7.12 Transmition Flashcards
What are advantages of using chains?
Flexible, positive connections, change direction
Where may chains be found?
Control column installations, aileron and elevator controls, trim control systems
What can chains be used in conjunction with?
Cables
What does a roller chain consist of? (Parts)
Outer and inner plates, rollers, bearing pins, bushes
What are the 3 roller chain principle dimensions?
Pitch, width between inner plates, roller diameter
Describe chain assemblies in terms of lubrication when you buy them
Come pre lubricated and shouldn’t be removed
What should you check for after installing a chain?
Twists and alignment with socket
How do you prevent backlash when installing a chain
Ensure they are not over or under tensioned
How do you prevent a chain from reversing?
Use a non reversible chain
How are non reversible chains different to normal chains?
Every second outer plate is extended to break the symmetry
What are the 4 parts of inspecting a chain?
General, removal, checking articulation, check for deterioration
How do you protect and store a chain?
Soaked and appropriately oiled, time allowed for lubricant to penetrate surface, wrapped in grease proof paper
What is a spur gear?
Most common, teeth perpendicular to face
What is a helical gear?
Teeth at angle to shaft, similar to spur gears
What is a bevel gear?
Transfer power between intersecting shafts and uses for any angle up to 180
What are hypoid gears?
Similar to bevel gears, teeth are hyperboloid shape
What are worm gears?
Resemble screws, can drive spur or helical gears
How do you prevent corrosion on gears?
Lubricant
If a gear cracks what happens to it?
It’s replaced
What is erosion caused by and how will it affect the gear?
Caused by cavitation, will effect gear over long period, will require replacement
What can affect backlash?
Change in distance, change in thickness, change in temperature
What is backlash?
The play between mating teeth.
Define minimum backlash.
Tolerances have shortest centre distance, thickest teeth at highest point
Define maximum backlash.
When Tolerances have greatest centre distance, thinnest teeth at lowest point
What is backlash tolerance?
Allowable amount of backlash
What is backlash variation?
Different between minimum and maximum backlash
What is the purpose of backlash?
Prevent gears jamming and making contact on both sides of the teeth at the same time
What can the amount of backlash be affected by
Changes in centre distances
Variance in tooth thickness
Temperature ranges
What is most commonly used gear
Spur gear
What are bi planet blocks
Changing the direction plane of the chain
What’s the advantage of worm gears
Mechanical advantage
Much larger step down between drive and driven shaft speeds where space is limited
