6.8 Bearings✅(3) Flashcards
(35 cards)
A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts (T or F)
T
What are bearings in aircraft components designed to do
- produce minimum friction
- have maximium wear resistance
What are the 2 major groups of bearings?
- Plain bearings
- Roller bearings
The 2 groups can be further sub-divided into another 2 major categories which are?
- ball bearings
- roller bearings
What is a plain bearing
- no moving parts
What is a roller bearing
- has enclosed and hardened rolling components that roll in inner and outer cases
A good bearing has 2 characteristics
- strong material (move with minimum wear and friction)
- Provide quiet and efficient operation
What are axial/thrust loads
- acting along the supported shaft (pulling/pushing the shaft)
What are radial/journal loads
- acting at right angles to the shaft (e.g. vertical (hanging) weight on horizontal shaft
Can a bearing have a combination of both loads during operation?
Yes
What must bearings require to reach long service lives?
- adequate lubrication
What are synthetic bearings often lubricated with
water
The water in a synthetic bearings acts as a lubricant and what else
coolant
With sliding bearings, grease lubrication is usually only used for strongly stressed bearings (T or F)
T
What loads are plain bearings designed to take
radial loads (sometimes called journal loads)
Plain bearings are normally used where loads are relatively light and the motion is continuous (T or F)
T
Why have anti-friction bearings replaced plain bearings
Less maintenance required
Bearings for pivot journals, which are designed to accept forces in a longitudinal direction is called what
pivot bearings or axial bearings
What are the 5 types of anti-friction bearings
- Tapered
- Needle
- Ball
- Spherical (symmetrical & asymmetrical)
- Cylindrical
What does a anti-friction bearing consist of
- outer/inner raceway
- rolling element
- rolling element cage
What are the raceways and rolling elements manufactured from
- chromium steel
- chromium nickel steel
What materials are usually made for cages
-steel plate
- brass plate
Ball bearings have very low starting resistance and are suitable for high rotational speeds (T or F)
T
What are the major components of a standard ball bearing
- Outer ring/race
- Inner ring/race
- Rolling elements (balls in this case)
- Retainer
