2. Basically, the performance of a pair of
gears can be assessed by the measure of
success achieved in providing a positive
drive, while operating at the requisite
speeds, transmitting the maximum
designated power
3. Main points
Performance parameters
The failure forms of gear
Failure reasons
Lubrication of gears
Lubrication methods
4. Main points
Performance parameters
The failure forms of gear
Failure reasons
Lubrication of gears
Lubrication methods
5. Performance parameters
strength - life and durability
noise level - smoothness in operation
efficiency - operating temperature
size and weight of transmission
cost of manufacture - materials,
machining, heat treatment and assembly
running costs
6. Main points
Performance parameters
The failure forms of gear
Failure reasons
Lubrication of gears
Lubrication methods
7. The failure gear one of two forms:
The failure gear one of two forms:
A. complete fracture of the gear tooth; this
usually occurs at the root of the tooth
B. damage or destruction of the working
surfaces of the gear tooth
Either of these forms of failure may be the
result of one or a combination of any of the
following factors:
8. Main points
Performance parameters
The failure forms of gear
Failure reasons
Lubrication of gears
Lubrication methods
9. Failure reasons
failure may be the result of one or a
combination of any of the following
factors:
1. Initial stresses.
2. Poor tooth design.
3. Use of an incorrect material.
4. A material defect.
10. Failure reasons
5. Incorrect heat treatment for the selected
material.
6. Poor mounting and casing design.
7. Surface damage in final machining or
grinding operation.
8. Excessive operating temperatures.
11. Main points
Performance parameters
The failure forms of gear
Failure reasons
Lubrication of gears
Lubrication methods
12. Lubrication of gears
Up to a few years ago the engineering
world in general paid little or no attention
to the gearbox lubrication system during
the initial design stages.
Thus when the internal running gear was
finalized, lubrication became a major
problem when the design of the gearbox
casing commenced.
13. Lubricants used for:
Lubricants used for:
Reduce friction coefficient between
gears
Remove the dissipation heat
Protectbearings &gears against external
pollutants
14. Main points
Performance parameters
The failure forms of gear
Failure reasons
Lubrication of gears
Lubrication methods
15. Lubrication methods
1) Hand lubrication -where the lubricant is
applied from an oil can or similar type of
container.
2 ) Drip-feed lubrication - where the
lubricant is applied from an oil container
by means of a wick or a restricted oil feed
pipe.
16. Lubrication methods
3) Bath-type lubrication or, as it is more
commonly known, ‘splash lubrication’ where
the gear teeth are used as paddles to
circulate the lubricant.
4) Pressure lubrication - where the lubricant is
circulated by one of the various types of oil
pump through oil galleries or oil pipes to oil
jets which are directed at the gear.
