Manual Lubrication

This is the most primitive method, using an oiler to supply oil when the bearing's lubricating oil is insufficient. However, this method is difficult to maintain a constant oil level, and the risk of forgetting to add oil is relatively high. It is usually only used in light-load, low-speed, or intermittent operation applications. For best results, a dust cover or ball valve should be installed on the oil filling hole, and a filter device such as felt, cotton, or wool should be used.
Drip Lubrication
This is typically used for light-load and medium-load bearings with circumferential speeds less than 4-5 m/s. A roughly fixed amount of lubricating oil is supplied from a container through a hole, needle, or valve. The most classic method is a drip oil cup. The amount of oil dripped varies significantly depending on the viscosity of the lubricating oil, the bearing clearance, and the location of the oil supply hole.
Oil Ring Lubrication
This method uses a rotating ring attached to the shaft to carry lubricating oil from the oil sump to the bearing (only applicable to horizontal shafts). It is suitable for medium-speed and high-speed bearings with a shaft diameter greater than 50 mm. The oil ring should ideally be seamless. If the bearing width-to-diameter ratio is less than 2, only one oil ring is needed; otherwise, two oil rings are required.
Oil Bath Lubrication
This lubrication method involves immersing a portion of the bearing in lubricating oil. It is commonly used for thrust bearings on vertical shafts but not suitable for radial bearings on horizontal shafts.
Splash Lubrication
This method supplies lubricating oil to the bearing by splashing it up from the impact of rotating parts in an oil tank. It is suitable for high-speed bearings.
Spray Lubrication
This method atomizes the lubricating oil and sprays it onto the friction surfaces. It is suitable for high-speed bearings.
Circulating Oil Lubrication
This method uses an oil pump to deliver filtered oil to the bearing components. The lubricating oil that has passed through the bearing is then filtered and cooled before use. Because circulating oil can carry away some heat, thus cooling the bearing, this method is suitable for high-speed bearing components.