How does a grease gun work? A grease gun is a tool designed for applying lubricating grease to machinery and components. It operates by using a piston mechanism to force grease through a nozzle and into the desired lubrication point. To use it, you load a grease cartridge into the gun, pump the handle to pressurize the grease, and then apply the nozzle to the grease fitting. As you continue to pump, the grease is pushed out and into the joint or bearing, ensuring proper lubrication and reducing friction. This process helps maintain machinery efficiency and prolongs equipment life.