Certified Maintenance and Reliability Technician (CMRT) Practice Test

A plain bearing refers to a simple type of bearing that operates on the principle of sliding motion, where two surfaces come into contact with minimal friction. The statement accurately describes a plain bearing being parallel to the shaft; in fact, this is a fundamental feature of its design. In many applications, plain bearings are comprised of a sleeve that fits over the shaft, which is where the lubrication comes into play. Proper lubrication inside the sleeve reduces wear and tear through the formation of a film between the bearing surface and the shaft, enhancing longevity and performance. The lubrication method is critical as it prevents direct metal-to-metal contact, thereby decreasing friction and heat generation. This is why the first choice is correct—plain bearings are indeed designed to be installed parallel to the shaft and often utilize sleeves for lubrication.