SEAL-LIP TYPE 6H3999 - Caterpillar

Entanglement of body parts in rotating gears can cause severe personal injury. Do not inspect or service the gears during operation. To avoid personal injury, keep extremities clear of the gear teeth.
Ensure that the machinery will not operate when this maintenance is performed. Attach a "DO NOT OPERATE" tag or similar warning tag to the controls before performing maintenance or repairs.Remove the cover of the gearbox and inspect the gears for wear.When a new gearbox is put into service, a common cause of concern is the appearance of initial pitting. Initial pitting is a fatigue on the surface of the gear that occurs rapidly after a new gearbox is operated. Initial pitting is the result of local high spots on the surface of the gear tooth. The local high spots are highly stressed. As the high spots wear down, the load bearing area of the tooth increases and the stress on the surface of the tooth decreases. Generally, initial pitting is not progressive. This condition is usually self-adjusting.The continuation of initial pitting is destructive. When destructive pitting occurs, the small pitted areas become larger. The pitted areas can overlap. This forms a larger pitted area. The pitted area increases to a degree that renders the undamaged area insufficient for carrying the loads. The undamaged area becomes stressed. The gear will fail if the gear is kept in service.If a case of destructive pitting occurs, replace the damaged gear. Include a check of the following items in the investigation:
Horsepower that is transmitted
Temperature of the lube oil in the gearbox
The type of lube oil in the gearbox
The amount of lube oil in the gearbox