190303a Flashcards
Gear teeth may be parallel to one another or they may be tapered with one large end and one smaller end
True
A gear tooth can be subdivided into 4 Distinctive quadrants. Identify the names of each of those quadrants
Face
Flank
Toe
Heel
The gear pitch line is used to divide the following gear tooth areas
Face and flank
When 2 gears are in mesh, a gap is formed between the tip of one gear tooth and the root In the opposite gear. This gap is called the:
Clearance for lubricant
Explain why some angle drive gear sets may need to be timed
The gears have been lapped in this pattern and need to be timed to continue this specific relationship
Gears may operate together as direct drive assemblies. identify two other types of gear configuration and explain the type of speed and torques changes that would be expected between the input and output members
Reduction. Speed reduction torque increase
Overdrive speed increase torque reduction
If a simple gear set has a gear ratio of 4:1 explain which member is turning at 4 revolutions
Drive (input ) member is rotating at 4 revolutions and Driven (output) will be once
Which of the following gear ratios would be a reduction gear ratio?
a) 0.10:1
b) 1.00:1
c) 10.00:1
d) 1.00:2
c) 10.00:1
When installed between a drive and a driven gear, an idler gear affects speed and torque changes between the two gears
False
It will only change the direction of rotation
Explain the purpose of an idler gear
An Idler gear is used to change the direction of rotation of the driven gear to the same as the drive gear
Name and explain the tooth design used on 2 types of external gears
a) straight cut square gear Teeth cut inline with the mounting shaft
b) Helical gear. Teeth cut at angle to the mounting shaft
Identify one common gearset where internal gears may be used
Planetary gear sets
What is another name for a double helical gear?
Herringbone gears
Straight cut spur gears and helical gears both produce axial thrust loads during operation?
False
Identify the 3 main components of a simple planetary gear set
a) Internal gear or ring gear
b) Planet pinions
c) Sun gear
When describing wider gear teeth,what are the three sections across
Heel and toe separated by a center section
What does the term path of power mean
It’s used when describing or tracing any power flow such as from the engine flywheel to the drive axles
When gears are used in mobile equipment, such as a highway tractor the drive side gear has what shape?
The drive side is convex
On some gear designs, a concave shape will be used at what time in the powertrain?
When in coast mode. The loaded vehicle is pushing the powertrain
What are three gear circles
Root, pitch, and outside circles. Each measured across opposite sides of the gear
In order to determine circular gear pitch, what must be first established? And second?
The pitch circle. Then the distance between the gear tooth centerlines
Why do engineers create a space called backlash?
To allow for expansion during operation and allow for lubrication
If backlash is incorrect what may need to be adjusted
Gear mesh
Will a worn gear increase or decrease backlash?
It will increase and could cause timing issues. Such as crankshaft and camshaft operation
What are two gears used in angled drive gear sets
The smaller gear known as the pinion gear, and a larger crown, bevel or ring gear
Do hunting gear sets have to be timed?
No. The number of pinion teeth will not dividing to the crown teeth equally. Different tooth contact and no specific wear pattern
What does the addition of an idler gear and shaft assembly create between Drive and driven gears?
A rotational direction change. There will be no speed difference or change in torque
What’s the purpose of adjusting gear mesh?
To achieve a wear pattern that will provide maximum gear set life
What are the advantages of straight cut spur gears
Cheap manufacturing process, no axial thrust.
What are disadvantages of straight cut spur gears
Not high-strength units, noisy, load handling ability is limited
What’s a major advantage of helical gears?
Multiple teeth engage at one time reducing noise and increasing strength
What gear set changes rotary motion into linear motion?
Rack and pinion
Hypoid angle gears and Amboid gears have high load handling capability. What’s the difference between them?
Hypoid angle gears have the angle pinion gear below the centerline. Amboid gears is above centreline to allow a higher driveline position.
What application could you see a strong but expensive, worm and worm wheel gearset in
Hi torque load application such as winch drive
A planetary gear set needs a drive member, a driven member and a stationary or held member. What is another name for the stationary member?
The reactionary member
What are five various planetary gear set conditions?
Direct drive. Reverse Reduction Overdrive Neutral
