Gearbox Troubleshooting, Inspection & Maintenance.pptx

1. Gearbox Troubleshooting,
Inspection & Maintenance

2. Machinery Maintenance Practices Overview
Key Differences Between Gearboxes & Gearmotor's
Gear System Basics Functionality and Operation
Gear System Classification
Troubleshooting & Inspection & Maintenance
Program Content :-

3. Gearbox
Gearmotor
What is it? A box full of gears.
A motor with a gearbox
attached.
What does it do?
Slows down speed and
increases force
(torque).
Does the same thing,
but it’s all in one unit.
Where is it used?
Anywhere you need to
control speed and force.
Anywhere you need a
motor with built-in
speed and force control.

4. Gearbox

5. Gearmotor

6. Feature Spur Gear Helical Gear
Teeth Orientation
The teeth are parallel to the axis
of the gear1.
Teeth are inclined at an angle
(called helix angle) with the gear
axis1.
Load on Bearings
Imposes only radial load on
bearings1.
Imposes both radial and axial
loads on bearings1.
Noise and Vibration
Teeth of mating gears come in
sudden contact causing vibration
and noise12.
Teeth come in contact gradually,
resulting in smoother and quieter
operation23.
Load Carrying Capacity
Lower compared to helical
gears34.
Higher due to the gradual
engagement of teeth34.
Applications
Suitable for power transmission
over small distance1. Used in
devices like washing machines,
screwdrivers, windup alarm
clocks2.
Used for high-speed
transmission4. Commonly used in
transmissions2

7. Spur Gear

8. Helical-Gears

10. Worm Gear
Screw Gear
Motion Transfer
Converts rotary motion into rotary
motion with a gear ratio
Converts rotary motion into linear
motion
Interface
Power is transmitted through
sliding between the flanks of the
worm and the worm gear
Has a point-shaped flank contact
Gear Ratio
Can have a very high gear ratio,
especially when a single start
worm (one spiral) is used
Depends on the lead of the screw
Back-Driving
Generally not back-drivable,
meaning the output cannot drive
the input
Can be back-driven depending on
the lead angle and the friction
between the threads

11. Worm Gears

12. Screw Gears

13. The fact that worm gears are not easily back-driven is actually an advantage in many
applications. In the case of motor valve control, it means that once the valve is set to a certain
position, it will stay there unless the motor itself turns the worm gear. This prevents the valve
from being accidentally moved due to back-driving.

14. Term Description
Gear Train
A series of two or more gears used to transmit power from one shaft to
another1.
Gear Ratio
The ratio of the number of teeth of the driven or output gear and the
driver or input gear1. It is used to calculate the speed and torque of the
output shaft when input and output shafts are connected using a gear
train1.
Driver Gear The gear where we apply the torque1.
Driven Gear The gear where we use the applied torque1.
Idler Gears The gears used in between the driver and driven gears1.
Output Shaft Speed Calculated as Speed of input Shaft / Gear Ratio1.
Output Torque Calculated by multiplying the input torque with the gear ratio1.

15. A SIMPLE NUMERICAL EXAMPLE
• Suppose we have a gear train with an input gear (driver) with 10 teeth and an output gear (driven)
with 50 teeth. The input gear is rotating at a speed of 100 RPM and has a torque of 10 N-m.
1.Gear Ratio Calculation: The gear ratio is the ratio of the number of teeth of the driven gear to the
driver gear. So, in this case, the gear ratio (GR) would be 50/10 = 51.
2.Output Shaft Speed Calculation: The speed of the output shaft is calculated as the speed of the
input shaft divided by the gear ratio. So, the output shaft speed would be 100/5 = 20 RPM1.
3.Output Torque Calculation: The output torque is calculated by multiplying the input torque with
the gear ratio. So, the output torque would be 5 * 10 = 50 N-m1

16. Torque (τ)
Speed (ω)
Torque (τ) = Power / Speed (ω)

17. Driven
Driver
GR= Driven / Driver

19. Gear
Ratio
Speed
(ω)

20. • Gear arrangements refer to how the gears are positioned in a gearbox.
• There are three common types of gear arrangements:
• a. Parallel: Gears are positioned parallel to each other on separate shafts,
allowing power transmission between parallel shafts.
• b. Series: Gears are positioned in a series, with each gear rotating on a
different shaft, enabling power transmission between non-parallel shafts.
• c. Planetary: Gears are arranged in a system where a central gear, called
the sun gear, meshes with multiple outer gears, called planet gears, which,
in turn, mesh with an internal gear, called the ring gear. This arrangement
allows for high gear reduction ratios and compact designs.
Gear Arrangements

