Hydraulic_ram - Wikiparency

# Hydraulic ram A **hydraulic ram**, or ram pump, is a water pump that runs on the [[Energy|energy]] of the [[Water|water]] flowing through it, with no fuel or electricity. Water runs downhill through a drive pipe and out of a valve that slams shut when the flow gets fast enough. The sudden stop creates a pressure surge, called water hammer, that forces a small part of the water up to a height much greater than the fall that drives it. The rest of the water spills out and the cycle repeats, typically 30 to 100 times a minute.[^clemson][^practical] A ram can lift water ten feet or more for every foot of fall, but it delivers only a fraction of the water that passes through it.[^clemson] On the Thury spine, the hydraulic ram is [[Hydropower|hydropower]] turned into pumping. Like a [[Water_wheel|water wheel]] it takes its power from falling water, but it has no wheel and only two moving valves. It uses the momentum of a moving column of water, the same inertia that makes water hammer dangerous in pipes, to do useful work. ## History John Whitehurst built a "machine for raising water" in 1772 at Oulton, Cheshire, for Philip Egerton's estate. It supplied a brewhouse and other buildings through a main pipe an inch and a half in diameter and nearly two hundred yards long. Whitehurst described it to Benjamin Franklin and in the *Philosophical Transactions* of 1775.[^whitehurst-franklin][^whitehurst1775] His valves had to be worked by hand. In 1796 Joseph Michel Montgolfier made a ram that could run by itself, and Matthew Boulton took out a British patent on his behalf the next year.[^lienhard][^clemson] Self-acting rams stayed in use on farms and estates until electric motors finally began replacing them.[^lienhard][^clemson] ## Construction and principle of operation A ram has a drive pipe coming down from a source, a waste valve, a delivery (check) valve, an air chamber and a delivery pipe going up to the tank. It needs a steady supply of water and some [[Hydraulic_head|head]], the height of the source above the ram, which [[Gravity|gravity]] turns into flow.[^clemson] ### Sequence of operation 1. Water flows down the drive pipe and out through the open waste valve, speeding up as it goes. 2. When the flow is fast enough, the drag of the water "pushes the valve's flapper up and slams it shut."[^clemson] 3. Closing a valve very rapidly creates a pressure surge, or shock wave. The surge forces water through the delivery valve into the pressure chamber.[^clemson] 4. The compressed air in the chamber acts like the pressure tank on a well, cushioning the shock and pushing a steady stream up the delivery pipe.[^clemson] 5. The pressure in the drive pipe falls, the delivery valve closes, the waste valve drops open and the cycle begins again. The flow past the waste valve is a matter of [[Drag_(physics)|drag]], and the speed the water reaches in the drive pipe follows from the head, as in [[Bernoulli's_principle|Bernoulli's principle]]. The pressure surge itself is a wave in the water, the liquid counterpart of the pressure waves studied in compressible flow. ### Efficiency A ram trades volume for height. Clemson University's extension guide says a ram pumps about one gallon for every eight gallons that pass through it.[^clemson] Practical Action's technical brief says that more than 50% of the energy of the driving flow can be transferred to the delivery flow.[^practical] The delivery rate can be estimated as the drive flow times the fall times an efficiency factor, divided by the lift.[^appropedia] An emergency water guide gives a wider range: water can be pumped 20 to 40 times higher than the available fall, but less than 10% of the water reaches the outlet.[^ewash] ### Drive and delivery pipe design The drive pipe carries the moving column of water whose sudden stop powers the pump; Whitehurst's 1772 machine used one nearly two hundred yards long.[^whitehurst-franklin] Practical Action's brief tabulates the delivery of commercial rams for ratios of lift to fall from 5:1 to 20:1: the higher the lift, the smaller the flow delivered.[^practical] ### Common operational problems The air chamber takes the full force of every surge. Whitehurst's first chamber, made of sheet lead, burst within a few months.[^whitehurst-franklin] Without its air cushion, a ram delivers the shock straight into the delivery pipe instead of a steady outlet pressure.[^clemson] ## See also - [[Hydropower]] - [[Water_wheel]] - [[Hydraulic_head]] - [[Hydraulic_engineering]] - [[Fluid_dynamics]] ## References [^clemson]: Smith, W. B. (2019). "Homemade Hydraulic Ram Pump for Livestock Water." Clemson University Land-Grant Press, LGP 1017. https://lgpress.clemson.edu/publication/homemade-hydraulic-ram-pump-for-livestock-water/ [^practical]: Practical Action. "Hydraulic Ram Pumps." Technical brief. https://sswm.info/sites/default/files/reference_attachments/PRACTICAL%20ACTION%204000%20Hydraulic%20Ram%20Pumps.pdf [^appropedia]: "Practical Action/Hydraulic ram pumps." Appropedia. https://www.appropedia.org/Practical_Action/Hydraulic_ram_pumps [^ewash]: German Toilet Organization; FHNW. "Hydraulic Ram (Impulse) Pump." Emergency WASH eCompendium. https://www.emergency-wash.org/water/en/technologies/technology/hydraulic-ram-impulse-pump [^whitehurst-franklin]: "John Whitehurst to Benjamin Franklin, [before 16 March 1775]." *The Papers of Benjamin Franklin*, Founders Online, National Archives. https://founders.archives.gov/documents/Franklin/01-21-02-0292 [^whitehurst1775]: Whitehurst, John (1775). "Account of a machine for raising water, executed at Oulton, in Cheshire, in 1772." *Philosophical Transactions of the Royal Society* 65: 277–279. https://doi.org/10.1098/rstl.1775.0026 [^lienhard]: Lienhard, John H. "Hydraulic Ram." *The Engines of Our Ingenuity*, episode 2116. University of Houston. https://engines.egr.uh.edu/episode/2116 ## Further reading - Bar-Meir, Genick (2026). *Fundamentals of Compressible Flow Mechanics* — for the pressure waves behind water hammer; on the [[PORTAL_WT!Thury_Hydrodynamics_Compendium|Compendium]] Fluid core shelf. ## External links - [Hydraulic ram pumps](https://www.appropedia.org/Practical_Action/Hydraulic_ram_pumps), Appropedia  **Part of the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]]** — main article for section 31, *Water that pumps itself*. Related sections: [[Hydropower]] · [[Compressible_flow]].   **Microsim — three.js (Wikitube framework):** *Hydraulic ram* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/thury/Hydraulic_ram.html" data-title="Hydraulic ram"></div> *Built from `MICROSIM_GUIDE/specs/sims/Hydraulic_ram.json`; part of the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]] set.*  ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Hydraulic_ram) : [Wikitube](https://en.wikitube.io/wiki/Hydraulic_ram) · pinned revision [1352636762](https://en.wikipedia.org/w/index.php?oldid=1352636762) · 2026-09-10 ## Previous hub tags Hubs: `Life_Physics`, `Systems`. Portals: [[PORTAL_Thury_Hydrodynamics_Apex_Spine]], [[PORTAL_Energy]]. --- *Thury main articles, wave 2 · 2026-09-10 · drafted · Compendium section 31 · sim pending THY-061.*