Windmill Water Pumping

Windmill Water Pumping : How does it work

Windmill Water Pumping

Water Windmill

Water Windmill that pump water is simple and efficient design machine that has been used extensively for pumping water in the late 18th and early 19th centuries in the US and still, can be seen working in many parts of the country.

A simple diagram of windmill water pumping working is illustrated as

Windmills Water Pump illustration. (Courtesy: ironman windmills)

Windmills Water Pumping Parts and Functions

In the coming sections, we will discuss each part of the windmill water pumping system and its function. Let’s start with Windmills Blades.

Water Windmill blades

Windmill water pumping systems are mainly comprised of 18 blades.

Windmill water pumping machine blades

The blades are slightly bent to an exact curvature to efficiently capture the wind.

Windmills bent blade structure
Wind flow illustration over windmill blade

A metal rib is fitted strongly to the blade and also has a tab that slots into the hole in the sail center allowing the two sides to interlock.

Metal rib
Metal rib interlocked on the blade

The metallic bands are fit through the ribs. To assemble the sails together

Metalic band
Assembly of metalic bands

Water Windmill Sail Structure

the wheel arms that are screwed into the metallic hub hold the sails of the windmill. The sail structure is mounted on the wheel arms.

Sail Structure Wheel arm
Sail Structure metalic hub
Sail mounted on the wheel arm

Water Windmill Gearbox

The wheel hub is connected to a shaft that extends to the gearbox. The shaft drives the gear mechanism to convert rotary motion into up and down motion.

Windmill shaft connected with the Gearbox

The shaft which is connected to the wheel hub has two gears mounted on it in the gearbox. As the gears rotate along the shaft, the bigger gears that are meshed to them rotate in the opposite direction.

Gears moving in the opposite direction

The bigger gears are connected to a guide wheel by the pitman’s arms. The guide wheel is mounted on a pitman guide that allows it to slide up and down with the rotational motion of the connected gears.

A series of up and down motions illustrated as

Up motion 1
Up motion 2
Up motion 3
Down motion 1
Down motion 2
Down motion 3

Windmill Pump Rod

The guide wheel is connected to a pump rod which is extended into the ground.The pump rod goes through a cylindrical drop pipe inside the ground.

Windmill pump rod
Pump rod inside a cylinder

The pump rod is connected to a plunger that acts like a piston and has leather cups to keep the plunger in direct contact with the cylindrical wall and allows water to pass only through the valve when the plunger is making a down stroke. There is a similar check valve at the bottom of the cylinder that is fitted to a strainer below the water level in the ground.

Pump rod connected to the plunger with leather cups
Check valve and Strainer

On a downstroke, water is held in a cylinder by a check valve and the plunger descends to the bottom while the water passes through the plunger valve.

With each upstroke of the pump, the plunger forces a cylinder full of water into the drop pipe and out to the discharge tank.

on a downstroke
Before a downstroke
valve Opening

hence pumping the water out

Water pumping position 1
Water Pumping position 2
Water Storage Tank

Tailbone and vane

The gearbox is mounted on a mast pipe and is also connected to a tailbone on which the vein is bolted.

Mastpipe and Vane

The entire mill can revolve on mast pipe and the vein changes the direction of the mill according to the wind direction.

Windmill direction 1
Windmill direction 2
Windmill direction 3

Note that wheel hub or shaft is offset from the vast pipe and also the tailbone is offseton the opposite side of the mast pipe.The gearbox has a vein spring attached to the tailbone.

Shaft and Tailbone offset
Vane Spring

In high wind conditions, the wind force furls the mill counter-clockwise pivoting the mill on the mast pipe whereas the tailbone is parallel to the wind direction.

High Wind condition 1
High Wind Condition 2
Tailbone parallel to wind

The tension on the vein increases as the mill is furled and holds the mill into the wind or higher wind velocities.The increased tension on the spring causes the wheel to return into the wind when the wind velocity decreases.

Furling Action 1
Furling Action 2
Increased tension in spring

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Windmill Water Pump Important Factors

When choosing a water windmill pump, there are certain factors that need to consider while making a decision. Knowing these factors will help you to make a guided decision that meets your water pumping requirements. The amount of water that a windmill can pump depends on the following parameters

  • The number of windmill blades: It has a direct impact on windmill startup. So, If you are in a low wind speed region, then, it is better to have more blades as they widen the area to capture the wind energy
  • Wind Speed: Higher the wind speed, the higher the wind power that can be captured by windmill blades.
  • Size of Wind Pump Cylinder: The size of the wind pump cylinder dictates how much it can store the water
  • Flow rate and Head: The rate at which the windmill pumps the water is called as flow rate and the height to which it delivers the water is termed as Head. Flow rate and head are inversely proportional to each other, Higher the head would be, the higher the frictional losses in the pipe which leads to the low flow rate of pumping water.
  • Windmill wheel and Pump size: The Windmill rotor diameter and pump size must be matched according to your water pumping requirement. For instance, if you have placed a large pump and small windmill rotor blades in a deep well, at low wind speeds, it will not produce sufficient torque to raise the water at the required head. Same is the case, when a small size pump is installed in comparison to large windmill blades, in this case, even at high wind speeds, the pump at its highest capacity will only extract a fraction of the water, which does not fulfill the water requirements. So to avoid over-capacity or under-capacity, both should be properly matched.

Windmill Water Pump Types

Windmill water pump systems can be categorized into mainly two types based on the functionality and usage

Conventional Windmill Water Pump

Conventional windmill water pumps are purely mechanically driven systems. Their working principle is the same as described in the above section. One of the limitations of a wind-driven pump is that it must be placed above or close to the water reservoir.

As the wind is an intermittent resource, so it can not work all the time. To make this system reliable, it is a must to have a water storage site at some height, so that water flow is gravity driven and does not need extra power.

A picture of an old classical Windmill water pump system
Windmill pumping water out of the canal

Wind Electric Water Pump

So instead of using a mechanical pump, wind-driven electric pumps system have high reliability and low maintenance. In this case, the wind turbine is used to harness the wind energy and produce electricity via an electric generator and thus this electricity is directly provided to an electric pump. The Wind driven electric water pump has certain advantages over conventional mechanical water pumps such as

  • Wind electric pump can be placed at a convenient place and does not need to be close to the water reservoir.
  • A wind turbine system can be installed at a far good wind resource place
  • To maximize the availability, electricity can be stored in a battery power bank and this power can be used in times of no wind.


The working mechanism of the windmill water pump has been repurposed from this video

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