Troubleshooting / Gearbox

Gearbox Troubleshooting

The most common gearbox problems on the plant floor, with the likely causes and the fix for each. Part of the OEE Lab directory of 301+ documented problems.

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Problems on this page:

Overheating

Hits OEE: Availability

Symptoms: High case temperature, thinning oil, discolouration.

Overfilled or low oil
Set oil to the correct level; both extremes cause heat.
Wrong lubricant
Use the specified grade/viscosity.
Overload
Confirm load within rating; check service factor.
Blocked cooling/breather
Clean cooling surfaces; clear the breather.

Prevention: Oil level/analysis, correct lubricant, load and breather checks.

Noise or whine

Hits OEE: Quality

Symptoms: Whine, growl or knocking that changes with speed/load.

Worn/pitted gears
Inspect gear teeth; replace worn gearsets.
Bearing wear
Identify and replace failing bearings.
Backlash/misalignment
Check and reset backlash; align input/output.
Low/contaminated oil
Top up or change oil; investigate contamination source.

Prevention: Oil analysis, vibration checks, alignment, contamination control.

Oil leak

Hits OEE: Availability

Symptoms: Oil around seals/joints, dropping level, housekeeping/slip hazard.

Worn input/output seals
Replace shaft seals; inspect shaft surface.
Blocked breather (pressure build-up)
Clean/replace the breather to relieve pressure.
Overfilled oil
Drain to correct level.

Prevention: Seal inspection, keep breather clear, correct fill level.

Oil leakage

Hits OEE: Availability

Symptoms: Oil around seals or joints, falling oil level, contamination risk.

Worn shaft seals
Replace the input/output seals; check shaft condition.
Blocked breather (pressure build-up)
Clean or replace the breather to relieve pressure.
Overfilling or wrong oil
Set the correct level and grade; check the gasket/joints.

Prevention: Seal and breather maintenance, correct oil level and grade.

Gearbox troubleshooting FAQ

Gearbox: what causes overheating, and how do I fix it?

Symptoms: High case temperature, thinning oil, discolouration. Likely causes: Overfilled or low oil; Wrong lubricant; Overload; Blocked cooling/breather. Fixes: Set oil to the correct level; both extremes cause heat. Use the specified grade/viscosity. Confirm load within rating; check service factor. Clean cooling surfaces; clear the breather. Prevention: Oil level/analysis, correct lubricant, load and breather checks.

Gearbox: what causes noise or whine, and how do I fix it?

Symptoms: Whine, growl or knocking that changes with speed/load. Likely causes: Worn/pitted gears; Bearing wear; Backlash/misalignment; Low/contaminated oil. Fixes: Inspect gear teeth; replace worn gearsets. Identify and replace failing bearings. Check and reset backlash; align input/output. Top up or change oil; investigate contamination source. Prevention: Oil analysis, vibration checks, alignment, contamination control.

Gearbox: what causes oil leak, and how do I fix it?

Symptoms: Oil around seals/joints, dropping level, housekeeping/slip hazard. Likely causes: Worn input/output seals; Blocked breather (pressure build-up); Overfilled oil. Fixes: Replace shaft seals; inspect shaft surface. Clean/replace the breather to relieve pressure. Drain to correct level. Prevention: Seal inspection, keep breather clear, correct fill level.

Gearbox: what causes oil leakage, and how do I fix it?

Symptoms: Oil around seals or joints, falling oil level, contamination risk. Likely causes: Worn shaft seals; Blocked breather (pressure build-up); Overfilling or wrong oil. Fixes: Replace the input/output seals; check shaft condition. Clean or replace the breather to relieve pressure. Set the correct level and grade; check the gasket/joints. Prevention: Seal and breather maintenance, correct oil level and grade.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Stop the same fault coming back

Recurring gearbox stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: EU-built, so your production data stays in EU jurisdiction, with computer-vision true-cause of micro-stops, a closed loop from PLC-read OEE to an auto-routed work order, and ISO 27001 / 20000-1 / 9001 (supports audit-readiness).

See how Fabrico finds root cause
OEE Lab is built and operated by Fabrico. The directory stays free.

Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary

Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover