ILM 190303 A

Question 1

When a Gear Tooth is viewed lengthwise, what are the upper and lower portions named?

Answer 1

The upper portion is the face, the lower portion is the flank.

Question 2

What is Gear Tooth Pitch Line?

Answer 2

The centreline that seperates the face and the flank.

Question 3

When a gear tooth has a large end and a narrow end, what are they called?

Answer 3

The large end is the heel, and the narrow end is the toe.

Question 4

What is the lowest portion of gear teeth, how is it shaped and what is it for?

Answer 4

The Root Fillet, this is rounded, and designed for strength.

Question 5

What is the highest portion of each gear tooth called?

Answer 5

The tip.

Question 6

When a gear is being driven, or is coasting, what is the shape of each side?

Answer 6

The drive side acts upon the convex side, whereas the coast or vehicle weight moving the gear acts on the concave side.

Question 7

What is the gear pitch circle?

Answer 7

Pitch Circle is a method for measuring the diameters of a gear.

Question 8

What is the circular gear pitch? How is it measured and what is it for?

Answer 8

This is the measurement, in degrees, from pitch circle centreline between two teeth. This is measured from the middle of the pitch circle at centreline. This provides the teeth the greatest amount of useable force.

Question 9

What is Clearance, and what is it for?

Answer 9

The space between teeth tip and root fillet, for oil lubrication.

Question 10

What is tooth backlash, and what is it for?

Answer 10

Backlash is a measured amount of clearance between gear faces to allow for expansion and lubrication.

Question 11

What is the difference between a Crown gear and a Pinion gear?

Answer 11

A pinion gear is typically the smaller, and a crown is larger.

Question 12

What is a Non Hunting Gear Set?

Answer 12

A Non Hunting gear set is one where crown and pinion will divide equally. 2:1, 3:1, 4:1. It is always timed.

Question 13

What is a Partial Non Hunting Gear Set?

Answer 13

A Partial Non Hunting gear set typically has more teeth on the crown gear, resulting in a 4.25:1, 4.5:1 ratio.

Question 14

What is a Hunting gear set?

Answer 14

This gear allows each gear to contact all teeth resulting in a offset gear ratio such as 1.33:1.

Question 15

What is the Formula for finding Gear Ratio

Answer 15

Driven/Drive

Question 16

What changes occur in a reduction gearset?

Answer 16

Slower speed output, with higher torque.

Question 17

What changes occur in an overdrive gearset?

Answer 17

Higher speed output, with lower torque.

Question 18

What is a Spur Gear, and what are some disadvantages and advantages? Where would you see it used?

Answer 18

A Spur Gear has straight cut teeth, they are cheaper to manufacture create no end thrust, but are louder. Used on things such as PTO’s

Question 19

What is a Single Helical Gear, some advantages and disadvantages? Where might these be used?

Answer 19

These are cut on an angle to increase strength and reduce noise. The angled teeth cause axial thrust requiring thrust bearings.

Question 20

What is a Hypoid angle gear?

Answer 20

Beveled helical cut gears, with the centreline of the crown located below the driveline.

Question 21

What is an Amboid gear? What is the importance of these in off road systems?

Answer 21

Beveled helical gears that have the centreline of the crown gear above the driveline. This is important because of higher ground clearance.

Question 22

What can cause a Direct Drive in a Planetary?

Answer 22

If two members are locked, or driven at the same rotational speed.

Question 23

What can cause a Reverse in a Planetary?

Answer 23

The Carrier being the held component, which causes the output to reverse.

Question 24

What can cause a Reduction in a Planetary?

Answer 24

When the carrier is the driven component, the result is always a reduction.

Question 25

What can cause an Overdrive in a Planetary?

Answer 25

When the Carrier is the drive component, this causes an overdrive.

Question 26

What can cause a Neutral condition in a Planetary?

Answer 26

No members held, everything just spins.