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Waterwheel Design and the Different Types of Waterwheel Article April 29, 2024 at 4:57 am 2024-04-29T04:57:03-04:00
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Waterwheel Design

Waterwheel Design for Hydro Energy

hydro energy iconHydro energy is a technology that converts the kinetic energy of moving water into mechanical or electrical energy, and one of the earliest devices used to convert the energy of moving water into usable work was the Waterwheel Design.

Water wheel design has evolved over time with some water wheels oriented vertically, some horizontally and some with elaborate pulleys and gears attached, but they are all designed to do the same function and that is too, “convert the linear motion of falling water into a rotary motion which can be used to drive any piece of machinery connected to it via a rotating shaft”.

waterwheel design
Typical Waterwheel Design

Early Waterwheel Design were quite primitive and simple machines consisting of a vertical wooden wheel with wooden blades or buckets fixed equally around their circumference all supported on a horizontal shaft with the force of the water flowing underneath it pushing the wheel in a tangential direction against the blades.

These vertical waterwheels were vastly superior to the earlier horizontal waterwheel design by the ancient Greeks and Egyptians, because they could operate more efficiently translating the hydrokinetic energy of the moving water into mechanical power. Pulleys and gearing was then attached to the waterwheel which allowed a change in direction of a rotating shaft from horizontal to vertical in order to operate millstones, saw wood, crush ore, stamping and cutting etc.

Types of Water Wheel Design

Most Waterwheels also known as Watermills or simply Water Wheels, are vertically mounted wheels rotating about a horizontal axle, and these types of waterwheels are classified by the way in which the water is applied to the wheel, relative to the wheel’s axle. As you may expect, waterwheels are relatively large machines which rotate at low angular speeds, and have a low efficiency, due to losses by friction and the incomplete filling of the buckets, etc.

The action of the water pushing against the wheels buckets or paddles develops torque on the axle but by directing the water at these paddles and buckets from different positions on the wheel the speed of rotation and its efficiency can be improved. The two most common types of waterwheel design is the “undershot waterwheel” and the “overshot waterwheel”.

The Undershot Waterwheel

Undershot Water Wheel Design

undershot waterwheel design

The Undershot Water Wheel Design, also known as a “stream wheel” was the most commonly used type of waterwheel designed by the ancient Greeks and Romans as it is the simplest, cheapest and easiest type of wheel to construct.

In this type of waterwheel design, the wheel is simply placed directly into a fast flowing river and supported from above. The motion of the water below creates a pushing action against the submerged paddles on the lower part of the wheel allowing it to rotate in one direction only relative to the direction of the flow of the water.

This type of waterwheel design is generally used in flat areas with no natural slope of the land or where the flow of water is sufficiently fast moving. Compared with the other waterwheel designs, this type of design is very inefficient, with as little as 20% of the waters potential energy being used to actually rotate the wheel. Also the waters energy is used only once to rotate the wheel, after which it flows away with the rest of the water.

Another disadvantage of the undershot water wheel is that it requires large quantities of water moving at speed. Therefore, undershot waterwheels are usually situated on the banks of rivers as smaller streams or brooks do not have enough potential energy in the moving water.

One way of improving the efficiency slightly of an undershot waterwheel is to divert a percentage off the water in the river along a narrow channel or duct so that 100% of the diverted water is used to rotate the wheel. In order to achieve this the undershot wheel has to be narrow and fit very accurately within the channel to prevent the water from escaping around the sides or by increasing either the number or size of the paddles.

The Overshot Waterwheel

Overshot Waterwheel Design

overshot waterwheel design

The Overshot Water Wheel Design is the most common type of waterwheel design. The overshot waterwheel is more complicated in its construction and design than the previous undershot waterwheel as it uses buckets or small compartments to both catch and hold the water.

These buckets fill with water flowing onto the wheel through a penstock design above. The gravitational weight of the falling water in the full buckets causes the wheel to rotate around its central axis as the empty buckets on the other side of the wheel become lighter.

This type of water wheel uses gravity to improve output as well as the water itself, thus overshot waterwheels are much more efficient than undershot designs as almost all of the water and its weight is being used to produce output power. However as before, the waters energy is used only once to rotate the wheel, after which it flows away with the rest of the water.

Overshot waterwheels are suspended above a river or stream and are generally built on the sides of hills providing a water supply from above with a low head (the vertical distance between the water at the top and the river or stream below) of between 5-to-20 meters. A small dam or weir can be constructed and used to both channel and increase the speed of the water to the top of the wheel giving it more energy but it is the volume of water rather than its speed which helps rotate the wheel.

