Gears

Question 1

defines the average number of teeth in contact at any one time

Answer 1

contact ratio

Question 2

A minimum contact ratio for smooth operation

Answer 2

1.2

Question 3

Most spur gearsets will have contact ratios between

Answer 3

1.4 and 2.

Question 4

A disadvantage of unequal-addendum tooth forms is an

Answer 4

increase in sliding velocity at the tooth tip.

Question 5

Interference (and undercutting caused by manufacturing tools) can be prevented simply by

Answer 5

avoiding gears with too few teeth

Question 6

As the number of teeth is reduced for a fixed diameter gear,

Answer 6

the teeth must become larger.

Question 7

Severe undercutting will promote

Answer 7

promote early tooth failure.

Question 8

arc length along the pitch circle circumference measured from a point on one tooth to the same point on the next.

Answer 8

circular pitch

Question 9

defines the tooth size.

Answer 9

circular pitch

Question 10

tooth is measured along the axis of the gear.

Answer 10

face width

Question 11

tooth thickness is measured at the

Answer 11

pitch circle,

Question 12

tooth space width is slightly larger

Answer 12

tooth thickness.

Question 13

Tooth space width - tooth thickness

Answer 13

backlash

Question 14

dedendum is slightly larger

Answer 14

addendum

Question 15

tip of one mating tooth

Answer 15

(addendum circle)

Question 16

bottom of the tooth space

Answer 16

(dedendum circle).

Question 17

tooth height is defined by the

Answer 17

addendum

Question 18

tooth height is defined by the

Answer 18

addendum and dedendum

Question 19

(AGMA)

Answer 19

American Gear Manufacturers Association

Question 20

They define a spectrum of quality numbers and tolerances ranging from

Answer 20

lowest (3) to the highest precision (16).

Question 21

backlash can cause potentially

Answer 21

“hunting”

Question 22

back-to-back on the same shaft that can be rotated slightly at assembly with respect to one another,

Answer 22

antibacklash gears

Question 23

Another factor affected by changing center distance is

Answer 23

backlash.

Question 24

clearance between mating teeth measured at the pitch circle

Answer 24

Backlash

Question 25

As the center distance increases

Answer 25

pressure angle and vice versa

Question 26

The common normal is

Answer 26

still tangent to the two base circles and still goes through the pitch point.

Question 27

The velocity ratio is unchanged despite the shift in center distance.

Answer 27

Unchanged

Question 28

center distance errors ____ the velocity ratio.

Answer 28

Do not affect

Question 29

the gear tooth form is not an involute, then an error in center distance will violate the fundamental law, and there will be variation, or

Answer 29

"ripple,"

Question 30

There will also be an ideal center distance ( CD ) that will give us the nominal pitch diameters for which the gears were designed. U

Answer 30

center distance

Question 31

defined as the angle between the axis of transmission or line of action ( common normal)

Answer 31

pressure angle

Question 32

direction of velocity at the pitch point

Answer 32

pressure angle

Question 33

distance along the pitch circle within the mesh

Answer 33

arc of action

Question 34

subtended by these points and the line of centers

Answer 34

subtended by these points and the line of centers

Question 35

The arc of action on both pinion and gear pitch circles

Answer 35

The arc of action on both pinion and gear pitch circles

Question 36

The distance along the line of action between these points within the mesh i

Answer 36

length of action,

Question 37

common normal of the tooth profiles, at all contact points within the mesh

Answer 37

pitch point

Question 38

The ratio of the driving gear radius to the driven gear radius

Answer 38

remains constant as the teeth move into and out of mesh.

Question 39

curves at the contact point,

Answer 39

common tangent

Question 40

perpendicular to the common tangent.

Answer 40

common normal

Question 41

common normal, which is also the

Answer 41

axis of transmission,

Question 42

The amount of tooth that sticks out

Answer 42

addendum,

Question 43

The cylinders from which the strings are unwrapp

Answer 43

base circles

Question 44

base circles are necessarily

Answer 44

necessarily smaller than the pitch circles,

Question 45

The string is always

Answer 45

angent to the cylinder.

Question 46

The center of curvature of the involute is always at the

Answer 46

the point of tangency of the string with the cylinder.

Question 47

The contact point between the cylinders lies on the line of center

Answer 47

pitch point.

Question 48

reciprocal of the angular velocity ratio (mV)

Answer 48

torque ratio (mT)

Question 49

equal to the ratio of the radius of the input gear to that of the output gear.

Answer 49

angular velocity ratio (mV)

Question 50

equal to the ratio of the radius of the input gear to that of the output gear.

Answer 50

pinion and gear

Question 51

are ones in which the teeth are parallel to the axis of the gear. This

Answer 51

SPUR GEARS

Question 52

are ones in which the teeth are at a helix angle, Ψ, with respect to the axis of the gear

Answer 52

HELICAL GEARS

Question 53

They run quieter than spur gears because of the smoother and more gradual contact between their angled surfaces as the teeth come into mesh.

Answer 53

HELICAL GEARS

Question 54

are formed by joining two helical gears of identical pitch and diameter but of opposite hand on the same shaft. These

Answer 54

HERRINGBONE GEARS

Question 55

which has only one tooth wrapped continuously around its circumference a number of times, analogous to a screw thread.

Answer 55

Worm

Question 56

means that the worm gear teeth are wrapped around the worm.

Answer 56

Single enveloping

Question 57

resulting in an hourglass-shaped worm.

Answer 57

Double enveloping

Question 58

based on the rolling centrodes of a Grashof double-crank fourbar linkage.

Answer 58

Noncircular Gears

Question 59

If the teeth are angled with respect to the axis,

Answer 59

SPIRAL BEVEL GEARS

Question 60

If the teeth are angled with respect to the axis,

Answer 60

a spiral bevel gear

Question 61

bevel gears are based on

Answer 61

rolling cones

Question 62

rotary to linear motion conversion or vice versa. It

Answer 62

Rack and Pinion