Gearbox Troubleshooting, Inspection & Maintenance.pptx

Gearbox Troubleshooting, Inspection & Maintenance.pptx

1. Gearbox Troubleshooting, Inspection & Maintenance

2. 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 gear 1 . Teeth are inclined at an angle (called helix angle) with the gear axis 1 . Load on Bearings Imposes only radial load on bearings 1 . Imposes both radial and axial loads on bearings 1 . Noise and Vibration Teeth of mating gears come in sudden contact causing vibration and noise 1 2 . Teeth come in contact gradually, resulting in smoother and quieter operation 2 3 . Load Carrying Capacity Lower compared to helical gears 3 4 . Higher due to the gradual engagement of teeth 3 4 . Applications Suitable for power transmission over small distance 1 .  Used in devices like washing machines, screwdrivers, windup alarm clocks 2 . Used for high-speed transmission 4 .  Commonly used in transmissions 2

7. Spur Gear

8. Helical-Gears

9. 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

10. Worm Gears

11. Screw Gears

12. 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.

13. Term Description Gear Train A series of two or more gears used to transmit power from one shaft to another 1 . Gear Ratio The ratio of the number of teeth of the driven or output gear and the driver or input gear 1 .  It is used to calculate the speed and torque of the output shaft when input and output shafts are connected using a gear train 1 . Driver Gear The gear where we apply the torque 1 . Driven Gear The gear where we use the applied torque 1 . Idler Gears The gears used in between the driver and driven gears 1 . Output Shaft Speed Calculated as Speed of input Shaft / Gear Ratio 1 . Output Torque Calculated by multiplying the input torque with the gear ratio 1 .

14. 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. 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 = 5 1 . 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 RPM 1 . 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-m 1

15. Torque (τ) = Power / Speed (ω)

16. GR= Driven / Driver

17. 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

18. Planetary Gears

19. Parallel Gears

20. Detection of machine faults Parameters

21. 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.

22. 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.

23. 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 ?!

24. . 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

25. 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.

26. 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

27. 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

28. 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:

29. 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

30. 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)

31. 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.

32. 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

33. 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)

34. 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)

35. 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

36. 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%

37. Why Maintenance

38. Operation Criteria

39. Maintenance Goals

40. MAINTENANCE PROCEDURE

41. WORK ORDER

42. PLANNING

43. PERMIT TO WORK (P.T.W)

44. Tagging out safety preparations

45. Moving Heavy Loads Is Often A Part Of Maintenance Work

46. Troubleshooting Reference

47. 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

48. Machinery History Record Logged

49. Troubleshooting Manual

50. 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

51. 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)

52. Based on my search, here are some resources that might be helpful for a presentation on Gearbox Troubleshooting, Inspection & Maintenance: 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 play 1 . 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 failure 2 . Trouble shooting in gear box | PPT: This PowerPoint presentation on SlideShare might provide some visual aids and structured information for your presentation 3 . 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 methods 4 . 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!

53. Gears can be classified based on several factors such as the position of their connected axis or shaft, the shape of their teeth, and their application. Here are some common types of gear arrangements: Parallel Axis Gears : In this type of gearing, the axis of both the gears tends to be parallel to each other. The types of gears that come under this system are 1 : Spur Gears Helical Gears Double Helical or Herringbone Gears Perpendicular Axis Gears : These gears have axes that are perpendicular to each other 1 . Intersecting Gears : These gears have axes that intersect 1 . Non-Intersecting Gears : These gears have axes that do not intersect 1 . External Gear : This type of gear has teeth that are cut on the outer surface of the gear 1 . Internal Gear : This type of gear has teeth that are cut on the inner surface of the gear 1 . Rack and Pinion Gear : This type of gear arrangement involves a circular gear (the pinion) engaging with a linear gear (the rack), converting rotational motion into linear motion 1 . Straight Teeth Gear : This type of gear has teeth that are straight and parallel to the axis of the gear 1 . Inclined Teeth Gear : This type of gear has teeth that are inclined to the axis of the gear 1 . Curved Teeth Gear : This type of gear has teeth that are curved 1 . Each type of gear arrangement has its own specific applications and is used in different types of machinery based on the requirements of torque, speed, and direction of motion.