gearing principles

Question 1

when a gear tooth has been divided length wise this line is called

Answer 1

pitch line

Question 2

what are the top and bottom sections on the gear tooth pitch line

Answer 2

upper is the face - lower is the flank

Question 3

when a gear tooth has a larger end and a narrow end they are called

Answer 3

large is the heel - narrow is the toe

Question 4

what part of the gear tooth profile is slightly rounded and gives the gear strength

Answer 4

the root fillet

Question 5

what is path of power

Answer 5

can be used to determine which gears are actually in use and delivering power through the power train at a specific time

Question 6

what is another name for the drive side of a gear

Answer 6

the convex side

Question 7

what is another name for the coast side of a gear

Answer 7

the concave side

Question 8

non-hunting gear sets

Answer 8

needs to be timed . will always be a whole number ratio 3:1 4:1 5:1 ect

Question 9

partial non hunting gear sets

Answer 9

needs to be timed . will always be a ratio that equates to two decimal spots 4.35:1 2.25:1 3.75:1 ect

Question 10

hunting gear sets

Answer 10

does not need to be timed . every tooth of the crown will come into contact with every tooth of the pinion . will be a run on decimal ratio 1.33333333:1 2.76555:1 ect

Question 11

what is direct drive

Answer 11

1:1 ratio two identical gear in mesh

Question 12

when two external gears are in mesh what happens to direction

Answer 12

they will be opposite of each other

Question 13

how do you calculate gear ratio on a simple gear set

Answer 13

driven over drive

Question 14

what is a gear reduction

Answer 14

small gear driving a larger gear . will always be > than 1

2:1 - 1.1:1 - 3:1 ect

Question 15

what is another name for a gear reduction

Answer 15

underdrive

Question 16

what is the relationship of speed and torque in a reduction gear set

Answer 16

speed decreases and torque increases

Question 17

what happens with direction of rotation when idlers are added to a gear set

Answer 17

odd number of idlers will rotate the driven and the drive gears the same direction . even number of idlers will rotate the drive and the driven gears opposite direction

Question 18

will adding idlers to a gear set change the overall speed and torque of the set

Answer 18

no they only affect direction of rotation

Question 19

what thrust loads do spur cut gears create in mesh

Answer 19

vertical . they will try to push each other apart vertically

Question 20

what thrust loads will helical gear sets create

Answer 20

axial thrust loads . they need to be used with thrust washers on either side of the gears

Question 21

why are spur cut gears used on heavy equipment

Answer 21

cheap to make and strong

Question 22

when an external gear is used with an internal gear what happens to direction of rotation

Answer 22

driven and drive will rotate the same direction

Question 23

what is an advantage of a double helical gear design

Answer 23

no thrust washers are needed because thrust loads are equalized on either side of the gears

Question 24

what gear set would be used to change rotary motion in gears to linear

Answer 24

rack and pinion

Question 25

what are some disadvantages to straight cut bevel gears

Answer 25

noisy and may be limited to low torque load applications

Question 26

in order to gain strength in design of angle gear sets

Answer 26

spiral gear sets can be used

Question 27

what is the purpose of the short stub shaft on spiral that extends past the end of the pinion gear

Answer 27

is supported by a bearing and helps keep the pinion and crown gear in mesh during sudden shock loads

Question 28

what is the advantage of a hypoid angle gears

Answer 28

can handle high torque loads due to its position on the crown gear . lower position on the crown centerline allows more pinion teeth to engage the crown

Question 29

what is the advantage of an amboid gears

Answer 29

pinion is set above the center line of the crown gear allowing for a higher driveline position for clearance

Question 30

what are some advantages to worm cut gears

Answer 30

can handle very high torque . and by design they can also act as a brake

Question 31

what type of gear set is often used when the input shaft and output shaft are operate on the same plane

Answer 31

planetary gear sets

Question 32

what are the three parts of a planetary gear set

Answer 32

the sun gear - the carrier gears or planetary - the internal gear

Question 33

what is the held member of a planetary gear set also called

Answer 33

reactionary member

Question 34

what is the acronym for planetary gear ratio calculations

Answer 34

P-I-O ( planetary input = overdrive )
P-O-R ( planetary output = reduction )
P-H-R ( planetary held = reverse )

Question 35

how do you get direct drive on a planetary gear set

Answer 35

any two members held - or driven at the same rpm in the same direction

Question 36

how do you get neutral on a planetary gear set

Answer 36

no members held