Generally, overshot waterwheels are built as large as possible to give the greatest possible head distance for the gravitational weight of the water to rotate the wheel. However, large diameter waterwheels are more complicated and expensive to construct due to the weight of the wheel and water.

When the individual buckets are filled with water, the gravitational weight of the water causes the wheel to rotate in the direction of the flow of water. As the angle of rotation gets nearer to the bottom of the wheel, the water inside the bucket empties out into the river or stream below, but the weight of the buckets rotating behind it causes the wheel to continue with its rotational speed.

Once the bucket is empty of water it continues around the rotating wheel until it gets back up to the top again ready to be filled with more water and the cycle repeats. One of the disadvantages of an overshot waterwheel design is that the water is only used once as it flows over the wheel.

The Pitchback Waterwheel Design

Pitchback Water Wheel Design

pitchback waterwheel design

The Pitchback Water Wheel Design is a variation on the previous overshot waterwheel as it also uses the gravitational weight of the water to help rotate the wheel, but it also uses the flow of the waste water below it to give an extra push. This type of waterwheel design uses a low head infeed system which provides the water near to the top of the wheel from a pentrough above.

Unlike the overshot waterwheel which channelled the water directly over the wheel causing it to rotate in the direction of the flow of the water, the pitchback waterwheel feeds the water vertically downwards through a funnel and into the bucket below causing the wheel to rotate in the opposite direction to the flow of the water above.

Just like the previous overshot waterwheel, the gravitational weight of the water in the buckets causes the wheel to rotate but in an anti-clockwise direction. As the angle of rotation nears the bottom of the wheel, the water trapped inside the buckets empties out below. As the empty bucket is attached to the wheel, it continues rotating with the wheel as before until it gets back up to the top again ready to be filled with more water and the cycle repeats.

The difference this time is that the waste water emptied out of the rotating bucket flows away in the direction of the rotating wheel (as it has nowhere else to go), similar to the undershot waterwheel principal. Thus the main advantage of the pitchback waterwheel is that it uses the energy of the water twice, once from above and once from below to rotate the wheel around its central axis.

The result is that the efficiency of the waterwheel design is greatly increased to over 80% of the waters energy as it is driven by both the gravitational weight of the incoming water and by the force or pressure of water directed into the buckets from above, as well as the flow of the waste water below pushing against the buckets. The disadvantage though of an pitchback waterwheel is that it needs a slightly more complex water supply arrangement directly above the wheel with chutes and pentroughs.

The Breastshot Waterwheel Design

Breastshot Water Wheel Design

breastshot waterwheel design

The Breastshot Water Wheel Design is another vertically-mounted waterwheel design where the water enters the buckets about half way up at axle height, or just above it, and then flows out at the bottom in the direction of the wheels rotation. Generally, the breastshot waterwheel is used in situations were the head of water is insufficient to power an overshot or pitchback waterwheel design from above.

The disadvantage here is that the gravitational weight of the water is only used for about one quarter of the rotation unlike previously which was for half the rotation. To overcome this low head height, the waterwheels buckets are made wider to extract the required amount of potential energy from the water.

Breastshot waterwheels use about the same gravitational weight of the water to rotate the wheel but as the head height of the water is around half that of a typical overshot waterwheel, the buckets are a lot wider than previous waterwheel designs to increase the volume of the water caught in the buckets.

The disadvantage of this type of design is an increase in the width and weight of the water being carried by each bucket. As with the pitchback design, the breastshot wheel uses the energy of the water twice as the waterwheel is designed to sit in the water allowing the waste water to help in the rotation of the wheel as it flows away down stream.

Generate Electricity using a Waterwheel

Historically water wheels have been used for milling flour, cereals and other such mechanical tasks. But water wheels can also be used for the generation of electricity, called a Hydro Power system.

By connecting an electrical generator to the waterwheels rotating shaft, either directly or indirectly using drive belts and pulleys, waterwheels can be used to generate power continuously 24 hours a day unlike solar energy. If the waterwheel is designed correctly, a small or “micro” hydroelectric system can produce enough electricity to power lighting and/or electrical appliances in an average home.

Look for Water wheel Generators designed to produce its optimum output at relatively low speeds. For small projects, a small DC motor can be used as a low-speed generator or an automotive alternator but these are designed to work at much higher speeds so some form of gearing may be required. A wind turbine generator makes an ideal waterwheel generator as it is designed for low speed, high output operation.

If there is a fairly fast flowing river or stream near to your home or garden which you can use, then a small scale hydro power system may be a better alternative to other forms of renewable energy sources such as “Wind Energy” or “Solar Energy” as it has a lot less visual impact. Also just like wind and solar energy, with a grid-connected small scale waterwheel designed generating system connected to the local utility grid, any electricity you generate but don’t use can be sold back to the electricity company.

