* Rolling bearing

 

1. Bearing

 1-1. Definition

    A bearing is a machine element that constrains relative motion to only the desired motion and reduces

    friction between moving parts. A shaft attached to the bearing is called a journal.

    Heat due to friction arises in the bearing part and power loss occurs.

 

 1-2. Classification (By the way of contact)

     (1) Sliding bearing : Sliding friction arises and an oil film is formed by the lubricant between

                                            the journal and bearing.

     (2) Rolling bearing : Rolling friction arises in the rolling elements.

 

 1-3. Sliding Bearing and Rolling Bearing

 

2. Rolling bearing

 2-1. Characteristics

     (1) Has low friction coefficient and emits little heat due to the nature of the rolling contact.

     (2) Convenient and easy to exchange due to its standardized size.

     (3) Causes noise and is vulnerable to external shock.

 

 2-2. Structure

     (1) Radial bearing

               → Consists of inner race, outer race, rolling element, retainer.

            1) Inner and outer race : A track that a rolling element rolls on. The inner race combines with the axis and 

                                                            the outer race combines with housing.

            2) Retainer : Also known as a cage, it partially covers the rolling element to prevent rolling elements from

                                     adjoining.

     (2) Thrust bearing

               → Consists of the inner ring washer, outer ring washer, rolling element, and separator.

            1) Inner and outer ring washer : A track that a rolling element rolls on. The inner ring washer combines with

                                                                        the axis and the outer ring washer combines with the housing.

            2) Separator : Keeps regular distance between rolling elements to prevent rolling elements from adjoining.

 

     (3) Contact angle

            1) The angle between the line that unites the point of contact of the inner, outer race and rolling element,

                   and the line perpendicular to the rotating axis

            2) Nominal contact angle : a contact angle without external force

                   - Radial bearing: nominal contact angle < 45˚

                   - Thrust bearing: nominal contact angle > 45˚

 

* Please refer to the attached file below.