Mechanical toys depend on using the four basic kinds of movement and converting one type to another (or more than one other).  You will remember from earlier tasks and from science work that movement is classed into :

…. and as far as  toys are concerned the fun is that a rotating handle makes something different happen as the output.  Traditional toy makes created toys to entertain their patrons.

This arrangements of gears is moving the rotation through 90 degrees - Our contact is with a friction drive rather than the bevelled gears shown here.-
and by covering the surfaces in contact with each
other with glass-paper, an even better 'friction surface' is achieved.

Whilst looking at gears notice that the direction of
rotation is also reversed when two gears are in