Pedal Power Dynapod
A dynapod is a stationary pedal-powered device. The word ‘Dynapod’ comes from the Greek words for power and foot. The dynapod can be attached to any kind of device or tool and used to generate power for a multitude of activities. The first design for this type of unit was introduced in 1968.
Although it was not built, Alex Weir (Edinburgh University) built one and two person dynapods at Dar-es-Salaam in Tanzania. An cement-filled bicycle wheel was used as a flywheel. He developed and built many prototype units using square tubing for the framework. His prototype inventions were tested as corn grinders and a winnowing machine.
There are seemingly endless possibilities for pedal power tools. The list is long: Hand-driven machines, grinders, forge blowers, pumps, pottery wheels and drilling machines are just a few. The image to the left shows a commercial maize sheller, powered by a bolt-on dynapod unit. This particular unit can shell two maize cobs at one time, and has been sold in some African countries. The work is done by a heavy cast-iron fan, which acts as both a winnower to clear away husks, and a flywheel.
While pedal power is a great form of generating torque, there are some problems. Cyclic torque is one problem, another is rigidity. The pull of the chain can be as much as twice the rider’s weight, so a sturdy strut is needed between the driving and driven chain (see prototype image at right). The chain must also have some sort of adjustment mechanism in order to take up the slack. An obvious necessity is the need to keep the operator cool while they are pedaling. The Chinese use a simple canopy to protect the person from sun and rain. A small portion of the power generated could also be used to power a small cooling fan.
Source: Pedal Power News
McCullagh, James C., ed. Pedal Power: In Work, Leisure, and Transportation. Emmaus: Rodale Press, 1977. ISBN: 0-87857-178-7