different bearings 1

[majuba]

Good day

I am an elect. engineer who needs some help understanding bearings for motors.

What are the different bearings available, in particular what is the difference between roller bearings and white metal bearings and sleeve bearings?

What maintenance needs to be done on each of these?

What is a journal?

What would cause a rise in bearing temperature?


Thanks in advance.

 

[jmoritz]

Start here......

http://www.skf.com/portal/skf/home/solutions?contentId=000911

Briefly:

What are the different bearings available, in particular what is the difference between roller bearings and white metal bearings and sleeve bearings?
**********roller bearings have rollers as the rolling element, sleeve bearings have no rolling elements

What maintenance needs to be done on each of these?
**********most important: proper lubrication

What is a journal?
**********a shaft

What would cause a rise in bearing temperature?
**********speed, friction, process temperature, lubrication problems, failure.....

 

[Mendit]

You are starting from the gound up.

Bearings 2 types

Anti-friction and Sleeve
Ball bearings (conrad suitable for radial and small thrust loads)
Roller Bearing Suitable for radial loads only (no thrust)
Roller used in higher than normal radial loads ie Belt drive
Spherical roller bearings, suitable for high radial loads and some thrust load.
Angular contact bearings,
Double row Suitable for thrust loads in both directions and radial loads.
Single row, suitable for thrust in only one direction, can be mounted in pairs for greater thrust loads or thrust in both directions. Common on Vertical motors.
Taper roller bearings (Timken) not common on motors have low speed capability.
Spherical thrust bearings, Common on large slow speed vertical motors. Thrust load only.
Ball bearings can be either grease or oil lubricated

Sleeve Bearings
Sleeve bearings typically babbitt lined Low friction tin alloy. radial loading only (very minimal thrust)
Sleeve bearings have a greater ability to handle high speed
Many large motors of the 2 pole are fitted with sleeve bearings.
Plain sleeve bearing, a round shell (steel with babbitt overlay, Typically with rings for oiling.
Lemon bearings,
Sleeve bearing with a bore which has reduced vertical clearance, to improve stiffness.
Pressure dam bearing.
Sleeve bearing with a cavity in the no load zone to provide increased loading through hydraulic pump.
Radial Tilting pad sleeve bearings
The cadillac of sleeve bearings, can be designed and modified to fit any application, must be force lubricated
Tilting pad thrust bearings, able to handle high speed and thrust loads, must be force lubricated
Maintenance,
Ball bearings usaully grease lubricated, Check manual for details.
Oil lubricated (usually a bath) change every 12mo

Sleeve Bearings
Ring oiled change oil every 12 mo or less for hot and dusty areas.
Pressure fed bearing
recommend change in oil every 3 years or do oil analysis.

Journal, The portion of the rotor shaft prepared to fit the bearing, Must true, round and parallel.

Temperature rise,
Usually related to lack of lubrication
Increased load
Contamination
Speed too high for application.

Tip, If the bore of the bearing in MM x the Max RPM of the motor, is greater than 250,000. You will have problems with grease lubrication.

Hope this helps.

 

[electricpete]

great info. Why do you say radial tilting pads must be force lubricated? We have them in an oil bath.

 

[Mendit]

Radial tilt pads and force lube, the majority of radial tilt pad bearings are on high speed equipment, they typically operate at less than a standard bearing clearance.
They absorb more energy than conventional bearings thus creat more heat. Your application must be vertical shaft (some large motors are fitted this way) but their loading is light. Need more info contact me direct.