21. Planetary Gears

22. Parallel Gears

25. In Put
Shaft
Impeller Stator Turbine Sun
Internal
Gear
Out Put
Shaft

35. ECM/ECU
Brake Band
Clutch Packs
Solenoid
Control
Pump
Oil Pan

39. Thermographs
Infrared Energy
Emitted
Transmitted
Reflected

40. Tribology
Wear
Friction
Lubrication

41. Ferrography
wear particles a microscopic
examination and analysis

42. lube oil analysis
contamination.
Acid
overheating
oxidizing

43. Vibration
Temperature
Pressure
Flow
Current
Detection of machine faults Parameters

44. Why Do We Prefer Vibration Monitoring As a PdM Technique?
• Vibration data can help us identify faults or detect warning signs of
potential failures. It can also aid in the detection of misalignment or
unbalance of assets such as bearings and rotating pieces of equipment.
• Vibrations generally had two influences: first, particles reached a higher
average temperature, and second, they attained more uniform temperature
distribution. The particles average temperature generally increased by
increasing vibration amplitude and frequency
• The effect of the flowing fluid is to reduce the frequencies of vibration and
to increase the damping when the flow velocity is low. As the flow velocity
increases, some roots cross the real axis and the system loses stability by
flutter.

45. Technique Description Example
Time Domain Analysis
This method analyzes the amplitude and phase
information of the vibration time signal to detect faults in
the gear-rotor bearing system.
For example, if a gear tooth is damaged, the vibration signal will
show a spike every time the damaged tooth engages.
Resonance Analysis
This type of analysis is performed for identification of
natural vibrations and frequencies in a gear. Resonance
analysis may be conducted through techniques including
impact tests, recording of the run-up, and coast-down
curve, as well as measurement of the bending lines on the
shaft.
For instance, if a gearbox has a natural frequency that matches the
rotational speed of the gear, it can lead to resonance, causing
excessive vibrations and potential damage.
Frequency Domain Analysis
These methods include Fast Fourier Transform (FFT),
Hilbert Transform Method, as well as Power Cepstrum
Analysis. They are used to analyze the frequency content
of the vibration signals.
For example, FFT can be used to identify specific frequencies
associated with gear mesh or bearing defects.
Waveform Analysis
This technique is used to detect the presence and the type
of fault at an early stage of development and to monitor its
evolution.
For example, a change in the waveform over time might indicate
a developing fault, such as a crack in a gear tooth.
Time-Frequency Analysis
This method is used to analyze non-stationary signals
whose frequency content changes over time.
For instance, if a gearbox operates under varying load conditions,
the vibration signal will change over time, and this method can be
used to analyze those changes.
Order Analysis
This technique is used to analyze the vibration of rotating
machinery at different speeds.
For example, if a gearbox operates at different speeds, order
analysis can be used to compare the vibration at each speed.
Time Synchronous Average
This method is used to reduce the noise level in the
vibration signal and enhance the periodic components
related to the gear mesh.
For instance, if there is a lot of background noise in the vibration
signal, this method can be used to filter out the noise and
highlight the vibrations from the gear mesh.

46. • Lubrication in excess also has a negative impact on the state of the joints.
When there is an excess of lubricating oil, the pressure rises in the seals, which
makes them deteriorate and break. When this happens, both water and dirt can
find their way into the mechanical system.
Why Over-lubrication Can damage ?!

47. • . The basic formula for torque is τ = F * r * sin(θ), where:
• τ is the torque,
• F is the force applied,
• r is the distance from the axis of rotation (also known as the moment arm),
• θ is the angle between the force vector and the moment arm1.
• If the force is applied perpendicular to the moment arm, the angle θ is 90 degrees, and sin(θ) becomes 1. So
the formula simplifies to τ = F * r2.
• For example, if you’re calculating the torque required to lift a load using a pulley, you would multiply the
force required to lift the load (F) by the radius of the pulley ®. If the load is 20 Newtons and the radius of the
pulley is 5 cm (or 0.05 m), then the required torque for the application is 20 N * 0.05 m = 1 Nm3.
how to calculate torque for an application

