Sleeve bearings use sliding motion instead of rolling elements to carry heavy loads. Plain bearing bushings, which resemble a simple metal sleeve, absorb and distribute friction from rotating shafts. They are less durable than ball and roller bearings, but they are easy to install and operate. Hydrodynamic bearings replace bearing rolling elements with a continuous flow of water or oil. They can carry heavy loads up to several tons and have a long lifespan due to constant lubrication and no metal-to-metal contact. Clip bearings mount in sheet metal plate bore holes to support shafts. They have an angled slit so the bearing can safely expand in hot, humid environments. Clip bearings are easy to install and are self-aligning to fit into imprecisely formed sheet metal.