Cogwheel (Gear)

Teeth - set the number of teeth or cogs.

Pitch Radius - set the radius from the centre to the midpoint of the tooth.

Hole Radius - set the radius of the hole.

Tooth Depth - set values for the Addendum (the top of the tooth) and the Dedendum (the bottom of the tooth)

Tooth Taper - set taper angles for the Addendum and Dedendum.

Gear Example

All rotation is driven by the medium Cogwheel.

In order to create a gear system there are some basic guides to follow:

  • The Module of each Cogwheel must match. The module is a ratio which can be easily expressed as:

    • pitch diameter / the number of teeth. Or in Cavalry's case:

    • 2 * Pitch Radius / Teeth.

  • The teeth must be the same shape/size.

  • The Pitch Circle of one Cogwheel must 'touch' the other.

In the example below:

  • the Medium Cogwheel has a Pitch Radius of 200 and 12 Teeth.

  • the Small Cogwheel has a Pitch Radius of 100 and 6 Teeth.

  • the Large Cogwheel has a Pitch Radius of 400 and 24 Teeth.

200 / 12, 100 / 6 and 400 / 24 all equal 16.66 so each Cogwheel has the same Module.

The math for the rotation is also quite simple. If:

  • r1 = Rotation of the Medium Cogwheel

  • t1 = Number of Teeth of the Medium Cogwheel

  • r2 = Rotation of the Small Cogwheel

  • t2 = Number of Teeth of the Small Cogwheel

r2=r1t1/t2r2 = r1 * t1 / t2

so in the case of Medium > Small that would be:

r2=r112/6r2 = r1 * 12/6

You can use a Jsmath Atom to rig this equation up.

  1. Create a Jsmath Atom.

  2. Add 3 indices.

  3. Connect Medium.rotation > jsmath.index0

  4. Connect Medium.teeth > jsmath.index1

  5. Connect Small.teeth > jsmath.index2

  6. Connect > Small.rotation

As you rotate the Medium Cogwheel, the Small Cogwheel will rotate at the correct speed to mesh. In order to position them correctly you'll need to move them 300 apart in X (the total of their Pitch Radius values).