Trundle wheel

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The Trundle wheel is a measuring device, a simplified form of a surveyor's wheel. It is commonly used by school children who need an easy way to find the rough distance from one place to another. The trundle wheel is comprised of a wheel, a handle which is attached to the axle allowing the trundle wheel to be held easily, and a clicking device which is triggered once per revolution of the wheel. Trundle wheels are not as accurate as other methods of measuring distance but are a good way to get a rough estimation of a fairly long distance over a good surface.

[edit] How the trundle wheel works

The trundle wheel works by having a wheel which has a circumference of exactly 1 metre, hence one revolution of the wheel equates to 1 metre of distance traveled on the ground if there is no slip. Every time the wheel makes a rotation the wheel produces an audible click which is then counted and therefore the number of clicks that counted by the user is approximately the number of meters traveled. Due to the design of the trundle wheel it is not always moved in a straight line and this inevitably adds on extra distance to the final reading.