Ever wondered: Why doesn’t a bicycle move backwards when one pedals back?

Ratchet mechanism is commonly used in bicycles, tricycles, Engine starters, Socket wrenches etc. 


A ratchet mechanism is one which allows rotation in one direction only direction while preventing motion in the opposite direction.

To know more check out this: https://en.wikipedia.org/wiki/Ratchet_(device)

Materials Required:

1×1 feet – Hylam sheet 6mm thick.

M4x20 bolts

M4 Nuts

Rubber band or spring



  1. A ratchet featuring gear
  2. pawl
  3. mounted on base


  1. Using a CNC router cut out the required parts as shown in the image. The names of the individual parts are shown in the figure, use them as reference for the following steps.
  2. Download the .dxf files for the ratchet mechanism HERE
  3. Assemble the parts as shown in the figure and fix then using fasteners
  4. Use either a rubber band or a spring to tension the pawl such that it always forces itself on the ratchet gear.
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