Pillow block bearings are a typical style of bearing. These bearings are composed of a self-aligning ball bearing (the commonly used type) and plummer block. They can be attached to a shaft by fastening a ball retaining screw. Since they are easy to attach, they are known for their extensive use in equipment such as transmission systems and general machinery. Pillow block bearings include cast iron and steel plate types. An extensive array of cast iron models is available. Examples include thick-walled models, models mounted near to/far from the spindle center, and reduced-weight models. Cast iron models and steel plate models differ in strength, hardness, durability and other properties. When using pillow block bearings, factors such as material and shape should be considered to choose the right model for the equipment.