Flashcards in Bearings Deck (65)
Name four functions of a bearing lubricant.
It reduces friction
Reduces rust and oxidation
Seals out impurities
What are the three main functions of bearings?
Aid in Alignment
What are five of the criteria in selecting a bearing lubricant?
Size and type of bearing
How the lubricant is applied
Environment including temperature, exposure to water or chemicals
What are two types of sliding type (plain) bearing?
Split ( solid split, half, multi-part)
List three design features incorporated into sliding bearings to aid lubrication.
What are five desirable characteristics of a journal bearing lubricant?
It must: Maintain a full fluid film
Prevent excessive friction
Remain stable under severe operating conditions
The orientation of oil grooves in fluid-film journal bearings falls into two main categories. What are they?
Circumferential and axial
Channels are placed ______ _____ _____ _____ _____ in order to maintain the load carrying ability of plain bearings.
Away from the load zone
What are three advantages that plain bearings have over anti-friction bearings?
Easy to install
Carry high loads
Less sensitive to particle and water contamination
What are three advantages that anti-friction bearings have over plain bearings?
They may be sealed for life
can be used for high speeds
can accommodate misalignment
lower energy consumption
Where would anti-friction bearings be used where plain bearings would not be used?
What is a Kingsbury thrust bearing?
A bearing with tilted shoes that form an oil wedge between the shoe and the collar.
What are five types of rolling element bearings?
Cylindrical roll bearings
Thrust or tapered roll bearings
Spherical roll bearings
Needle Roll bearings
Deep groove Conrad
Name five parts of a rolling element bearing.
Cup (Outer ring)
Cone (Inner ring)
What are the five dimensions of a rolling element bearing?
Outside diameter (OD)
Inside diameter (ID)
Where there are two anti-friction bearings on a shaft, one should be ________ and the other should be _______.
Fixed ( or held )
Floating ( or loose )
What are the relative strengths and weaknesses of ball versus roller bearings?
Ball bearings are less expensive and can operate at higher speeds. Roller bearings carry higher loads.
Approximately what percentage of bearings fail prematurely?
What are six causes of failures in babbitted bearings?
Inadequate bonding of babbitt to sleeve
Incorrect oil grooving
Lack of lubrication
Loose bearing fastenings
What causes the eventual failure of a well-installed and lubricated anti-friction bearing?
What is False Brinelling?
The indentations in a race that formed by vibration, i.e. when bearings are in transit stored near vibration
What is Brinelling?
When a bearing race is marred by balls or rollers due to shock impact, often during handling and installation.
__________ Brinell and above have a tendency to show destructive pitting (spalling).
What is spalling?
Spalling (destructive pitting) results when normal loading is combined with sliding. It occurs when large wear particles are generated from subsurface cracks that are propagated from surface defects.
A sintered (also called porous or impregnated) metal bearing can contain up to ____% liquid lubricant impregnated between the metal pores.
Various means are used to lubricate large bearings. What physical characteristics are incorporated into bearing assemblies to assure adequate lubrication?
What does a lubrication chain do in a bearing assembly?
It is a chain that is used to pick up lubricant from the sump and deposit it on the bearing.
What is a bearing shield?
A metal disc fitted to the bearing outer ring with a small clearance with the inner ring.
What are the advantages of a chamfered oil groove in a bearing?
It prevents oil from being scraped off.
It promotes cooling
Greater flow and better distribution of oil to the bearing
It is rounding of the edges