Root Cause Analysis 1 min read

Analysis of the occurrence of oil leakage in the gearbox: the choice of seals, ventilation and assembly errors

Technical analysis: F3-ECT5-10C-0B-MUH7-20TB

Аналіз виникнення витоку масла в коробці передач: вибір ущільнень, вентиляція та помилки зборки - UNITEC-D Industrial MRO
Витік масла в коробці передач може виникнути через неправильний вибір ущільнень, вентиляції та помилки зборки. Виконання діагностики, заміна компонентів та встановлення стратегії запобігання може усун

Introduction

Transmission oil leakage is a threat to safety and production efficiency. This phenomenon often leads to process stoppages, increased repair costs, and affects the longevity of equipment. This article examines a specific case of VICKERS F3-ECT5-10C-0B-MUH7-20TB gearbox oil leakage and analyzes its cause in terms of seal selection, ventilation and assembly errors.

Overview of the component

The VICKERS F3-ECT5-10C-0B-MUH7-20TB gearbox is used in industrial systems to transmit motion. It operates at temperatures of 40–120 °C, pressures up to 30 bar, and rotation speeds from 1000 to 3000 rpm. The main function is to ensure reliable and efficient energy transfer from the engine to the working body.

Signs of an oil leak

The technician discovered an oil leak from the seal on the output shaft. The leak occurred constantly, with an increase during peak loads. The oil temperature at the time of the leak was 115 °C and the box pressure was 28 bar. Vibration measurements showed a value of 5.2 mm/s, which exceeded the permissible limit of 4.5 mm/s.

Investigation of the causes of the leak

5 Whys, Ishikawa and defect tree methods were used to determine the causes of leakage. It turned out that the leak was caused by several factors that interacted with each other.

Causes of oil leakage

  • 1. Incorrect choice of seal (probability: 40%) - use of a seal with inappropriate characteristics, which does not ensure tightness at high temperatures.
  • 2. Inadequate ventilation (probability: 30%) - Lack of proper ventilation leads to increased internal pressure, which increases leakage.
  • 3. Assembly errors (probability: 20%) - improper seal placement or lack of proper clearance size.
  • 4. Insufficient life (probability: 10%) - leakage may occur due to seal wear after 10,000 hours of operation.

Elimination measures

1. Seal replacement - use of seals that comply with EN 13157 and ISO 13373 standards, with high heat resistance (up to 130 °C) and a high level of operational durability.

2. Installation of a vent valve - Using a valve with a high level of tightness that meets the ISO 8339 standard ensures a leak-free vent.

3. Assembly Check - Check the gap size using a 0.01mm micrometer and install the seal according to the manufacturer's specifications.

4. Lifetime maintenance - set routine maintenance every 5000 hours of operation to avoid seal wear.

Quick diagnostic check

  1. Measure the oil temperature in the gearbox. If above 120 °C, check ventilation.
  2. Inspect the outer surface of the gearbox for oil leaks.
  3. Measure the pressure in the gearbox. If it exceeds 30 bar, check the vent valve.
  4. Take vibration measurements. If it exceeds 4.5 mm/s, diagnose the seals.
  5. Check the clearance at the seal assembly using a micrometer.
  6. Assess the condition of the seal. If there are signs of wear, replace.
  7. Perform a leak test after installing new seals.
  8. Record the results and establish a maintenance schedule for the next 5,000 hours.

Prevention strategy

To prevent oil leakage, the following actions must be performed:

  • Set regular maintenance every 5000 hours of operation.
  • Use seals that comply with EN 13157 and ISO 13373. standards
  • Install ventilation valves corresponding to ISO 8339.
  • Perform vibration and oil temperature measurements on a regular basis.
  • Perform seal assembly checks using a micrometer.

Conclusion

Transmission oil leaks can occur for several reasons, including improper seal selection, ventilation, and assembly errors. To eliminate this phenomenon, it is necessary to perform diagnostics, replace components and establish a prevention strategy. To replace seals and vent valves according to standards, visit the UNITEC-D E-Catalog.

Special tools for diagnostics

The following tools are used to diagnose an oil leak:

  • Digital thermometer - oil temperature measurement with an accuracy of 0.1 °C.
  • Manometer — pressure measurement in the gearbox with an accuracy of 0.5 bar.
  • Vibration analyzer - vibration measurement with an accuracy of up to 0.01 mm/s.
  • Micrometer - measurement of the gap at the place of assembly of the seal with an accuracy of 0.01 mm.

Recommendations for technicians

Technicians should pay attention to the following "red flags" that may indicate danger:

  • Increase in oil temperature.
  • Increased pressure in the gearbox.
  • Increased vibration.
  • The presence of an oil leak.

List of references

  • ISO 13373:2016 - Requirements for seals for equipment.
  • EN 13157:2017 - Requirements for maintenance of gearboxes.
  • ISO 8339:2019 — Requirements for ventilation valves.
  • Manual VICKERS F3-ECT5-10C-0B-MUH7-20TB — Technical conditions of the manufacturer.
  • Handbook of Failure Analysis — Technical reference.

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