The Work Theory of Film Bearing

Film bearing is a radial running bearing which uses lubricant as a media, the basic working theory is, during the rolling process, the bearing journal moves because of the rolling power, bearing center and the bearing journal has skewing, makes two zones in the gap of film bearing and journal, one is called amplification area, the gap is getting bigger and bigger according to the rotating direction, one is called constriction area, the gap is getting smaller according to the rotating direction. When the rotating journal bring the lubricant from the amplification area to the constriction area, the gap becoming smaller and smaller, forming a lubricant wedge, create pressure on the lubricant oil pressure, the pressure from every point in the film altogether is bearing capacity of film bearing, when the rolling power is bigger than the bearing capacity, the journal center and the bearing center eccentric distance enlarges, in the constriction area, the gap between bearings changing fast in the direction of journal rotating, the thickness of film get to the thinnest, the pressure of film getting bigger, carry capacity getting bigger, until balance the rolling power of the journal will not deviation, the bearing and journal completely separated by the film, become all liquid lubricant in theory.

From the film bearing theory, we can sense that the most important specification is film thickness, if the thickness is too thin, and the impurity in the lubricant is too big, which is just like metal touching directly, can lead to burning inside, meanwhile, if the thickness of the film is too thin, if steel pushing accident happens, its very easy to course direct contact which leads to burning, the smallest thickness of film is related to bearing structure material, related parts’ accuracy, and film bearing system assemble accuracy, lubricant and rolling power.