Since a reducer is a transmission device, many faults often occur during its operation due to external working conditions (e.g., bearing heavy loads) and internal factors. Common faults during reducer use include: oil leakage, overheating of bearing areas, excessive noise, excessively high oil sump temperature (above 70°C), abnormal noises, axial shaft movement of the driving shaft, bearing cracking, gear damage, etc. This article analyzes the causes of these faults and proposes preventive measures.

(1) Oil leakage

1. The most common leakage occurs at the seals of the driving and driven shafts, especially at the driving shaft seal.

   Solutions: Replace the seal, clean and reassemble properly, reapply sealant; when applying sealant, ensure correct positioning, even application without breaks; add an appropriate amount of oil.

2. Oil leakage at the contact surfaces of the reducer housing (various end covers).

   Solutions: Tighten or replace bolts, remove surface contaminants, remove old sealant, reapply sealant; ensure correct positioning, even application without breaks; add an appropriate amount of oil.

3. Oil leakage at the oil level window or drain plug.

   Solutions: Check whether the oil plug is loose or damaged, then tighten or replace it.

4. Oil leakage at the bottom of the reducer housing.

   Solutions: Inspect the extent of housing damage and carry out appropriate repair measures.

(2) High temperature

Excessively small gear backlash in the reducer, insufficient lubrication, bearing misalignment, non-concentric related components, excessive lubricating oil (poor heat dissipation efficiency under high speed and heavy load), excessive preload on support bearings during assembly, prolonged overload operation, and blockage of the breather vent can all lead to high temperatures.

Solutions: Adjust all clearances (gear backlash adjustment applies only to gears with perpendicular axes), adjust the oil fill amount. Our center has also effectively controlled high temperatures in many reducers by adding cooling fans, providing a good reference for future high‑temperature control. Additionally, online monitoring should be implemented for reducers operating over long periods.

(3) Overheating or noise at reducer bearing areas

Insufficient lubricating oil. If the oil level is too low or cannot reach the required height due to leakage, it may cause high temperature or abnormal noise at the bearing areas.
Friction between bearing cover or seal parts. Improper bearing installation, misaligned bearing covers, or long‑term wear between the bearing cover/seal and adjacent parts may cause high temperature or noise.
Bearing damage or wear. This mainly refers to damaged bearing cages, wear or deformation of inner/outer rings, or wear/loss of rolling elements. Any of these can prevent the reducer from working properly.
Excessive or insufficient bearing clearance. Long‑term use may increase the clearance between rolling elements and rings, between the inner ring and shaft, or between the bearing and end cover, all of which can produce the above symptoms.

Prevention and troubleshooting methods:

1. Check the oil level and add lubricating oil.

2. Tighten bearing and connecting bolts, inspect seal installation.

3. Inspect bearings and replace them immediately if damaged.

4. If the clearance is inappropriate, adjust it; replace the bearing if adjustment is not possible.

(4) Excessive vibration of the reducer

Loose foundation bolts. Long‑term operation may cause foundation bolts to loosen or become damaged, inevitably leading to excessive vibration and abnormal operation.
Gear damage. This includes severe pitting, excessive gear backlash, severe tooth wear, and broken teeth. Any of these conditions can cause excessive vibration and prevent normal operation.
Shaft deformation and imbalance. Shaft deformation may occur when the shaft's strength or hardness is below requirements or due to aging from long‑term use. Deformation causes excessive reducer vibration.

Prevention and troubleshooting methods:

1. Tighten the foundation bolts.

2. Inspect the damaged parts and causes in the coupling, and repair it promptly.

3. Tighten loose motor bolts.

4. Replace bearings.

5. Replace gears.

6. Replace shafts.

(5) Abnormal noise in the reducer

1. Reducer overload operation. —>  Operate according to specified requirements.

2. Imbalanced load from the working machine. —> Adjust the balance condition.

3. Deteriorated lubricating oil. —> Drain deteriorated lubricating oil, clean thoroughly, and replace with qualified oil.

4. Worn gear teeth or poor manufacturing quality. —> Send the reducer to a repair shop for overhaul and replacement of parts.

5. Excessive or insufficient bearing clearance. —> Adjust bearing clearance.

6. Adherent debris on tooth surfaces. —> Inspect and clean.

7. Foreign matter inside the housing. —> Drain oil and clean.