48. Step Description Example
Performance Requirements
Understand the specific requirements of your
application.
If you’re building a conveyor belt system, you might need a
speed of 60 RPM, a torque of 50 Nm, a duty cycle of 8 hours
per day, and a life expectancy of 5 years.
Environment & Size
Consider the location and size requirements of
your application.
If the gearbox is going to be used in a food processing plant, it
needs to be made of food-grade materials, fit within a certain
space, and withstand high-pressure washdowns.
Efficiency
Consider the overall efficiency and/or current
draw.
If the motor driving the gearbox is rated for a certain power
level, you need to make sure the gearbox doesn’t exceed that
power level when it’s operating at its peak efficiency.
Cost Consider the cost ceiling.
If your budget for the gearbox is $500, you need to find a
gearbox that meets all your requirements without exceeding
that price.
Calculate the Required Rated Gear
Unit Torque
Calculate the basic data, select the application
factors, and calculate the required rated gear
unit torque.
If you’re lifting a 100 kg load using a pulley with a radius of
0.1 m, the required torque would be 100 kg * 9.8 m/s² * 0.1 m
= 98 Nm.

49. Gear Drive Description Selection Criteria
Concentric
Shafts on same
planes. Can be placed
in a row.
Service factor (ability to handle overloads), rating, thermal
capacity (heat dissipation), speed variation, drive ratio (speed
reduction or increase)¹
Parallel
Shafts on same plane
and parallel. For high
torque and
horsepower.
Power (motor output), velocity (speed of operation), torque
consistency (steady force), output peaks (maximum force), inertia
(resistance to change in motion), precision (accuracy of
movement)²
Right Angle
Shafts have a 90-
degree relationship.
Used where motor
needs to be close to
driven equipment.
Torque & Speed (force and rate of operation), Duty (operating
hours), Control (ease of operation), Mounting (installation),
Environment (operating conditions)³
Shaft Mount
Mounted directly
onto and supported
by the driven shaft.
Application requirements (specific needs), sizing (fit), mounting
(installation), speed (rate of operation), torque (force), accuracy
(precision of movement), repeatability (consistency of operation)⁴

54. • Scuffing is a sudden failure of the lubricant layer during operating conditions, normally occurring under
high load or high speed. It results in a sudden rise in friction and heat, causing the two surfaces to
momentarily weld together. As the mating surfaces move out of the contact zone, the weld is torn
apart, causing a gross transfer of material from one component surface to the other. In gears, scuffing
appears as rough-edged scratches, usually at the extreme ends of the contact path where sliding is at a
maximum
• Pitting, on the other hand, occurs when fatigue cracks are initiated on the tooth surface or just below
the surface. Usually pits are the result of surface cracks caused by metal-to-metal contact of asperities
or defects due to low lubricant film thickness.
• However, if you see rough-edged scratches, it might be scuffing, and if you see small pits or craters, it
might be pitting.
Scuffing Vs Pitting

59. • 1. **Pitting**: This is often the first sign of gear failure. It occurs when there is wear or pitting in the
dedendum, which is just below the pitch line where the protruding teeth of one gear fit into the second
gear¹. This can be caused by surface fatigue¹.
• 2. **Scuffing**: Also known as abnormal wear, this can occur when the lubricant film is not sufficient to
keep the gear teeth separated from each other. Without a good film of lubricant, the gears will overheat,
create noise, suffer tooth wear, and possibly fail¹.
• 3. **Cracking**: This can occur when a gear is pushed beyond its capacity, leading to fatigue¹. The most
common form of distress and failure is actual breakage¹.
• 4. **Misalignment**: This is not directly a result of lubrication breakdown, but poor lubrication can
exacerbate the effects of misalignment. Misalignment can lead to uneven wear and can accelerate the
progression to the stages of pitting, scuffing, and cracking.
The sequence of potential gear failure when lubrication breaks down
can vary depending on the specific conditions and type of gear, but
generally, the process might occur as follows:

60. • RCA (Root Cause Analysis): RCA is a technique used to identify the
underlying causes of failures or problems. It aims to address the root cause
rather than just treating the symptoms.
• FMECA (Failure Mode, Effects, and Criticality Analysis): FMECA is a
technique used to identify and evaluate potential failure modes of a
system, determine their effects, and assess their criticality to prioritize
maintenance actions.
• FMEA (Failure Mode and Effects Analysis): FMEA is a technique used to
systematically analyze potential failure modes of a system, assess their
effects, and prioritize actions to prevent or mitigate those failures.
Troubleshooting Techniques

61. Performed after failures or incidents to identify root causes- Focuses
on one specific failure event - Asks "Why did this failure happen?"-
Used to prevent recurrence of significant failures- Common tools: 5
Whys, Fishbone diagram
RCA (Root Cause Analysis)

63. Why Problem Statement Root Cause
1 The gearbox is making a grinding noise. The gears are not properly aligned.
2 Why are the gears not properly aligned? The bearings have worn out.
3 Why have the bearings worn out? The lubrication was insufficient.
4 Why was the lubrication insufficient? The lubrication schedule was not followed.
5 Why was the lubrication schedule not followed? The maintenance team was not aware of the schedule.

