7.12 Transmissions Flashcards
1
Q
What is gear failure or premature wear caused by ?
A
- gear backlash
- poor lubrication
2
Q
When inspecting gears, what are you looking for?
A
- cracks, chipped teeth, excessive wear etc
3
Q
Types of gear wear?
A
- Overload wear
- Pitting & spalling
- Cracking and breakage
- Interference wear
- Abrasive wear
4
Q
What is overload wear?
A
- heavy contact causes lubricant to squeeze out and cause damage (e.g. burrs on tooth edge)
5
Q
What is pitting and spalling?
A
- thin oil films + high temp
- spalling is a fine crack (possibly caused by hardening)
6
Q
What is cracking and breakage?
A
- usually failure in the heat treatment
- or improper machining during manufacture
7
Q
What is interference wear?
A
- caused by misalignment of gears
8
Q
What is abrasive wear?
A
- caused by scratching and scoring
9
Q
What is gear backlash
A
- prevents gears from jamming
- amount of play they have
10
Q
What can you use to measure backlash in a gear train?
A
- using dial test indicator
- feeler gauge
11
Q
Why are chains inspected?
A
- check if chain has been stretched or worn
- check if chain passes smoothly over sprockets
12
Q
What does a sprocket do?
A
- convert rotary motion into linear motion (or vice versa)
13
Q
Does a worn sprocket cause rapid chain wear (T or F)? Should it be replaced?
A
- True
- must be replaced
14
Q
Explain drive belts?
A
- carry smaller loads than chain drives
- shock resistant
- quiet and smoother
- doesn’t require lubrication
15
Q
3 basic types of screw jacks?
A
- worm and peg
- worm and nut
- recirculating ball
16
Q
Explain worm and peg mechanism?
A
- excessive backlash which causes localised wear on the peg and worm screw
17
Q
Explain worm and nut mechanism?
A
- turning shaft to drive the nut
- by turning the nut to drive the shaft
18
Q
What is Recirculating Ball mechanism?
A
-
19
Q
When inspecting a screw jack arrangement what are the 2 primary maintenance concerns?
A
- Lubrication + backlash
20
Q
What are push-pull rods?
A
- adjustable lever devices (e.g. aileron and trim)
- transfer of compression (push) or tension (pull) forces
21
Q
What are bell cranks?
A
- transmit force or motion
- permit change in direction
