Hydraulic ram

The first self-acting ram pump was invented by the Frenchman Joseph Michel Montgolfier (best known as a co-inventor of the hot air balloon) in 1796 for raising water in his paper mill at Voiron.

[4] The sons of Montgolfier obtained a British patent for an improved version in 1816,[5] and this was acquired, together with Whitehurst's design, in 1820 by Josiah Easton, a Somerset-born engineer who had just moved to London.

Easton's firm, inherited by his son James (1796–1871), grew during the nineteenth century to become one of the more important engineering manufacturers in England, with a large works at Erith, Kent.

Until about 1958 when the mains water arrived, the hamlet of East Dundry just south of Bristol had three working rams – their noisy "thump" every minute or so resonated through the valley night and day: these rams served farms that needed much water for their dairy herds.

In 1929, it was acquired by Green & Carter [6] of Winchester, Hampshire, who were engaged in the manufacturing and installation of Vulcan and Vacher Rams.

Priestly's Hydraulic Ram, built in 1890 in Idaho, was a "marvelous" invention, apparently independent, which lifted water 110 feet (34 m) to provide irrigation.

An example is Aid Foundation International in the Philippines, who won an Ashden Award for their work developing ram pumps that could be easily maintained for use in remote villages.

[11] The hydraulic ram principle has been used in some proposals for exploiting wave power, one of which was discussed as long ago as 1931 by Hanns Günther in his book In hundert Jahren.

[13] In 1996 English engineer Frederick Philip Selwyn patented a more compact hydraulic ram pump where the waste valve used the venturi effect and was arranged concentrically around the input pipe.

[14] Initially patented as a fluid pressure amplifier due to its different design, it is currently sold as the "Papa Pump".

This automatically inhales a small amount of air each time the delivery valve shuts and the partial vacuum develops.

[19] Another solution is to insert an inner tube of a car or bicycle tire into the pressure vessel with some air in it and the valve closed.

Suppliers of rams often provide tables giving expected volume ratios based on actual tests.

Since both efficiency and reliable cycling depend on water hammer effects, the drive pipe design is important.

The delivery pipe is much less critical since the pressure vessel prevents water hammer effects from traveling up it.

A ram newly placed into operation or which has stopped cycling should start automatically if the waste valve weight or spring pressure is adjusted correctly, but it can be restarted as follows:[17] If the waste valve is in the raised (closed) position, it must be pushed down manually into the open position and released.

Closing the valve until the ram starts cycling, then gradually opening it to fill the delivery pipe.

The cycling may stop due to poor adjustment of the waste valve, or insufficient water flow at the source.