This document provides information on gears and gearboxes. It begins with definitions of basic gear terminology like driver gear, driven gear, idler gear, and gear ratio. It then describes different types of gears including spur gears, helical gears, bevel gears, and worm gears. The document also discusses gear trains, interference, gear nomenclature, backlash, lubrication methods, and symptoms of lubrication failure. Finally, it provides guidance on installing, mounting, and disassembling a gearbox.

1. A
PROJECT FILE
ON
GEARS AND GEAR BOX
SUBMITTED BY-
1. PRITAM KUMAR [ ME/19/63L]
2. SACHIN KUMAR THAKUR [ME/19/64L]

2. Basics of Gears

3. What is Gears
A gear is a wheel with teeth on its outer edge.
The teeth of one gear mesh (or engage) with the
teeth of another.
Above
Gears meshing or engaged

4. Driver and Driven
Two meshed gears always rotate in opposite directions.
Driver gear
Driven gear

5. Idler gear
Driver
Idler gear
Idler gear
Driven

6. • Generally, the Gear Ratio is calculated by
counting the teeth of the two gears, and
applying the following formula:
Gear Ratio
Gear ratio = Number of teeth on driven gear
Number of teeth on driver gear

7. Gear Ratio - Calculation
A 100 tooth gear drives a 25 tooth
gear. Calculate the gear ratio for
the meshing teeth.
Gear ratio = Number of teeth on driven gear
Number of teeth on driver gear
Gear ratio = driven 25 = 1
driver 100 4
This is written as 1:4

8. Type of Gears
• Spurs
• Helical
• Bevel
• Bevel
• And Worm Gears

9. Spur Gears
Are used in transmitting torque between parallel shafts

10. Helical Gears
Are used in transmitting torques between parallel or non parallel
shafts, they are not as noisy as spur gears

11. • Bevel gears are used to transfer drive through an angle
of 90o.
Bevel gears
Bevel Gears

12. • The worm gear is always the drive
gear
Worm gear and wheel
Worm and wheel

13. • The rack and pinion gear is
used to convert between rotary
and linear motion.
Rack and Pinion
Heavy Duty
Heavy Duty
Car Jack

14. • Multiple gears can be connected together to form a gear train.
Simple Gear Train
Gear train
Each shaft carries only
one gear wheel.
Intermediate gears are known
as Idler Gears.

15. Compound Gear Train
Driver
Compound
Gear
If two gear wheels are mounted on
a common shaft then it’s a
Compound Gear train.
Gear
Driven

16. Planetary Gear train
You can get high torque ratio in a smaller space
There are two inputs to the planetary gears, RPM of sun and Ring, The
out put is the speed of the arm.

17. INTERFERENCE
A minimum number of teeth are required on the
pinion to avoid interference.

18. NOMENCLATURE OF GEAR

19. NOMENCLATURE OF GEAR
 Addendum :The addendum is the height by which a tooth of a gear projects
beyond (outside for external, or inside for internal) the standard pitch circle or
pitch line; also, the radial distance between the pitch diameter and the outside
diameter.
 Addendum circle :The addendum circle coincides with the tops of
the teeth of a gear and is concentric with the standard (reference) pitch circle
and radially distant from it by the amount of the addendum. For external gears,
the addendum circle lies on the outside cylinder while on internal gears the
addendum circle lies on the internal cylinder.
 Circular Pitch : The Circular Pitch defines the width of one tooth and
one gap measured on an arc on the pitch circle; in other words, this is the
distance on the pitch circle from a point on one tooth to the corresponding
point on the adjacent tooth. This is equal to π divided by the Diametral Pitch.


20. NOMENCLATURE OF GEAR
 Pitch circle :A pitch circle (operating) is the curve of intersection of a
pitch surface of revolution and a plane of rotation. It is the imaginary circle
that rolls without slipping with a pitch circle of a mating gear. These are the
outlines of mating gears. Many important measurements are taken on and
from this circle.
 Clearance : Distance between the root circle of a gear and the
addendum circle of its mate.
 Working depth : Depth of engagement of two gears, that is, the sum of
their operating addendums.
 Dedendum : Radial distance from the depth of the tooth trough to the
pitch surface.
 Whole depth : The distance from the top of the tooth to the root; it is
equal to addendum plus dedendum or to working depth plus clearance.

