Background Technical Report: Snowman on Skis
Johnny Ngo
ME 2331.03 Introduction to Design
Carlos Castro
9/6/2023
Introduction
The object of this report is a windup toy with the appearance of a snowman, by twisting
the key of the toy it begins to move around in circles or semi circles. The toy is made out of
plastic and some metal parts such as screws and a rod. Some requirements the toy might have
had when it was being produced was a simple to understand mechanism to make playing with
easier for children. Size must have also been taken into account because children are prone to
putting objects into their mouths which chokes the child. The purpose of this report is to figure
out how the toy works and provide a plausible theory on how it works before disassembly.
Team’s Preliminary Ideas
We believed that the toy uses gears and upon winding it up the energy was transferred
to a large main gear, that then connects to another gear with an axle that powers the rocking
motion needed by the toy to move in a curved fashion, denoted by the reverse D in figure 1.
This axle also connects to another gear that powers the wheels which allows forward
movement by the toy.
Figure 1 Internal View
The shell around the internals is fashioned to look like a snowman on skis which is held together
by two screws (Figure 2). The internals are protected by a shell of plastic which is then attached
Figure 2 Back View
by a rod to the shell allowing the rocking motion to take place denoted by the pivot point in
Figure 3. The snowman shell for the internals can also be seen from the side from Figure 4.
Figure 3 Bottom View
Figure 4 Side View
Background Research
A windup toy works through gears and springs, moving parts as opposed to electronics
which are mostly static. By turning the wind-up of the toy a spring, called a mainspring, is
compressed storing the energy and when the wind-up is released a gear attached to the spring
uses this energy to power the other mechanisms of the toy [1]. The Snowman is likely powered
by this mechanism. The rocking motion from this is most likely caused by a rocking gear system
that controls the tilt of the snowman [2].
Preliminary Updated Ideas
The windup mechanism now includes a tensile spring that allows the storage of energy
rather than assuming that energy was somehow magically stored in the gear system. An extra
axle with gears was added to the top to attach to a rocking gear mechanism that might use a
cam to create the rocking motion. The mechanisms used to move the wheels are still the same
as before.
References
[1]Woodford, Chris. (2010/2022) Clockwork (windup) mechanisms. Retrieved from
https://www.explainthatstuff.com/how-clockwork-works.html. [Accessed 9/5/2023]
[2] thang010146. “Two rocker mechanism with bevel gears,” Youtube Video, 0:20, posted by
“thang010146,” October 26, 2013, https://www.youtube.com/watch?v=zv-yK7XECYE