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Rolling contact bearing

https://www.growmechanical.com/2020/07/rolling-contact-bearing.html

Learning Objective of this chapter

  • Explained the different combination of bearing
  • Decrease the internal clearance and pre-load of bearing
  • Learn about bearing codes

Interview question on bearing

COMBINATION OF BEARING USE IN EQUIPMENT

Three type of combination of bearing mentioned below

  • O type of arrangement (DB) back to back
  • X type of arrangement (DF) face to face
  • Tendon arrangement

O type of arrangement (Back to Back)

The distance or (pressure point) between inner and outer cage is more because the smaller deformation occur due to moment loads this type of arrangement bearing can take large moment load than X type of arrangement.
Two angular contact ball bearing or two taper rollers bearing which take combine loads and can be paired in combination of X arrangement, O arrangement and tendon arrangements. O arrangement two bearing use for directional and axial load

X type of arrangement (Face to Face)

X type of arrangement use if the shaft going hot during the operation, to prevent bearing damaged from this pre-load given during mounting of bearing on shaft increases.
But in O type of arrangement the co-efficient of thermal expansion for bearing and other part will be same. Because the axial and radial thermal expansions cancel out each other, and in this condition given pre-load during installation does not change.

X type of arrangement bearing can tolerate the inaccuracy of housing and it can tolerate shaft deflection due to poor shaft rigidity.
Tandem arrangement use for heavy loads with low speeds.

What is cage bearing and full complement bearing?

full complement bearing

Full complement without cage bearing have a greater number of rolling elements. It can support very large loads. But mutual contact of rolling elements increases friction to each other. It is run at relatively low speed or to slewing motions.

Caged bearing

Caged bearing has smaller number of rolling elements. It can support less loads as compared to full complement bearing. But in caged bearing mutual contact of rolling elements have less friction to each other, rolling element are separate in it. It can run high at speeds.

Where full complement bearing are used?

High load with very low speed.

Types of Bearing internal clearance

Zero operational clearance and slight pre-load, some positive clearance, arrangement has some pre-load.

What happen if clearance is less than required in a spherical roller bearing after mounting on the shaft?

Bearing life reduced and creating noise during operation due to thermal expansion. What do you mean of bearing pre-load.

why it is important?

  • Enhance the bearing stiffness
  • Enhance the accuracy of shaft guidance
  • Compensate for wear and settling in operation
  • Give a long service life

Radial load

 

Cylindrical roller Double row angular contact Deep grove

List of Axial load bear bearing

Single row angular contact,  Taper roller bearing,  Deep groove.

Rolling contact bearing materials is that silicon Nitrite, 52100 steel, 440c stainless steel, m 50 steel.

Question

Most of ball bearing are made of ?

A) 20MC5, B) SAE2100, C) Silicon Nitrite, D) 440c stainless steel.
 

axial and radial force

 

Code for bearing

Bearing code are combination of three term (letter and number), that is prefix, basic code, suffix.

Prefix

There are 4 different prefixes use in bearing nomenclature,
R means ring of cylindrical or taper roller bearing with rolling element and cage but not separable ring.
WS means ring and ball of thrust ball bearing.
GS means housing washer of thrust ball bearing.
K means cage with rolling elements. Go for code of bearings.



 

Suffix

E high capacity bearing,
UA, UO AND UL means universal design of single row angular contact ball bearing with closed axial preload, no clearance and light preload respectively.
ZR and 2ZR bearing with one or two shields.
RSR and 2RSR bearing with one or two shields,
J, Y, M, F, L, T and TV pressed steel, pressed brass, machined brass, machined light alloy and plastic cage.
K means bearing with taper bore, taper 1:12 ratio.
PN (PO), P6, P5, P4, P2 tolerance class.
C1, C2, CN(CN), C3, C4, C5 bearing clearance.

For know, about inside bore, multiply last two digit with 5, and if D = 10, 12, 15, 17 then code number will be 00, 01, 02, 03 respectively.
And if d is more then 480 mm then written directly on bearings.

Full bearing code description with example 22320K EJ W 33 C33 C3 Means spherical roller bearing, straight bore, clearance is more then normal clearance, bore diameter is 120 mm, machined brass cage, high capacity bearing.

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