Ball bearings transmit a load from a rotating surface to a fixed surface via a series of rotating balls. They are generally inexpensive, do not require any separate lubrication system, and can be designed to be selfaligning. However, they have limited ability to handle thrust, high loads, or high speeds.
Roller bearings transmit load from a rotating surface to a fixed surface via a series of rotating cylinders. They have high thrust capability, and do not require any separate lubrication system. However, like ball bearings they have a limited load/speed capability.
Hydrodynamic sleeve bearings (journal bearings) transmit the load through a thin oil film between a rotating shaft and a fixed bearing surface. They are particularly well suited for high load/speed applications. API 610 requires them on all barrel pumps when the product of the bearing diameter in millimeters times the pump speed in rpm exceeds 500,000 or when the product of pump rated horsepower and pump rpm exceeds 5.4 million. Sleeve bearings have long lives because there is no
rubbing between surfaces and they provide some degree of vibration dampening. However, they require a continuous, contaminant-free oil system and have no thrust capability.
Hydrodynamic thrust, or Kingsbury bearings, are the most expensive. The load is transmitted through a thin oil film between a rotating shaft and a fixed bearing surface that consists of multiple pads that tilt. These bearings have all the advantages of sleeve bearings, but in addition they have high thrust loading capability.