gearing fundamentals

Question 1

what are two types of gear drives?

Answer 1

open gear drives and enclosed gear drives

Question 2

what are open gear drives ?

Answer 2

gears that are exposed to the outside environment

Question 3

whaat are enclosed gear drives?

Answer 3

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

Question 4

what is a gear set?

Answer 4

matched pair of gears manufactured together

Question 5

what is a gear train?

Answer 5

when two or more gear mesh or work together

Question 6

what is a pinion?

Answer 6

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

Question 7

what is a crown gear?

Answer 7

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

Question 8

what is the drive gear power in and power out

Answer 8

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

Question 9

what is direct drive?

Answer 9

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

Question 10

what is a speed reducer?

Answer 10

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

Question 11

what is a speed increaser

Answer 11

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

Question 12

one issue with over hung gears?

Answer 12

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

Question 13

what are straddle mounted gears

Answer 13

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

Question 14

what are internal gears ?

Answer 14

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

Question 15

what is a compound gear train?

Answer 15

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

Question 16

substantial gear reductions can be achieved by using what ?

Answer 16

compound gear trains

Question 17

what is end play?

Answer 17

when the gear shaft is allowed to move axially

Question 18

what is axis of rotation?

Answer 18

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

Question 19

what is a floating gear or shaft ?

Answer 19

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

Question 20

what gears can be right hand or left hand gears?

Answer 20

helix angle

Question 21

what is chordal thickness?

Answer 21

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

Question 22

what does an involute do ?

Answer 22

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

Question 23

what is one method in checking contact pattern?

Answer 23

use Prussian blue mixed with oil or red lead

Question 24

where should back lash be checked?

Answer 24

the point at closest engagement

Question 25

what is diametral pitch?

Answer 25

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

Question 26

what is AGMA stand for

Answer 26

american gear manufactures

Question 27

what is binding and what causes it

Answer 27

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

Question 28

what is a pressure angle?

Answer 28

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

Question 29

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

Answer 29

true

Question 30

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

Answer 30

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

Question 31

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

Answer 31

first gear turns clockwise last gear turn counter clock wise

Question 32

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

Answer 32

same direction as the first gear

Question 33

an internal gear set has both gears moving in ?

Answer 33

the same direction

Question 34

paraelle shafts are?

Answer 34

equal distances apart on two diff planes spur gears helical gears double helical gears herring bone gerars

Question 34

what do idlers do?

Answer 34

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

Question 35

spur gears can be used in 3 basic arrangements ?

Answer 35

external internal rack and pinon

Question 35

what are intersecting shafts ?

Answer 35

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

Question 36

what is crossing over at 90 deg?

Answer 36

worm gears hypoid gears helical gears

Question 37

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

Answer 37

there teeth are straight can contain many types of material from metallic to non metallic

Question 38

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

Answer 38

true

Question 39

what are the common angle on a helical gear ?

Answer 39

7-12deg

Question 40

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

Answer 40

axial thrust is canceled by the opposite row of teeth

Question 41

where are herringbone gears reccomened ?

Answer 41

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

Question 42

where are bevel gears used ?

Answer 42

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

Question 43

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

Answer 43

true require a bearing that can handle both types of load

Question 43

why are spiral bevel gears stronger than straight bevel gears ?

Answer 43

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

Question 44

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

Answer 44

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

Question 44

whats the difference between a throated and non throated worm

Answer 44

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

Question 45

a simple planetary gear set consists of three parts?

Answer 45

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

Question 46

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

Answer 46

true

Question 46

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

Answer 46

true

Question 47

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

Answer 47

true

Question 48

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

Answer 48

true

Question 49

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

Answer 49

true

Question 49

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

Answer 49

true

Question 50

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

Answer 50

true

Question 51

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

Answer 51

true

Question 52

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

Answer 52

true

Question 52

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.

Answer 52

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

Question 53

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

Answer 53

true

Question 53

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.

Answer 53

false , hp cannot be increased in a gear set

Question 54

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

Answer 54

true

Question 55

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

Answer 55

false spur gears are straight cut and do not intersect

Question 56

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

Answer 56

false they are heavy duty

Question 57

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

Answer 57

true

Question 57

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

Answer 57

true

Question 58

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

Answer 58

false

Question 59

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

Answer 59

true

Question 60

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

Answer 60

true higher friction heat and wear means greater energy loss

Question 61

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

Answer 61

true