Activity 113 Gears VEXIntroductionYou Do Not
Activity 1.1.3 Gears - VEX
Introduction
You do not have to look far to see gears. You might not think of an object such as a computer as having a lot of moving parts, but the CD tray on your computer is likely controlled by gears. A traditional watch is full of gears. The watch has one source of power or input that must move multiple hands continuously and at different speeds. Some watches also keep track of the day of the month. This may be low-tech by today’s standards, but imagine the challenge of choosing just the right gears to keep a watch synchronized. In a watch the gears are used to manipulate rotational speed. Gears are also used in many applications to control torque and rotational direction.
Equipment
VEX POE kit gears and support pieces
Calculator
Procedure
In this activity you will learn about gear ratios and how they affect speed and torque within a system. You will also construct simple and compound gear systems.
Functions of Gears
Gears change the speed of rotation.
Gears change the direction of rotation.
Gears change torque values.
Gear Ratios
By joining together two or more gears of different sizes, both the speed and the torque are changed from the input gear to the output gear. The larger gear within a system will always move slower and have more torque than the smaller gear. Gear Ratio (GR) is a comparison between the driver gear, also called the input (connected to the power source), and the gear being driven, or the output. Below are four ways to determine the gear ratio in figure 1.
Method 1: The gear ratio can be determined by counting the number of teeth on each gear. The ratio is expressed by dividing the number of teeth on the output gear (nout) by the number of teeth on the input gear (nin).
Gear ratios are often expressed using a colon. In this example the ratio is 2:1 (pronounced two to one). The gear ratio of 2:1 indicates that the driver gear is half the size of the driven gear, and that the driver gear will make two
Introduction
You do not have to look far to see gears. You might not think of an object such as a computer as having a lot of moving parts, but the CD tray on your computer is likely controlled by gears. A traditional watch is full of gears. The watch has one source of power or input that must move multiple hands continuously and at different speeds. Some watches also keep track of the day of the month. This may be low-tech by today’s standards, but imagine the challenge of choosing just the right gears to keep a watch synchronized. In a watch the gears are used to manipulate rotational speed. Gears are also used in many applications to control torque and rotational direction.
Equipment
VEX POE kit gears and support pieces
Calculator
Procedure
In this activity you will learn about gear ratios and how they affect speed and torque within a system. You will also construct simple and compound gear systems.
Functions of Gears
Gears change the speed of rotation.
Gears change the direction of rotation.
Gears change torque values.
Gear Ratios
By joining together two or more gears of different sizes, both the speed and the torque are changed from the input gear to the output gear. The larger gear within a system will always move slower and have more torque than the smaller gear. Gear Ratio (GR) is a comparison between the driver gear, also called the input (connected to the power source), and the gear being driven, or the output. Below are four ways to determine the gear ratio in figure 1.
Method 1: The gear ratio can be determined by counting the number of teeth on each gear. The ratio is expressed by dividing the number of teeth on the output gear (nout) by the number of teeth on the input gear (nin).
Gear ratios are often expressed using a colon. In this example the ratio is 2:1 (pronounced two to one). The gear ratio of 2:1 indicates that the driver gear is half the size of the driven gear, and that the driver gear will make two