Chris, there are various types but basically you pull a spring loaded handle and a fixed amount of oil (somewhat slowly) is distributed through small lines through various manifolds and at the end of each line there is a metering nozzle to equalize the pressure through the system so all of the oil doesn't just go through the path of least resistance. These lines typically lubricate the ways, lead screws, etc. all from the one reservoir. This can be more automated on modern CNC machines and controlled pneumatically or by the control software. For nanual machines you might do this once a day or each shift in a production environment. I will try to get some pictures tomorrow of the other parts on the mill.
Bill
