3. Energy Reduction Through Tribology
Red Sea University Faculty of Engineering Department of Mechanical Engineering
Energy Reduction Through
Tribology
Moataz Abdelgadir Ali Abdelgadir

4. What is tribology
Tribology embodies the study of friction, lubrication and wear.
and involves mechanical processes (motion and deformation).
A tribologist performs engineering work to predict and improve the performance (how much) and reliability (for how long) of a mechanical system.

5. Lubrication
Lubrication is used whenever two surfaces come into contact.
Lubricant serves two main purposes:
to reduce the friction when the two surfaces start or begin to move or slide over one onther
To cool the surfaces ( reducing heat losses)

6. Lubrication
Lubrication is used whenever two surfaces come into contact.
Other functions of the lubricant are :
to prevent corrosion
Remove contamination

7. Lubrication
Friction and wear studies estimate that up to 30% of consumed energy is exhausted in trying to overcome friction
Effective lubrication practice provide significant opportunities to reduce energy losses
In 1986, The NRC obtained 7.5% electrical energy saving through the immediate reduction fictional losses by using effective lubrication

8. The fundamental questions
Fundamental questions to be asked & answered by engineers are:
What causes a lubricant to lubricate?
What conditions must be fulfilled to fully separate two loaded surfaces in relative motion?
How can we manipulate these conditions in order to minimize friction and wear?
Is there only one or are there several mechanisms of lubrication?
In what specific applications do they operate?
What factors determine the classification of a load-carrying mechanism to a specific category?
How do thrust and journal bearings operate?
How can the design parameters for such bearings be estimated?
How does cavitation or oil whirl affect bearing performance?

9. Classification and types
of power transmission
units

10. Hydrodynamics bearings
Hydrostatic bearings

11. Hydrodynamic power transmission
unit

12. Hydrodynamic Lubrication
Hydrodynamic Lubrication is formed basically due to the dynamic motion or action of the moving parts. When sufficient quantity of lubricant is present between two surfaces in which at least one surface tends to move, the relative velocity of the moving surfaces tends to pump the lubricant between the two surfaces separating the two surfaces by a dynamic film of the lubricant.

13. Principle of hydrodynamic pressure generation between non-parallel surfaces

14. Elements of HD Bearing 1. The rotating member - Shaft
A typical hydrodynamic bearing consists of the following:
1. The rotating member - Shaft
2. The supporting bearing – Outer Sleeve
3. Lubricant
one way surge tank

15. 1- Working Principle
Before the shaft starts to rotate, both the shaft and the outer sleeve are in contact due to the self weight as shown below in the figure.

16. 2- Working Principle
As the shaft tends to rotate the lubricant in between the shaft and the sleeve tends to get squeezed and ultimately forms a boundary lubrication between the shaft and the sleeve but still a slight amount of metal to metal contact remains as shown in the figure.

17. 3 - Working Principle
As the shaft tends to rotate rapidly, the fluid lubricant is pumped by the shaft. The lubricant surface near to the shaft has a velocity which differs from the surface velocity of the oil surface near the sleeve. This causes a pumping action in the lubricant. The pumped lubricant ensures that the shaft and the sleeve remain out of contact. This phenomenon of the lubricant pumping itself to keeps two mating surfaces out of contact is termed as “Hydrodynamic Lubrication” and hence the name “Hydrodynamic Bearing”.

18. Working Principle

19. Hydrostatic lubrication

20. Introduction
In hydrostatic lubrication the bearing surfaces are fully separated by a lubricating film of liquid or gas forced between the surfaces by an external pressure. The pressure is generated by an external pump instead of by viscous drag as is the case with hydrodynamic lubrication

22. Flat circular pad bearing with a central recess.