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millwright level 2 > gearing fundamentals > Flashcards

gearing fundamentals Flashcards

1
Q

what are two types of gear drives?

A

open gear drives and enclosed gear drives

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2
Q

what are open gear drives ?

A

gears that are exposed to the outside environment

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3
Q

whaat are enclosed gear drives?

A

gear drives contained with in a gearbox with lubrication supply
can be either oil or grease lubricated

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4
Q

what is a gear set?

A

matched pair of gears manufactured together

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5
Q

what is a gear train?

A

when two or more gear mesh or work together

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6
Q

what is a pinion?

A

when two gears that have different number of gears mesh or work together

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7
Q

what is a crown gear?

A

in beval and hypoid gear sets there are two mating gears
smaller one is a pinion
larger one is a ring gear (crown)

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8
Q

what is the drive gear power in and power out

A

power in is the input gear train that causes mating gears to turn
- power out is the output gear train that the drive gear forces to turn

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9
Q

what is direct drive?

A

when the input speed of the gearbox is the same as the output speed

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10
Q

what is a speed reducer?

A

a gear train with a slower output speed that input speed occurs when a small gear drives a larger gear out put has more torque but less speed

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11
Q

what is a speed increaser

A

a gear train with a faster output speed that input speed occurs when a large gear drives a smaller gear less torque but same speed

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12
Q

one issue with over hung gears?

A

tend to have more shaft deflection under heavy loads because of a bearing support on only one side of the gear

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13
Q

what are straddle mounted gears

A

are mounted between two bearings ,stronger and less shaft deflection than overhung gears

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14
Q

what are internal gears ?

A

have teeth on the inside diameter of the gear , operate more smoothly than external gears , more tooth contact

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15
Q

what is a compound gear train?

A

have 3 or more shafts and four or more gears,
useful where a higher reduction or speed increase is important

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16
Q

substantial gear reductions can be achieved by using what ?

A

compound gear trains

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17
Q

what is end play?

A

when the gear shaft is allowed to move axially

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18
Q

what is axis of rotation?

A

centre line around which a gear or parts revolve
usually centreline of shaft

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19
Q

what is a floating gear or shaft ?

A

lists when one gear os shaft is allowed to move axially to its best position

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20
Q

what gears can be right hand or left hand gears?

A

helix angle

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21
Q

what is chordal thickness?

A

the thickness of the gear tooth the pitch of circle indicated tooth strength

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22
Q

what does an involute do ?

A

makes meshing with the mating gear quieter and smoother, has radius across the flank and the face of the tooth

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23
Q

what is one method in checking contact pattern?

A

use Prussian blue mixed with oil or red lead

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24
Q

where should back lash be checked?

A

the point at closest engagement

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25
Q

what is diametral pitch?

A

is the number of teeth on the gear divided by the pitch diameter

lower the number bigger the gear teeth

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26
Q

what is AGMA stand for

A

american gear manufactures

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27
Q

what is binding and what causes it

A

check with out a load
binding is where tight spots are felt

lack of backlash
incorrect center distances
gear center out of tolerance
bent shafts
thermal expansion

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28
Q

what is a pressure angle?

A

angle of the gear tooth, gear trains have pressure angles of 14.5 deg to 20 deg

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29
Q

true or false ?
meshing gears must have the same pressure angle?

A

true

30
Q

what are two basic gear teeth profiles?and what are the differences

A

involute and straight
involute has a slight curve on the face of the gear

-straight have straight faces and are very noisy not suitable for high speed or high power applications unless speeds are very low

31
Q

when an even amount of gears mesh with each other the last gear rotates ?

A

first gear turns clockwise last gear turn counter clock wise

32
Q

if an odd number of gears mesh with each other the last one rotates ?

A

same direction as the first gear

33
Q

an internal gear set has both gears moving in ?

A

the same direction

34
Q

paraelle shafts are?

A

equal distances apart on two diff planes

spur gears
helical gears
double helical gears
herring bone gerars

34
Q

what do idlers do?