65.  Method  5 Whys  Fishbone
 Goal  Identify root cause behind problem  Categorize potential causes
 Process  Ask "Why?" 5 times to get to root  Gather causes under categories
 Technique  Repeating question format  Visual diagram technique
 Causes found  Single root cause  Multiple potential causes
 Categories  None, direct questioning  People, machines, materials etc
 Timeframe  Can be quick  May take more time to map
 Visual aid  None  Fishbone diagram created
 Benefit  Simple technique  Holistic view of categories

66. • Performed before or after failures- Analyzes potential failure modes
and quantifies their risk- Asks "How likely and impactful are different
failures?" - Used to rank failure modes and guide engineering efforts-
Common tools: Risk priority number (RPN)
FMEA (Failure Mode and Effects Analysis)

69. • Severity (S): Severity represents the potential impact or consequence of a failure mode
or risk. It is assigned a numerical value based on a predefined scale, often ranging from 1
to 10, where higher values indicate more severe consequences.
• Occurrence (O): Occurrence refers to the likelihood or probability of a failure mode or
risk occurring. It is also assigned a numerical value based on a predefined scale, typically
ranging from 1 to 10, where higher values indicate a higher likelihood of occurrence.
• Detectability (D): Detectability represents the ability to detect or discover a failure mode
or risk before it causes harm or undesirable consequences. Like severity and occurrence,
detectability is assigned a numerical value based on a predefined scale, with higher
values indicating a higher ability to detect the failure mode.
Risk Priority Number (RPN)

71. Failure Mode Severity (S) Occurrence (O) Detection (D) RPN
Gear teeth wear 7 4 3 84
Bearing failure 8 2 4 64
Seal leakage 6 3 5 90
Shaft misalignment 9 1 2 18

72. Failure Mode Severity (S) Occurrence (O) Detection (D) RPN
Cumulative
RPN
% of Total RPN
Gear teeth wear 7 4 3 84 84 30.4%
Bearing failure 8 2 4 64 148 53.6%
Seal leakage 6 3 5 90 238 86.2%
Shaft
misalignment
9 1 2 18 256 100%

73. Time Money
Resources Life
Why Maintenance

74. Quality
Efficiency
Safety
Operation Criteria

75. Breakdown
Anticipation
Production
Readiness
Plan
anticipation
Maintenance Goals

76. MAINTENANCE PROCEDURE
WORK ORDER
PLANNING
PERMIT TO WORK (P.T.W) AND TAGGING
SAFETY DURING MAINTENANCE WORK
TROUBLESHOOTING

77. WORK ORDER
Investigation
Wrong
Cause
to be done
how long

78. PLANNING
Analyze
Contractor Or
Manpower
Material And Parts
Basic Approach
Overhauled
Replaced
Phased Out
Operation Effect

79. Isolate The
Equipment Or
System
Put The Tag On
That.
Work Permit
Classification
Authorization
operations
supervisor
needed it to
remove the tags
When Work
Done
PERMIT TO WORK (P.T.W)

80. Beating, Grinding, Welding,
Burning, Cutting, Using An Air
Hose
Hard Hat
, Gloves
Safety Glasses
SOLVENTS ( skin irritations ,
volatile , inhaled cause illness,
death)
USE OF
RESPIRATORY
EQUIPMENT
Boots
Tagging out safety preparations

81. A mechanical
Aid Should Be
Used To Move
Anything Over
Fifty Pounds.
The Buddy
System Should
Used Whenever
Any Hazardous
Job Is Being
Performed
Moving Heavy Loads Is Often A Part Of Maintenance Work
Squatting Down,
Keeping The Back
Straight,
And Using The
Legs For Leverage.