In the next tutorial about Hydro Energy, we will look at the different types of turbines available which we could attach to our waterwheel design for hydro power generation. For more information about Waterwheel Design and how to generate your own electricity using the power of water, or obtain more hydro energy information about the various waterwheel designs available, or to explore the advantages and disadvantages of hydro energy, then Click Here to order your copy from Amazon today about the principles and construction of waterwheels which can be used for generating electricity.

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56 Comments already about “Waterwheel Design

    I wanna remove the engine and power with a water wheel.
    My stream is quite large and has a 2 foot water fall I can back flow a large constant flow from a resevior .
    How large of a wheel would be enough to replace the 8hp engine.
    4 feet tall and 20 inches wide be good?

    • The power output of your hydro system will depend on the type of generator (or alternator) used, which in turn depends on its rotational speed. Since the generated loaded voltage, and therefore its power output is proportional to the speed. Then once you know how fast your generator needs to rotate in revs-per-minute, you can back calculate the gearing or pulley ratio’s, their diameters, and type and size of waterwheel required for your particular location.

  • Outstanding information. Thank you!

    1 question regarding the feasibility, practicality and possibility:
    Can a waterwheel be used on the bank of my private springfed lake? Water moves accordingly with the wind. I would love to build a micro windmill to attach to the waterwheel for an added source for electricity and to power the waterwheel as well.

    • Waterwheels convert the kinetic energy of flowing or moving water into mechanical power which does the work to drive cogs, pulleys, pumps or generators, etc. Since a waterwheel consists of a series of paddles or boards attached to a central hub, it requires strong flowing water currents or a waterfall to drive it.

      Lakes are stationary bodies of water. Yes you are correct that the wind will move over the surface water to create ripples or swells, but the flow rate and therefore the hydraulic energy contained in the water will be very low and insufficient to drive a waterwheel or hydraulic turbine on its own. As you have stated, the movement of the water relies and the wind, and not the gravitational force of a river or chanelled water moving downhill.

      However, since the wind blows over the surface of the lake where the friction between the air and the water surface causes ripples, swells or even small waves. Maybe one of the many Wave Energy Devices available may be more suitable to your application.

  • Sir, thank you for the information provided on this site regarding the water wheels and their pictorial presentation. But, the diameter of the wheel and size of the buckets then how to design it for a particular type of flow, etc, should be mentioned separately.

  • We have several small rivers buried for over 150 years in many cases under our city, what options for micro hydro to be taken out?
    To pipe the head (40-50 m in many cases) would be expensive so I’m thinking about flow and low head options
    Wondering about axial flow turbines, but possibly with a bypass (like a turbofan jet) and 2-stage so that a high pressure feed can be taken out and through the generation element
    The other option might be to use a ram pump to feed an HP water bleed to the generating turbine, possibly with a headstock tank/reservoir local to the point of use
    Some of these rivers can also deliver cooling/heat transfer with heat pumps

    • None, as we doubt you can just extract water from beneath your city without permits or permissions. With a downward head of 40+ metres, the electrical consumption of one or more pumps may exceed the generated energy.

  • I am very much intrested in green energy, that can maintain our ecosystem. Iam doing some experiments in the same, I think we can produce huge amount of electricity fro our water sources. If I can get a chance I can do more.

  • Hello we are writing an article for our local paper about a water wheel on our hiking trail. May I use your overshot wheel schematic in the article? Thanks in advance

    • Hello. As you have kindly asked, we would have no objection to you using the information and/or images about overshot waterwheels from our website, free of charge.

      However, we must ask that you clearly and correctly reference, any images, information, or tutorials taken or copied from our Alternative Energy Tutorials website accordingly within all of your presentations.

  • Hi, I’m interested in purchasing a design manual of pentrough overshot water whel.
    Could you give me a hint where I vcan find it?

  • i found a variety of water turbines to convert presurized water or moving water to electricity.. And i dont like most of designs!! I got 2 small Qs:
    1st Q : can we use the axial gas turbine to run as water turbine ? ? And if not what are the reasons for such mismatch???
    2d Q: How come we can run the water pump as turbine without internal modification?? Adding capacitors for example??
    Thank you in advance!!

    • We assume that Axial flow gas turbines use multiple blades more as a compressor, but as we have no experience with gas turbines, so can not comment further.

      There are many different types of water pumps which can be used in a microhydro turbine application as manufacturers also test their pumps in turbine mode. The torque produced from the output shaft of a pump-as-a-turbine is converted into electricity by use of a DC or AC generator, whatever is connected to the shaft.

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