Antifriction bearings

Rogalla ANTIFRICTION BEARINGS


 

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ANTIFRICTION BEARING SOLUTIONS

optimised for application and purpose

Antifriction bearings are what get the modern world moving. An industrialised society would not be possible or would not even have been able to develop in the first place, without the use of antifriction bearings, because the industrial production of goods would have been inconceivable.

The history of the antifriction bearing goes back a long way – archaeologists found small cylindrical pieces of wood near the wheel hubs of a chariot during excavations from the Celtic period. Like so much of human history, though, this was forgotten, and it was not until 1490 that Leonardo da Vinci drew the design of a ball bearing.

What we consider to be antifriction bearings today were developed in the late 19th century.


What are antifriction bearings?

Antifriction bearings are components in which the friction resulting from the rolling motion of two components moving relative to each other is reduced by rolling elements.
This operating principle essentially distinguishes antifriction bearings from plain bearings, in which parts moving against each other are in direct contact
with each other or are only separated by a lubricating film.

The main tasks of an antifriction bearing are as follows:


Transfer
Motion


Minimise
Friction


trasmit
Forces

The basic design of antifriction bearings

The basic design of an antifriction bearing is actually relatively simple and generally consists of the following components:

 

1. Outer ring

with integrated raceway for guiding the rolling elements


2. Inner ring

with integrated raceway for guiding the rolling elements


3. Rolling elements

(balls, rollers or needles)


4. CAge for mounting

and guiding the rolling elements in the raceways


Illustration shows a riveted sheet steel cage

The inner and outer rings as well as the rolling elements of an antifriction bearing are generally made from high-purity, chrome-alloyed antifriction bearing steels such as 100Cr6. There are also antifriction bearings made from corrosion-resistant steels, special materials such as ceramics (full ceramic bearings and hybrid bearings made from silicon nitride, silicon carbide or aluminium oxide) and plastics for use under special or extreme operating conditions.

The task of the cage is to hold and guide the rolling elements in the raceways. In the case of cages, various materials such as steel, brass and plastic (e.g. window cages made from fibreglass-reinforced polyamide) have also become established. The choice of cage materials depends on the designs, bearing type and requirements.


The shape of the rolling elements describes the principle of power transmission (point or line contact) and determines the name (e.g. ball bearing or roller bearing).


Since rolling motion also leads to rolling friction in antifriction bearings, adequate lubrication of the contact surfaces is vital. Lubrication performs many important tasks in this respect: it reduces friction as well as heat and noise generation and protects against corrosion and contamination. Lubrication also reduces wear. The necessary lubrication can be provided by oil lubrication in closed systems such as gearboxes or must be supplied from outside by relubrication. In addition to the open variants, there are also designs in sealed and lifetime-lubricated versions. The sealing washers and cover washers also protect the running surfaces of an antifriction bearing against contamination and foreign particles while at the same time preventing the lubricant from leaking.

Radial bearings and thrust bearings

The direction of the main load leads to a differentiation between the two basic forms, namely radial bearings and thrust bearings.
Both basic forms of antifriction bearings are available as ball bearings and roller bearings.


Radial bearings

absorb forces perpendicular to the shaft axis (radial).



Thrust bearings

absorb forces in the direction of the shaft axis (axial).


Ball bearings and roller bearings

The basic forms of antifriction bearings are divided into a further six groups:

  • Ball bearings (radial and thrust bearings)
  • Cylindrical roller bearings (radial and thrust bearings)

 

  • Needle roller bearings (radial AND thrust bearings)
  • Tapered roller bearings (radial and thrust bearings)
  • Spherical roller bearings (radial and thrust bearings)
  • Housing bearings (radial and thrust bearings)

While ball bearings are particularly suitable for fast-turning applications due to the point contact between the balls and the raceway, they are less suitable for high loads. This is where roller bearings are used, as the line contact between the rollers and the raceway allows them to support very high forces.

The correct choice of design therefore depends on the application

The right antifriction bearing for every application. The characteristic properties of the various types predetermine the respective design for specific areas of application and uses. When installed, antifriction bearings are functionally relevant machine elements, and the choice of the suitable antifriction bearing is the decisive factor for service life and durability.

In most cases, the size of the adjacent structure provides the framework for the size of the antifriction bearing or limits the dimensions. However, installation space and the direction of the main load alone are not sufficient for an optimal selection of the suitable antifriction bearing.

Antifriction bearings perform their work, most of which is invisible or imperceptible to the user, in electric motors, gearboxes, fans, pumps, compressors, household appliances, drills and powered tools, construction machinery, cars and rail vehicles, conveyor systems, wind turbines, chemical and petrochemical plants, agricultural engineering, food industry and beverage production, raw materials extraction, iron and steel industry, paper industry and pulp processing, cement mills, plastics production and film manufacture, medical technology, aerospace technology and robotics and automation technology, to name just a few applications and industrial sectors.

Important selection factors include:

  • Application / use
  • Installation situation (installation space) / adjacent structure
  • Operating conditions (speed, operating temperature, ambient conditions)
  • Type of lubrication (grease or oil)
  • Requirements on the service life / durability
  • Assembly, disassembly and maintenance

Today’s users have a wide range of standard antifriction bearings to choose from when looking for the right antifriction bearing for their particular application.

The antifriction bearing product range also includes:

Antifriction bearing accessories

Spherical plain bearings & rod end

Housing bearings & housing units

Types and designs


Radial ball bearings

  • Deep groove ball bearings
  • Deep groove ball bearings, single row
  • Deep groove ball bearings, double row
  • Hybrid bearings
  • Insulate
  • Corrotec
  • HighTemp
  • Xtreme
  • Angular contact ball bearings
  • Angular contact ball bearings, single row
  • Angular contact ball bearings, double row
  • Self-aligning ball bearings
  • Four-point bearings
  • Spindle bearings
  • Spindle units

Radial roller bearings

  • Spherical roller bearings
  • Spherical roller bearings, McGill Sphere Rol
  • Spherical roller bearings for vibrating screen machines
  • Cylindrical roller bearings
  • Cylindrical roller bearings, single row
  • Cylindrical roller bearings, double row
  • Cylindrical roller bearings, multiple row
  • Full-complement cylindrical roller bearings
  • Tapered roller bearings
  • Yoke-type rollers
  • Cam followers
  • Track rollers
  • Needle bearings
  • Special bearings

Thrust ball bearings

  • Thrust deep-groove ball bearings

Thrust roller bearings

  • Thrust spherical roller bearings
  • Thrust cylindrical roller bearings
  • Thrust tapered roller bearings
  • Tandem bearings

Antifriction bearing accessories

  • Clamping sleeves
  • Withdrawal sleeves
  • Locknuts and shaft nuts
  • Fuse plates

Housing bearings & housing units

  • Flange bearings
  • Flange bearing housing units
  • Pedestal bearings
  • Pedestal bearing housing units

Spherical plain bearings & rod ends

  • Radial spherical plain bearings
  • Thrust spherical plain bearings
  • Angular contact spherical plain bearings
  • Rod ends