1. Discussion on Sliding Contact Bearing
(Types and working)
P r e s e n t e d B y
Name: Suraj Pakhira
Roll: 34900721066
Name: Asif Rahaman
Roll: 34900721068
Sub: Tribology ( PE - ME 802E )
Continuous Assessment 1
2. Introduction
Bearings are mechanical elements that allow relative motion
between two parts with minimal friction.
It does two function mainly a)supports the load acting on
the shaft, b) permit rotation of shaft with minimal friction.
Two main types: Sliding Contact Bearings & Rolling Contact
Bearings.
Sliding contact bearing : Operate on a thin film of lubrication,
without rolling elements..
3. Types of sliding
contact bearing
Based on
lubrication
Hydrodynamic
Bearings
Hydrostatic
Bearings
Boundary
Lubricated
Bearings
Dry Bearings
Based on Load
Direction:
Radial Bearings
(support radial
loads)
Thrust Bearings
(support axial
loads)
Based on
Material:
Metallic
Bearings
(Bronze, Babbitt,
etc.)
Non-Metallic
Bearings (PTFE,
Composite
materials)
Classification of Sliding Contact Bearings
4. Main Components:
Bearing Shell / Housing: Supports the bearing liner and
contains the lubrication system.
Bearing Liner: The inner surface that comes in contact with
the shaft, usually coated with low-friction material.
Lubrication Film: A crucial layer that separates the shaft from
the liner, reducing wear and heat generation.
Shaft: The rotating component that is supported by the
bearing.
Construction details:
5. Construction Details:
The bearing consists of a journal (shaft) and bearing housing with a clearance
filled with lubricant.
Depending on the type, the housing may have grooves for lubricant circulation.
The liner is made from materials with good wear resistance, such as Babbitt
alloy, Bronze, or PTFE.
Construction details:
6. Working
Principle:
Hydrodynamic Bearings:
When at rest, the shaft makes contact with the bearing surface.
As rotation starts, lubricant is drawn into the clearance space,
forming a wedge-shaped film.
This film builds pressure and lifts the shaft, preventing metal-to-
metal contact.
Hydrostatic Bearings:
An external pump supplies lubricant under pressure to separate the
shaft and bearing surface.
Ensures smooth operation even at low speeds.
7. Working
Principle:
Boundary Lubricated Bearings:
Operates under thin lubrication conditions where the surfaces have
partial contact.
Common in applications with intermittent motion.
Dry Bearings:
Made of self-lubricating materials like PTFE or composite materials.
Used in aerospace and high-temperature environments where
lubrication is difficult.
8. Hydrodynamic Lubrication Equation (Reynolds Equation):
Governs the pressure distribution in fluid film lubrication.
Derived from Navier-Stokes equation under assumptions of thin film
lubrication.
Reynolds Equation:
Petroff’s Equation for Coefficient of Friction:
Used for lightly loaded journal bearings where the shaft is concentric with the
bearing.
Formula:
Principles and Formula Derivation
9. • Automotive Industry: Engine bearings, crankshaft bearings.
• Heavy Machinery: Large turbines, compressors.
• Marine Industry: Ship propeller shafts.
• Aerospace: High-temperature applications with dry bearings.
• Machine Tools: Hydrostatic bearings in precision machines.
Applications of Sliding Contact Bearings
