Alb Mod Bearing Maint B Flashcards
The two most common methods of delivering oil to bearings is using: (2)
- Hydrodynamic lube
- Hydrostatic lube
Hydrodynamic lubrication uses ____ to deliver oil to bearings
velocity
The two common methods of delivering oil to a bearing for hydrodynamic lubrication is using: (2)
- Pump
- Slinger ring, splash
How does hydrodynamic lubrication compare to hydrostatic in regards to reserve capacity?
Hydrodynamic has more reserve capacity
A disadvantage of hydrodynamic bearing lubrication is the occurrence of ____ at higher speeds
oil whirl
Hydrostatic lubrication uses _____ instead of velocity to force the fluid film to the loaded area
pressure
a hydrostatically lubricated/hybrid bearing is vulnerable to:
Failure of the pressure supply
A hydrostatically lubricated bearing has a ___ load capacity than a hydrodynamic bearing of the same size
lower
To support a full load, hybrid lubrication requires both:
hydrodynamic lube in addition to hydrostatic
Both hydrostatic and hybrid bearings are fitted with:
restrictors, for oil
What lubrication method could you use for a large, unbalanced load at high speeds?
Hybrid
Hydrostatic bearings are best suited for:
slow speed, heavily loaded bearings
What bearing would you use when maximum loads occur only when hitting high speeds?
hybrid
Oil lift is produced by a hydrostatic supply of oil called:
jacking oil
Jacking oil produces enough force to:
lift the journal off the bearing
The surfaces of rolling elements are lubricated via an oil bath, splashing, oil jet or mist, and as the bearing rotates, a ____ is formed between the rolling element at each raceway
oil wedge
When lubricant is wedged between a race and a rolling element, the extreme pressure causes the lubricant to enter a _____ state
elasto-hydrodynamic
Two widely used air activated lube systems are: (2)
- oil mist
- air oil
an oil mist system uses a compressor to provide compressed air at 10 to __ psi to atomize the oil
50
Which system, oil mist or air oil, uses a vanturi?
oil mist
With an oil mist system, you can have 3 typed of nozzles for different degrees of condensation. Which would you use for high speed, anti friction bearings?
Mist nozzle
With an oil mist system, you can have 3 typed of nozzles for different degrees of condensation. Which would you use for chains, drives, gears, open bearings?
spray nozzle
With an oil mist system, you can have 3 typed of nozzles for different degrees of condensation. Which would you use for slow moving slides and machine toolways?
condenser nozzles
Air oil systems are used for:
medium to high speed anti friction bearings
A bearing should be packed with grease ____ it is mounted
after
What 3 parts may not be immediately obvious, and uncovered, on a rotating shaft? (3)
- Shaft key
- Flinger
- Set screws
Keeping a machine clean allows these benefits: (4)
- Allows for accurate inspection
- Better heat dissipation
- Keeps free of corrosives
- Reduces bearing contamination
It is important to inspect a machine while it is running because:
Noise, vibration, leaks are more easily detected
A sour smell to lubricant indicates:
Acid build up from oxidization
A change in oil colour indicates a:
breakdown in the lubricant
Be sure the breather for a bearing case is clear, and that the sight glass is not:
discoloured, giving a false “full”
Lubrication should be done when:
the machine is down
Pump grease into a bearing until clean grease is expelled from the:
outlet port
What is the first thing you should check when a bearing is running too hot?
oil level. Too high or too low.
Note: can also be caused by: external heat sources, breakdown of lube, degraded seals, alignment, incorrect clearances, or soft feet under housing
Vibration in a bearing can be caused by: (4)
- Alignment
- Bent shaft
- soft foot
- misaligned or damaged (flat spot) bearing ring
It is always important to check that a shaft can be turned:
by hand without anymore resistance than is normal
What are some reasons that a shaft cannot be turned by hand? (5)
- Seals too tight
- flinger is dragging
- fan on motor touching housing
- bent shaft
- insufficient clearance
When bearing noise becomes apparent, the bearing usually already has to be replaced within days or hours. Before this noise occurs, you will be able to detect a rise in:
temperature
How can a constant level cup be installed on a bearing assembly wrong?
Can be mounted on the wrong side, and can be mounted too high or too low.
