190303a gearing principals

Question 1

what does the pitch line divide?

Answer 1

Face and flank

Question 2

What is the face and flank?

Answer 2

Face is the top portion of the gear tooth, flank is the lower portion

Question 3

What is the heel and toe of a gear tooth? and what is it divided by?

Answer 3

The heel is the larger outer portion of the gear tooth, the toe is the inner portion, divided by the center of the tooth

Question 4

What is the root fillet of the gear tooth?

Answer 4

The root fillet is a slightly rounded portion of the bottom of the gear tooth to add strength

Question 5

What is the drive and driven side of the gear tooth? and what shape profile are both of those sides?

Answer 5

The drive side is the convex side, and the driven is the concave. concave is “caved” in and convex is “bubbled out” slightly

Question 6

when you decelerate the machine (or take your foot off the pedal, what happens?

Answer 6

The machine starts to coast and the vehicle pushes the powertrain through the concave or coast side of the gears

Question 7

What do two gear teeth have to have to be in mesh?

Answer 7

The same pitch. And the pitch circles have to be the same

Question 8

What is the pitch circle? and what makes up its measurements

Answer 8

it is a gears different measurements, and they are from bottom to top: root, pitch (middle of gear) outside measurements

Question 9

What is the circular gear pitch?

Answer 9

the measurement between the centerline of two gear teeth

Question 10

What is clearance pertaining to gearing?

Answer 10

the small gap that allows a lubrication film between the teeth as they mesh together

Question 11

What is backlash pertaining to gearing?

Answer 11

it helps with lubrication, and expansion of the gears.

Question 12

Why would you NOT set the backlash of a gear back to specifications on a WORN gear (if you replaced one but not the other)

Answer 12

if you brought the new gear closer to the bottom of the tooth, the worn out portion of the old gear would cause damage, thus your better to keep the old gearing pattern so as to not introduce metal to the gear case

Question 13

What is a non-hunting gear set and what would its ratio look like?

Answer 13

A non hunting gear set is a timed gearset, that has a specific gear pattern created, its ratio would be 3:1 as an example (a number divided into the crown gear equally)

Question 14

What is a partial non-hunting gear set, and what would its ratio look like?

Answer 14

A partially timed gear set, every 2 or 3 complete revolutions before it restarts its gear pattern, it is still a gear pattern, : 2 decimal places = partial non hunting ratio of 4.50:1 or 4:25, or 4.75, 4.30:1 : a number completing it one or two decimal places

Question 15

What is a hunting gear set and what does its ratio look like?

Answer 15

A hunting gear set is not timed, every pinion tooth will mesh with each and every crown gear tooth at some time during operation: its ratio is unequal numbers such as 4.123:1, or 5.267:1

Question 16

Explain the differences in gear ratio inputs and outputs (what a small gear driving a large gear does : there are 3 combinations)?

Answer 16

A smaller gear driving a larger gear is a reduction, A larger gear driving a smaller gear is an overdrive, and two gears the same size is a direct drive

Question 17

What is the purpose of an idler gear, and will it effect gear ratios?

Answer 17

To reverse the direction of gear rotation, no it will not effect ratio calculations “it freewheels”

Question 18

What are the types of gears available (there are lots)?

Answer 18

Straight cut spur gears, single helical cut gears, double helical cut gears (herringbone type), tapered gear teeth, external cut gears, internal cut gears, rack and pinion type gear sets (which can be both helical and straight cut), angle drive gear sets, bevel gears, spiral gear sets, amboid gear sets, hypoid gear sets, planetary gear sets

Question 19

What kind of thrust do straight cut gears create when in mesh?

Answer 19

Radial thrust

Question 20

What kind of thrust does a helical gear set create, when in mesh? and what controls the thrust?

Answer 20

Axial thrust, pushing each other in either direction, thrust washers or tapered roller bearings

Question 21

what direction does taper roller bearings control thrust (axial loads)

Answer 21

with the taper facing outwards away from the trust load

Question 22

What is an internal gear, and can it drive another internal gear?

Answer 22

an internal gear has its teeth cut facing the inner perimeter of the gear, and no it cannot drive another internal gear, a external gear can drive an internal gear

Question 23

an internal gear will rotate the same direction as a external gear driving it, true or false?

Answer 23

True

Question 24

What gears are commonly used due to their lower cost?

Answer 24

Straight cut spur gears

Question 25

Which gear has more teeth in contact : helical or straight cut gear sets?

Answer 25

Helical gear sets

Question 26

What position is a spiral gear in relation to the crown gear?

Answer 26

middle of the crown gear

Question 27

What position is a hypoid gear set, and what type of oil is required when hypoid gear sets are used?

Answer 27

below the crown gear center line, it uses EP (extreme pressure) type of lubricant due to the extreme pressures exerted on it.

Question 28

What position is an Amboid gear set and can it have the drive side on the concave side of the gear?

Answer 28

above the centerline of the crown gear, and yes it can have the drive side on the concave side of the gear.

Question 29

What are the advantages of a worm and wheel drive gear set?

Answer 29

High torque, fine movement, load cannot push the gearset back (holds gear in place)

Question 30

What is the condition of a planetary gear set when the carrier is held?

Answer 30

A reverse condition is created,

Question 31

What is the condition of a planetary gear set when the output is the carrier?

Answer 31

a reduction is created

Question 32

What is the condition of a planetary gear set when the input is the carrier?

Answer 32

an overdrive is created

Question 33

What is the condition of a planetary gear set when no members are held?

Answer 33

neutral condition is created