Gravity pumps include the and – and there also important or foggara systems which simply use downhill flow to take water from far-underground aquifers in high areas to consumers at lower elevations. The is also sometimes referred to as a gravity Pump Australia. With only one cylinder the fluid flow varies between maximum flow when the plunger moves through the middle positions, and zero flow when the plunger is at the end positions. A lot of energy is wasted when the fluid is accelerated in the piping system. Vibration and “water hammer” may be a serious problem. In general the problems are compensated for by using two or more cylinders not working in phase with each other..