Hydraulic Ram Pumps

Principles and History

Hydraulic Ram Pumps (HRPs) were invented over 200 years ago (by Whitehurst and Montgolfier); they use the hydraulic potential energy of the water they pump, require minimal infrastructure and, being very simple and robust machines, need little by way of maintenance. They require no external energy source other than the potential energy of the water that they pump. HRPs also have only two moving parts. This makes them a valuable source of green energy, HRPs were very popular at the start of the 19th and end of the 20th centuries, but have since suffered from a lack of research and understanding of their potential. As a result, HRPs have been superseded by electrical equivalents.

The Cycle


Flow builds

The impulse valve is open. The exit flow begins to accelerate, water in the drive pipe gains momentum. The delivery valve is closed.


Impulse valve 'slams' shut

The flow reaches its peak and triggers the impulse valve to 'slam' shut. The column of water behind it comes to a sudden stop generating a pressure wave (The Water Hammer Effect).


Pressure wave propagates

The pressure wave now moves to equalize with the air in the air chamber. This forces the delivery valve to open and pushes water into the air chamber, leading to an increase in pressure. 


Water is pumped

The resulting increase in pressure in the air chamber, (i) closes the delivery valve and (ii) forces water into the delivery pipe. The reduced pressure in the body of the pump now allows the impulse valve to open and the cycle restarts. 


The Hydraulic Ram Pump is thus able to concentrate hydraulic potential energy and move a fraction of the water from the source to the delivery point.