer 49

to drive an engine mounted fuel transfer pump

Question 50

two locations to measure gear backlash on the engine

Answer 50

between the crankshaft and idler and the idler and the camshaft

Question 51

worn teeth on a gear will result in

Answer 51

retarded timing

Question 52

chain drive slack should not exceed more than

Answer 52

1/2 "

Question 53

mushroom type lifters must be removed after the camshaft because

Answer 53

the large surface of the lifter will not allow them to be removed from the top side of the cylinder block

Question 54

two indications of a bent camshaft

Answer 54

binding or a tight spot when rotating the camshaft in the cylinder block uneven cam bearing wear

Question 55

method used for measuring fuel injector lobes on a camshaft

Answer 55

flat block and feeler gauge

Question 56

when checking solid type lifter for reuse

Answer 56

check for scuffing and scoring on the lifter sides scuffing, scoring and pitting on the face must have convex shape

Question 57

extreme cupping of a solid type lifter

Answer 57

lack of lubrication long service life poor maintenance

Question 58

excessive camshaft end play will cause

Answer 58

drive gear noise and excessive wear to components

Question 59

when removing camshaft bushings from their bores

Answer 59

use a special driver or puller

Question 60

after camshaft bearings are installed you should check for

Answer 60

proper alignment of the oil holes using a alignment tool

Question 61

if the camshaft gear must be heated for installation the thrust washer must not be

Answer 61

lubricated

Question 62

lobes require special lubrication when being installed because

Answer 62

scuffing action between lifters and cam lobe | manufacture my require special EP lubricant (extreme pressure)

Question 63

three factors that may cause camshaft end play

Answer 63

thrust plate installed backward thrust plate misalignment foreign material between the thrust plate and camshaft or gear