I created this model for two reasons:
(1) a colleague of mine needed the video for his mechanical engineering lecture
(2) my research relies heavily on SimMechanics, so I wanted to gain more experience

The model shows a motor that drives a shaft. A spur gear is attached to the drive shaft, which meshes with a larger gear on the driven shaft. Also attached to the driven shaft is a fan.

There are many ways to modify the model parameters:
(1) The recommended approach is to open the Model Explorer, navigate to the Model Workspace of the given file, and edit the MATLAB Code provided. Parameters include part dimensions, input angular velocity, colors, and opacity.
(2) You can also edit parameters directly through the subsystem masks by clicking on a part in the model. However, be aware that some parameters are used in more than one place (e.g. motor box length is used to compute the y-offset in the Rigid Transform block), hence why I set parameters via MATLAB Code in the Model Workspace.