Bearings 2 Flashcards
What is the primary function of a bearing?
Bearings allow two parts, like a shaft and housing, to move freely relative to each other.
What are the two main types of bearings?
Plain Bearings (sliding motion) and Rolling Element Bearings (rolling motion).
What’s unique about Rolling Element Bearings?
They operate with rolling motion, allowing for higher speeds and loads compared to Plain Bearings.
Key characteristics of Rolling Element Bearings
Rolling motion, higher speed and load capacity, reduced friction and wear.
What types of loads can Rolling Element Bearings handle?
Radial and thrust loads, though specific capacity varies by design.
example of a common Rolling Element Bearing
Single Row Deep Groove Ball Bearing - Handles radial and some thrust loads, cannot take misalignment.
Cylindrical Roller Bearings
High radial load capacity, does not support thrust loads.
Taper Roller Bearing
Withstands thrust load in one direction, good radial load capacity.
Thrust Roller Bearing
Designed to withstand thrust loads only, comes in ball or roller types.
Needle Roller Bearing
Very small diameter, mainly for radial loads, low thrust load capacity.
Bearing Life Calculation
Factor in fatigue due to contact stresses; manufacturers provide statistical data on bearing life.
Basic Static Load Rating
Maximum radial load a bearing can handle when not rotating.
Basic Dynamic Load Rating
The constant radial load a bearing can withstand for 1 million revolutions.
Rated Life of a Bearing
Number of revolutions before fatigue cracking occurs.
Bearing Life Calculation Example
Consider factors like bearing type, load ratings, and operational speed to estimate life in hours.
Design considerations for Rolling Element Bearings
Consider installation, misalignment, thrust load orientation, lubrication, and material compatibility.
Plain Bearings vs. Rolling Element Bearings
Plain Bearings: smaller, cheaper, quieter, more shock-resistant. Rolling Bearings: lower friction, easier lubrication, higher load/speed capacity.
What are Seals in Bearings?
Components that keep lubrication in and contaminants out of bearings.
Types of Seals
Static Seals (e.g., O-rings, gaskets) and Dynamic Seals (for rotating shafts).
Characteristics of Dynamic Seals
Used in moderate to high-speed applications, manage leakage, varying materials and designs.
Features of O-Rings
O-Rings are simple, versatile seals used for static and low-speed dynamic applications. They are specified by internal diameter and cross-section.
Applications of O-Rings
O-Rings are widely used in various mechanical systems to prevent leaks, especially in static applications or where there is minimal relative motion.
Characteristics of Rotating Shaft Seals
These seals are designed for rotating shafts and are often radial lip seals. They are suitable for moderate shaft speeds and can handle temperatures up to 100°C.
Use of Reciprocating Shaft Seals
Reciprocating Shaft Seals, such as packings and piston rings, are used in applications with high temperature and low speed. They provide effective sealing by compression in the housing.
