7.12 Transmissions Flashcards
What is the primary function of a gear?
Transmission of power through motion
What are the common defects found during gear inspection?
- Cracks
- Chipped teeth
- Pitting
- Excessive wear
What maintenance action can be taken for minor scratches on gear surfaces?
Use a fine abrasive cloth
What is gear backlash?
The play between teeth in a gear system
What are the causes of gear failure or premature wear?
- Excessive backlash
- Poor lubrication
- Misalignment
What can cause corrosion in gears?
Exposure to corrosive conditions and moisture in the lubricant
What happens to gear teeth when lubrication breaks down?
Overheating occurs, leading to brittle teeth
What is overload wear?
Wear caused by heavy contact and sliding action between gear teeth
What causes pitting and spalling in gears?
Thin oil films and high temperatures
What causes cracking in gears?
Failure in heat treatment or improper machining
What is interference wear?
Wear caused by misalignment of gears
What is abrasive wear?
Wear from scratching and scoring due to particles in lubricant
What is a wear pattern in gear inspection?
Impressions left by one set of gear teeth on another set
How can the tooth contact pattern be established before final assembly?
Using Prussian blue
What is the function of backlash in gear systems?
Prevents gears from jamming and allows for lubricant space
What is the definition of minimum backlash?
Occurs when all tolerances give the shortest centre distance and thickest teeth
What is the formula for backlash variation?
Difference between maximum and minimum backlash in a gear rotation
How can backlash be measured in a gear train?
By locking one end and measuring limits of movement at the other end
True or False: Excessive backlash is always acceptable in gear systems.
False
Fill in the blank: The amount of backlash can be affected by changes in _______.
[centre distance]
What is the consequence of deep scratches or scoring on gears?
Not acceptable for continued use
What type of wear results in polished gear tooth surfaces?
Normal wear
What indicates impact overloading in gear breakage?
New metal over the break area