A Multi-use Pedal-powered Engine

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Human legs are generally much stronger than the arms and can sustain an effort for a longer time.  Therefore, a pedal-powered engine that can be adapted to different machines is extremely useful in rural areas without access to electrical energy.

A local youth, Merlin Yafeth Cerrato Ardon, and I decided to construct such an engine from a junked mountain bike.  Various parts of the bicycle had already been salvaged, but the frame and drive train were still intact and were adequate for our needs. 

Yafeth had learned to weld and use other metal-working tools in his industrial arts class in school and was eager to test his skills on a useful project.

We began by making a base for the bicycle frame out of one-inch galvanized electrical conduit.

With the front fork removed, we welded the bicycle frame to the base in an inverted position so that its rear axle would be in front of the operator. 

The chain drives a shaft with V-belt pulleys on both ends.  The perforated angle-iron allows different devices to be attached in different positions.  

Since there is no need to shift gears on the fly, the sprocket combination can be adjusted for each implement by tightening or loosening the nut on the eye-bolt connected to the chain shifter. 

We did not need or want the free-wheeling axel, so both chains link to different sprockets on the same cassette.  Three sprockets are used for the chain from the pedals, and three are used for the chain driving the pulley shaft. 

Here we are attaching a grain mill to the engine.  

The grain mill in operation

Depulping coffee

Modification

 

We found that the grain mill would become jammed periodically and had to be backed up a turn or two to free it.  Despite wiring the rear derailleur in a fixed position, there was still enough play in it to cause the chain to slip several cogs when it was reversed.  We then removed the rear derailleur completely and replaced it with the rear hub and sprocket from a salvaged child’s bicycle.  

Different sprockets can be selected by moving the axel right or left along the perforated angle iron, and the tension on the chain can be adjusted by adjusting the four bolts up or down.