82. Troubleshooting Manual
•machinery history record logged
Troubleshooting Reference

83. Strategies Run-to- Failure Failure-based
Preventive Time-based
Predictive Condition-based

84. Troubleshooting
Step One: Identify
distracting features
to isolate the
essential core.
Step Two: Analyze
that central issue

86. • MTBF (Mean Time Between Failures): MTBF is the average time between two
consecutive failures of a system or component. It is a measure of reliability.
• MTTF (Mean Time to Failure): MTTF is the average time until the first failure of a system
or component under normal operating conditions. It is also a measure of reliability.
• MTTR (Mean Time to Repair): MTTR is the average time required to repair a failed system
or component and restore it to normal operation. It is a measure of maintainability.
• MMTR (Mean Maintenance Time to Repair): MMTR is similar to MTTR and represents
the average time required to perform maintenance tasks and repair a failed system or
component.
Troubleshooting Metrics

88. Machinery History Record Logged
The Work Done On A Component Since Its Installation.
Initial Tests,
Maintenance Performed On A Piece During Its Operation.
Baseline Readings Difference May Indicate A Problem
Eventual Solutions,
Time Required For Repair,
Tool Used, Parts Number
Names Of Personnel Who Helped Solve Problems

89. Troubleshooting Manual
Symptoms Probable Cause
Possible Solutions

91. • FMECA (Failure Mode, Effects, and Criticality Analysis): FMECA is a
technique used to identify and evaluate potential failure modes of a
system, determine their effects, and assess their criticality to prioritize
maintenance actions.
• RCA (Root Cause Analysis): RCA is a technique used to identify the
underlying causes of failures or problems. It aims to address the root cause
rather than just treating the symptoms.
• FMEA (Failure Mode and Effects Analysis): FMEA is a technique used to
systematically analyze potential failure modes of a system, assess their
effects, and prioritize actions to prevent or mitigate those failures.
Troubleshooting Techniques

92. Performed after failures or incidents to identify root causes- Focuses
on one specific failure event - Asks "Why did this failure happen?"-
Used to prevent recurrence of significant failures- Common tools: 5
Whys, Fishbone diagram
RCA (Root Cause Analysis)

99. • Based on my search, here are some resources that might be helpful for a presentation on
Gearbox Troubleshooting, Inspection & Maintenance:
1.Top 10 tips for industrial gearbox inspection and maintenance: This article provides 10
tips to minimize downtime and ensure your gearbox experiences as long an operational
life as possible. It covers topics like gearbox ratings, good housekeeping, shaft seals,
breathers, lubrication, temperature (overheating), gear wear/contacts, backlash and
shaft end play1.
2.Gearbox Troubleshooting, Inspection & Maintenance: This course outline provides a
comprehensive overview of the fundamentals of gear contacts, geometry, and the
materials employed. It reviews the major types of gears and their diverse operational
properties. It also covers how to select a gearbox for a given application and the factors
that need to be considered. It teaches what can be learned from gear failure2.
3.Trouble shooting in gear box | PPT: This PowerPoint presentation on SlideShare might
provide some visual aids and structured information for your presentation3.
4.Gear Boxes: Operation, Inspection, Maintenance, Troubleshooting & Repair: This course
is designed to help, train and update practicing engineers in the specification,
installation, and operation of gears and gearboxes in modern systems. It covers an
introduction to gear operation, current design standards, and manufacturing methods4.
• Please note that these resources are intended to provide a starting point for your
presentation. You may need to further research and tailor the information to suit your
specific needs and audience. Good luck with your presentation!

100. Gears can be classified based on several factors such as the position of their connected axis or shaft, the shape
1.Parallel Axis Gears: In this type of gearing, the axis of both the gears tends to be parallel to each other. The t
•Spur Gears
•Helical Gears
•Double Helical or Herringbone Gears
2.Perpendicular Axis Gears: These gears have axes that are perpendicular to each other1.
3.Intersecting Gears: These gears have axes that intersect1.
4.Non-Intersecting Gears: These gears have axes that do not intersect1.
5.External Gear: This type of gear has teeth that are cut on the outer surface of the gear1.
6.Internal Gear: This type of gear has teeth that are cut on the inner surface of the gear1.
7.Rack and Pinion Gear: This type of gear arrangement involves a circular gear (the pinion) engaging with a lin
8.Straight Teeth Gear: This type of gear has teeth that are straight and parallel to the axis of the gear1.
9.Inclined Teeth Gear: This type of gear has teeth that are inclined to the axis of the gear1.
10.Curved Teeth Gear: This type of gear has teeth that are curved1.
Each type of gear arrangement has its own specific applications and is used in different types of machinery base