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millwright level 2 > chain drives > Flashcards

chain drives Flashcards

1
Q

power transmission chains are used as a positive drive to transmit power between widely spaced ?

A

shafts the chain engages with toothed wheels called sprockets

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2
Q

name some power transmission limitations

A

do not slip on overload
adequate lubrication is hard to maintain
- service life is less than that of gears

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2
Q

what are power transmission chain characteristics ?

A

provide positive drive
- highly efficient 98% or better
- can be used with any distance between shaft centres
- number of shaft can be driven by a single shaft
-

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3
Q

two main designs of power transmission chains used they are?

A

roller chain and silent chain

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4
Q

chains are made of ?

A

hardened carbon steel
-stainless steel for corrosion
-synthtics such as nylon and various plastics
-

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5
Q

two basic types of links?

A

pin links and roller links

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5
Q

cotter pins are usually used on what numbers of chain?

A

80 chains and larger

spring clip retainers are used on#25 to #60

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6
Q

what is a connecting link?

A

unriveted link in a chain
-consists of a pin link with pins that are drilled for cotter pins or grooved at outer ends for spring clip

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7
Q

the connecting link changes the chains length by?

A

two pitches

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8
Q

another name for single pitch offset link?

A

half link- changes the length of the chain by one pitch

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9
Q

where is light duty chain used?

A

used on drives where space is restricted ,they have lower power ratings

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10
Q

what number is the most common light duty chain its used on garage doors?

A

41

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11
Q

true or false double strand chain is 1.7 times stronger than single strand ?

A

true

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12
Q

what is oil field chain intended for ?

A

severe service ond rilling rigs , uses press fit centre plates

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13
Q

name two types of pre lubricated chain?

A

sintered bushing chain -uses a powdered metal bushing lubricant is squeezed out under load

-0-ring chain -provide life time lubrication and exclude contaminates - can operate at high temps with special o-rings

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13
Q

where are pre lubricated chains used ?

A

designed for applications that do not permit regular lubrication.

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14
Q

the load capacity of a sintered chain is how much less

A

10% less than a standard chain

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15
Q

What corrosion resistant material is corrosion resistant chain produced with

A

stainless steel or by plating standard chain with a corrosion resistant coating such as nickel or a zinc compound

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16
Q

true or false -
Stainless steel does not have the tensile strength of carbon steel, and therefore load capacity is sacrifice for corrosion resistance

A

true

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17
Q

Plated chain has the same load capacity of standard chain, but it protects the integrity of the chain in a corrosive environment. However, the corrosion protective is lost when.

A

the platting wears off

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18
Q

Synthetic chains are designed for very light service. Such as instrument drives in office machines.true or false

A

true

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19
Q

Wearwood synthetic Chan applications be

A

food handling and process equipment
-computer equipment
-instrument drives
-

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19
Q

what are synthetic chain advantages

A

light weight 15%-20% the weight of steel

  • no lube required
    -all links are master links
    interchangeable with steel chain
    -corrosion resistance is good
    -
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20
Q

why is double pitch chain lighter ?

A

has half the number of pins and bushing and rollers, used for long spans and slow to moderate speeds with low HP.

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21
Q

instead of rollers what does roller less chain use?

A

bushings on pins at each joint -less expensive Tham standard roller chain

designated by the number 5 in the right hand part of the chain number

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21
Q

double pitch chains fits ?

A

standard sprockets since rollers and width are the same as standard pitch chain

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22
Q

where is silent chain used?

A

transmitting high horse power in a small space such as in chain driven speed changers
-high speed drives
-precision timing

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23
Q

silent chain is also called?

A

timing chain-contains tooth plates instead of rollers

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24
Q

where is a joining pin or connecting link used?

A

used on toothed links to change the length by two pitches, convenience way for assembling the chain in the field

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25
Q

where is a hunting link used ?

A

used on a tooth link when an odd number of pitches is required - an even pitch number is recommended

26
Q

what are the 3 silent chain designs ?

A

side guides
centre guides
for serpentine drives

26
Q

why do you do a chain inspection on a broken chain?

A

to try to discover the root cause of chain drive failure

27
Q

silent chain advantages ?

A

high efficiency and HP in a narrow width
-lighter bearing load
-positive drive and durability
-smooth performance
-load shared by a number of teeth

28
Q

how to measure the chain length?

A

measure old chain and divide by the pitch
-lay new chain beside the old chain
-

29
Q

the master link must be installed with the closed end of the spring clip in what direction ?

A

the direction of travel

29
Q

how do you remove old chain?

A

chain breaker
-torch -grinder

30
Q

what kind of fit does a master link us?

A

slip fit

31
Q

slip fitted plate reduces the working capacity by ?

A

30%

32
Q

true or false? press fit side plates significantly reduce the capacity of the chain?

A

false .

33
Q

multiple strand chains with press fit centres plates are used in ?

A

severe service applications such as drilling rigs

33
Q

chains can be adjusted by ?

A

adjustable centres
using lighting idlers

34
Q

What is the single most important factor in controlling the chains wear?

A

lubrication

35
Q

What oil should you use when lubricating chains?

A

highest viscosity and still flows into the joint

36
Q

manual drip feel lubrication is intended for ?

A

low speed drives under 600 feet per minute

36
Q

name 3 methods of chain lubrication?

A

manual or drip feed
bath
forced

37
Q

forced lubrication is intended for ?

A

heavily loaded drives operating above the speed limits of bath lubricaiton

37
Q

bath lubrication is intended for chains at approx ?

A

1500 feet per minute

38
Q

a warn sprocket destroys a new chain never install a new chain on a worn out sprocket

A
39
Q

what is a sprocket ?

A

toothed wheels designed to mesh with power transmission chains

40
Q

sprockets can be made of ?

A

allow cast iron -very large sprockets
medium carbon steel- small, medium and large sprockets
plastic-light duty sprockets

41
Q

where are sprockets used ?

A

-on the drive unit
as idlers to tension chains
-on drives that provide accurate timing
-in roll cases

42
Q

what’s the problem with small wrap angle ?

A

the chain may jump the teeth when operated at its designed maximum load

43
Q

the wrap angle is always 120 deg when the ratio is?

A

3:1 or less regardless of the centre distance

44
Q

a sprocket with fewer teeth results in ?

A

increases wear and vibration on the sprocket and chain

45
Q

if a chain drive does not provide satisfactory service life because a smaller sprocket is to small what would you do ?

A

increase the centre distance
- change the speed using a jack shaft

46
Q

vertical and angle drives are often used were?

A

industrial drives

47
Q

sprockets with an odd number of teeth are called ?

A

hunting tooth sprockets

48
Q

what is the advantage of a double pitch chain sprocket ?

A

wear is distributed over twice as many teeth

49
Q

when ever possible use a sprocket with an odd number of teeth why?

A

different tooth engages with the chain on each revolution

50
Q

where are idler sprockets used?

A

used as chain tensioners on fixed centre drives ,they mount on slack span reduce wear on the chain and sprocket

51
Q

idlers can be used to ?

A

prevent chain whip
improve chain wrap
guide the chain around obstacles
provide reverse rotation of a sprocket outside the chain

52
Q

hardened tooth sprockets are common and intended for greater wear resistance , they are beneficial when ?

A

the number of teeth is 20 or less
on drives that are heavily loaded
in abrasive conditions
on high speed drives
on drives that require extremely long life

53
Q

hub style sprockets type
a
b
c
d

A

a= flat plate style sprocket can be welded or bolted
B= type b have a hub on one side can be mounted in smaller places
C= hubs on both sides
D=split design sprocket

53
Q

keyless adapters are common on machines that require what?

A

accurate timing

54
Q

tapered bore hub allows you to ?

A

use a tapered adapter bushing

55
Q

what causes side wear on a sprocket ?

A

misalignment of the sprocket

56
Q

what causes hooked teeth on a sprocket?

A

causes by wear caused by over tension inadequate lubrication abrasives or overload

57
Q

after you have tightened the pull up bolts there should be how big of a gap between the sprocket and flange ?

A

1/4-1/8 gap

58
Q

should you use more or less tension on a vertical or angle drive that on a horizontal drive?

A

more tension

59
Q

should the slack be span on the top or bottom of a drive?

A

bottom

60
Q

which sprockets would you use in an abrasive environment

A

harden tooth sprokets

61
Q

when you see a chain not meeting properly with a sprocket and is pilling up on the sprocket what’s wrong

A

the chain or sprocket is worn

61
Q

what is the advantage of a b type sprocket?

A

can bemoaned closer to the support bearing

62
Q
A

millwright level 2 (13 decks)

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