21. What is Backlash ?
Backlash, a clearance between mating gear teeth, is built into speed reducers to
let the gears mesh without binding and to provide space for a film of lubricating
oil between the teeth. This prevents overheating and tooth damage.

22. BLUE MATCHING
• SPUR & BEVEL GEARS: IT IS DECIDED BY APPLYING BLUE
PASTE ON THE DRIVING GEARS GIVING IT SEVERAL ROTATION &
SEEING TO THE BLUE MARKS ON THE TEETH FACES OF THE
MESHING GEARS.
• INTERPRETATION: IT SHOULD COVER ALMOST 70 - 80% OF
TOOTH SURFACE.

23. a b c
d e f

24. BLUE MATCHING OF WORM GEARS
• APPLY BLUE PASTE ON WORM OF
THE GEAR BOX. IT SHOULD OCCUPY
ABOUT 60% OF THE AREA OF WORM
WHEEL.

25. BLUE MATCHING OF BEVEL GEARS
• BLUE MARK SHOULD OCCUPY
ABOUT 50% OF THE TOOTH FACES.

26. Types of gear lubrication

27. Lubrication selection method

28. Grease lubrication

29. Splash lubrication(oil bath method)

30. Force oil circulation

31. The purpose of lubricating gears

32. Symptoms of Lub Failure (Helical / Spur
Gear)
SN Symptoms Possible reason
1 Gear Profile Worn out Less / Wrong Lubricant
2 Blue / Black Marks
(High Temperature)
Less Lubricant
3 Scuffing / Spalling Lubricant / Load
Excessive
4 Oil Black Oxidised
5 Brown / Black Sludge Oxidised
6 Scoring Marks Solid Contaminants
7 Corrosion Water Ingress

33. Commonly bearing used for gear box
 Standard bearings – commonly used bearing types for
gearbox applications:
 Cylindrical roller bearings: Suitable for high radial loads
and High speed ratings
 Tapered roller bearings: Suitable for high radial loads
and thrust loads
 Angular contact ball bearings: Able to accommodate
both radial and thrust loads and Suitable for high speed
operation
 Deep groove ball bearing: Suitable for very high rotating
speeds Well suited for medium high radial and axial loads
in one or both directions
 Spherical roller bearing: spherical roller bearing is a
rolling-element bearing that permits rotation with low
friction, and permits angular misalignment

34. INSTALLATION OF GEAR BOX
 INSPECTION COVER & DRAIN PLUG ARE READILY
AVAILABLE.
 GEAR UNIT MUST BE MOUNTED ON LEVELLED
FOUNDATION USING THE CORRECT SIZE & TYPE OF
FOUDATION BOLTS.
 WHILE MOUNTING OVER HUNG PINIONS, GEARS OR
CHAIN SPROCKET CARE SHOULD BE TAKEN THAT AS FAR
AS POSSIBLE THE REACTION DUE TO CIRCUMFERENTIAL
FORCES IS DIRECTED DOWNWARD i.e. TOWARDS
FOUNDATION

35.  CHECK THE HORIZONTAL LEVEL BY MEANS OF LEVELLING
SEATS, CORRECT LEVELLING ENSURES PROPER
LUBRICATION OF THE BEARINGS.
 AFTER THE PROPER ALIGNMENT TIGHTEN THE
FOUNDATION BOLTS WITH TORQUE WRENCH TO
PREVENT OVER TIGHTENING . CHECK THE LEVEL AFTER
TIGHTENING OF THE BOLTS.
 WHILE GEAR BOX IS INSTALLED ON THE STRUCTURAL
FOUNDATION , CARE SHOOULD BE TAKEN THAT GEAR BOX
ARE MOUNTED ON COMBINED BASE FRAME WITH
DRIVING MOTOR & SUFFICIENT ACCESS SHOULD BE
THERE TO PROPERLY ALIGN THE INPUT & OUTPUT
COUPLING.

36. DISASSEMBLY OF GEAR BOX
 DECOUPLE THE GEAR BOX.
 REMOVAL OF BOLTS.
 REMOVAL OF COVER TO CHECK THE INTERNALS.
 REMOVAL OF COUPLING BY COUPLING PULLER.
 REMOVAL OF GEARS