What is commonly used to lubricate gears in machinery?

Gears in machinery require specific lubrication to ensure smooth operation and reduce wear over time. Gear oil or grease is designed to adhere to the gear surfaces, providing a protective film that can withstand high pressures and temperatures. This type of lubrication is essential because it minimizes metal-to-metal contact, preventing damage and overheating.

Gear oil typically has a higher viscosity to maintain its film strength under load, while grease offers the advantage of remaining in place longer, making it ideal for applications where maintaining a lubrication reservoir is crucial. Both options provide appropriate properties such as anti-wear additives, which help protect the gear surfaces during operation.

The other substances listed do not provide suitable lubrication for gears. Motor oil, while useful in engines, lacks the necessary properties for effective gear lubrication. Water can lead to rust and corrosion, and kerosene, being a thin and volatile substance, does not have the required viscosity or lubricating properties to protect gears effectively.