**Contents**show

## How do you model a spur gear?

**Best Modeling of Spur Gear**

- Step 1: start with Sketch.
- Step 2: use offset command.
- Step 3: create tooth line and give dimension.
- Step 4: Apply fillet like this.
- Step 5: use circular pattern.
- Step 6: use trim (power)
- Step 7: Extrude.
- Step 8: sketch on left face and use cut extrude.

## How do you make a gear in CAD?

**How do you use CAD gears?**

- Start AutoCAD.
- Make 2 circles.
- Make the profile of the gear tooth spaces.
- Trim the circles side ways.
- Now enter “bo” command. It will show the boundary creation dialogue. …
- Click inside the region and then press enter.
- Now we have the polyline created. …
- Make a circle of 50mm radius.

## How do you design a gear?

For design of gears, determine elements such as size, tooth shape, pitch, number of teeth, amount of profile shift, material, need for **heat treating and/**or grinding, choice for kind of tooth surface finish, amount of backlash, helix angle, helix direction, method of mounting on shaft, precision class, etc., the …

## What is gear module formula?

In general, the size of a gear tooth is expressed as its module. … By the way, the pitch circle diameter of a spur gear (d) can be obtained by multiplying the module (m) and the number of teeth (z). Expressed as a formula, it is **d = m x z**.

## What is the diametral pitch of a gear?

The diametral pitch of a gear is **the number of teeth in the gear for each inch of pitch diameter**. Therefore, the diametral pitch determines the size of the gear tooth.

## How do you draw a gear profile?

Unwin’s Construction is a way to draw an approximation to an involute gear profile.

…

- Draw the pitch circle, diameter D, about the centre of the gear, O. …
- Draw the outside diameter (green) by drawing a circle about O with a radius greater than the pitch circle by the value of the addendum.

## At what speed should you change gears?

What Speed Should You Change Gears?

Gear | Speed |
---|---|

1st gear | Between 0 mph and 10 mph |

2nd gear | Between 10 mph and 20 mph |

3rd gear | Between 20 mph and 30 mph |

4th gear | Between 30 mph and 40 mph |

## How is gear ratio calculated?

To calculate the gear ratio:

**Divide the number of driven gear teeth by the number of drive gear teeth**. In our example, it’s 28/21 or 4 : 3. This gear ratio shows that the smaller driver gear must turn 1,3 times to get the larger driven gear to make one complete turn.

## What is the Lewis equation?

The Lewis equation indicates that **tooth bending stress varies** (1) directly with load , (2) inversely with tooth width b, (3) inversely with tooth size p or m, (4) inversely with tooth shape factor y or Y. Drawbacks of Lewis equation are: 1. The tooth load in practice is not static.