A

they change the direction of rotation or keep it the same
-can connect two gears with a c-c distance that is greater than the gears

35
Q

spur gears can be used in 3 basic arrangements ?

A

external
internal
rack and pinon

35
Q

what are intersecting shafts ?

A

shafts are at 90 deg to each other but on the same plane

beval gears
mitre gears

36
Q

what is crossing over at 90 deg?

A

worm gears
hypoid gears
helical gears

37
Q

spur gears develop no axial thrust unless they are misaligned because?

A

there teeth are straight

can contain many types of material from metallic to non metallic

38
Q

single helical gears have the teeth cut at an angle to the shaft axis true or false

A

true

39
Q

what are the common angle on a helical gear ?

A

7-12deg

40
Q

what is an advantage of of using a double helical gear?

A

axial thrust is canceled by the opposite row of teeth

41
Q

where are herringbone gears reccomened ?

A

for high speed applications and heavy loads
must be mounted on shafts that are parallel

42
Q

where are bevel gears used ?

A

used on shafts that have intersecting axes most common bevel gear intersects at 90 deg

43
Q

true or false bevel gears develop axial thrust loads and radial thrust loads?

A

true require a bearing that can handle both types of load

43
Q

why are spiral bevel gears stronger than straight bevel gears ?

A

they have more teeth in contact at the same time ,manufactured in pairs and to mesh must be of opposite hands

44
Q

do zerol bevel gears have axial thrust like spiral bell gears ?

A

no and they are smoother and quieter than straight cut bevel gears

44
Q

whats the difference between a throated and non throated worm

A

non throated worm is shaped like a cyclinder
- throated worm is shaped like a hour glass

45
Q

a simple planetary gear set consists of three parts?

A

a sun gear
a carrier with a planet gears mounted to it
- a ring gear

46
Q

The pinion gear is usually the smaller gear in the set, true or false

A

true

46
Q

Gears are positive transmission devices that are used were there can be no slippage true or false

A

true

47
Q

Most gears are made to the standards set by the AGMA true or false

A

true

48
Q

The flank of the gear tooth is located in that addendum true or false

A

true

49
Q

I drive using helical gears can have the gear set up so they are overhung true or false

A

true

49
Q

In a compound gear system, there can be six and four shafts, true or false

A

true

50
Q

A gear set that has a 20° pressure angle is stronger than a gear set with a 14 1/2° pressure angle

A

true

51
Q

It is best to measure the backlash of a gear sat at the pitch circle, true or false

A

true

52
Q

A gear with the diametral pitch of four has very small teeth, true or false

A

true

52
Q

A gear train has 15 gears meshing together with the input gear rotation in the clockwise direction. The output gear should turn in counter clockwise direction, true or false.

A

false odd number of gears last gear turns the same as the first gear

53
Q

Helical gears of parallel shops must use gears of the opposite hand, true or false

A

true

53
Q

A gearbox has a 10 to 1 reduction driven by a 1 hp electric motor at 1750 RPM. The output from the gearbox is 10 HP at a speed of about 175 hp.

A

false , hp cannot be increased in a gear set

54
Q

Double helical gears are good for high speeds and heavy loads, true or false

A

true

55
Q

A spur gear set that intersects at 90° must be of the same hand true or false

A

false spur gears are straight cut and do not intersect

56
Q

Herringbone, gears, or light duty drivers, true or false

A

false they are heavy duty

57
Q

Spiral bevel gears look very similar to hypoid gear’s true or false

A

true

57
Q

Hypoid gear’s have high, sliding action and require an EP additive in the oil true or false

A

true

58
Q

The heel of a hypoid or spiral bevel gear is near the inner circle true or false

A

false

59
Q

Worm gear have a lot of sliding action, true or false

A

true

60
Q

Warm gears, or less efficient than most other types of gears, true or false

A

true
higher friction heat and wear means greater energy loss

61
Q

Double throated worm and warm will Gear still have a maximum gear tooth contact true or false

A

true

millwright level 2 (13 decks)

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