Fault Phenomenon: Caterpillar D9T dozer track gearbox housing has oil stains, oil drips on the ground.

Troubleshooting Process:
– Checked oil seal: input shaft oil seal aged and hardened.
– Checked breather cap: breather clogged, high internal pressure.
– Checked oil level: overfilled.
– Checked housing: mating surface gasket damaged.

Root Cause: The track gearbox breather cap is clogged with mud; internal pressure rises during operation due to heat, blowing out the oil seal.

Required Parts: Replace oil seal and clean breather cap.