Hello everybody, I am doing ICS Btec Mech Eng course at the moment and I've stuck in a question about frictions. So I have to explain journal friction, bearing pressure, sliding friction and rolling friction in relation to friction. I've found following: Sliding friction appears between two objects when they start moving against to each other. We can reduce friction between these object if apply some lubrication (usually we use oil) The force resisting the motion when a body rolls on a surface is called the rolling resistance or rolling friction. But what is a bearing preassure and journal friction? Does anybody can help with definitions please? Thank you in advance.