Down Hole Components Now that you have seen how the surface components work, it is time to understand how the down hole unit (the pump) actually works. The down hole pumping unit consists of two check valves, these valved are known as the traveling valve, and the standing valve. Both valves are opened by pressure, and closed by fluid. http://www.google.com/patents/US6290475 Standing Valve: The standing valve is on the bottom of the down hole pump, and is the valve between the pump and the formation. When the surface unit goes into an upstroke, the pump creates a decreased pressure zone between the standing valve and the traveling valve, which allows the standing valve to open, and formation fluids to flow in. When the unit goes into a down stroke, the incompressible fluid being pushed down, along with gravity forces the standing valve shut. Traveling Valve: The traveling valve does exactly what is called, it travels up and down with the pump. On the down stroke of the pump unit, the incompressible fluid that caused the standing valve to close, creates an increased pressure that allows the traveling valve to open, and fluid to flow into the pump. On the up stroke, the weight of the fluid combined with gravity forces the traveling valve to close, and this is what lifts the fluid. The combination of opening and closing valves allows the unit to successfully lift fluid to the surface. To see this phenomenon in real time click here.