Lubrication is a substance that reduces friction. If you rub your hand against your desk then put a little water on it your hand will slide across your desk easier. The water is like a lubricant. It helps to reduce friction. Another example is if you put oil on your bike, the oil will reduce friction and you can ride smoother.

This girl is putting some oil on the chain of her bike. The oil will lubricate the moving parts of her bike. Friction will be reduced. Her bike will ride smoother.

Lubrication also reduces the heat that friction makes. That is why we use oil on machines so they don't overheat and wear down. Lubrication helps our machines last longer so we don't have to replace them. They can be liquid, partly solid or solid. Lubricants help by filling in rough areas and smoothing out the surface.

Box cars use grease and oil for lubrication. Grease is used where parts slide past each other and oil is used on fast moving parts.

Here are some products used for lubrication on machines. Lubrication is a way of reducing friction by using a liquid on moving parts.

Box cars use two types of lubrication, oil and grease. Grease is longer lasting than oil. A light spray oil, like WD-40 is used to oil bearings. Grease is used for brakes.