Change direction: When two gears mesh together, the second one always turns in the opposite direction. So if the first one turns clockwise, the second one must turn counterclockwise. You can also use specially shaped gears to make the power of a machine turn through an angle.

#### How are gears used to change speed?

Gears are used to increase or decrease the speed or power of rotary motion. This is equal to the number of teeth on the driver gear divided by the number of teeth on the driven gear. To decrease the speed of the output, the driver gear is smaller than the driven gear.

### What speed is 2nd gear?

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 do gears turn 90 degrees?

Bevel gears that have pitch angles of exactly 90 degrees have teeth that point outward parallel with the axis and resemble the points on a crown. That’s why this type of bevel gear is called a crown gear. Mitre gears are mating bevel gears with equal numbers of teeth and with axes at right angles.

## What mechanism increases speed and decreases torque?

The bevel gear is used to change rotational motion at a 90˚ angle. Using gears with differing numbers of teeth will change the speed and torque.

### How are gears used to change the direction of motion?

Draw a big colorful dot on each gear, and position the gears so that both dots are at the top. As you turn the big gear, have one person count how many times the big gear turns all the way around and another person count how many times the small gear does. Do they turn the same number of times? Gears work to change the direction of motion.

#### What happens when you turn a gear one way?

When you turned the big gear one way, the little gear turned the other way! Gears also change speed of motion. When you turn the big gear slowly, the smaller gear turns faster. This helps save energy, because you don’t have to work as hard to turn the big one slowly as if you had to turn the small one quickly.

### How does the rotation of the driving shaft work?

The rotation of the driving shaft (and the driving gear) is in the opposite direction to that of the driven shaft (and driven gear), and the efficiency of power and motion transmission is typically high.

### How does the second wheel in a pair of gears work?

Increase force: If the second wheel in a pair of gears has more teeth than the first one (that is, if it’s a larger wheel), it turns slower than the first one but with more force. (Turn the blue wheel and the red wheel goes slower but has more force.)