# Drivetrains
Drivetrains

A **drivetrain** is the moving base of a robot. It includes the wheels, motors, gears, and frame that let the robot travel around the field. Picking the right drivetrain is one of the most important decisions your team makes — it affects how fast, how strong, and how maneuverable your robot will be.

There are four common drivetrain types in VEX robotics:
- Tank Drive
- Mecanum Drive
- X-Drive
- H-Drive

**Why does this matter?**

The drivetrain you choose shapes every other decision on the robot. A slow, powerful drivetrain suits pushing matches. A fast, agile drivetrain suits games that require quick movement and precise positioning.

**Tank Drive**

Tank Drive is the most classic and simple drivetrain. The left wheels are controlled by one set of motors, and the right wheels are controlled by another set — just like the tracks on a military tank!

![Tank Drive Drivetrain](/images/Diagrams/TankDriveDrivetrain.jpg)

- **How it moves:** To go straight, both sides spin forward together. To turn, one side spins forward while the other spins backward.
- **Pros:** Great traction and pushing power. Hard for opponents to shove around. Also easy to build and easy to code.
- **Cons:** Cannot slide directly sideways — it must turn to change direction.

**Mecanum Drive**

Mecanum Drive uses 4 special **mecanum wheels**. These wheels have small rollers attached at a 45-degree angle around the rim. By spinning the four wheels in different combinations, the forces cancel out in certain directions and push the robot sideways!

![Mecanum Drive Drivetrain](/images/Diagrams/MecanumDriveDrivetrain.jpg)

![Mecanum Drive Diagram](/images/Diagrams/MecanumDiagram.jpg)

- **How it moves:** Spin all four wheels in specific combos to move in any direction — forward, backward, left, right, and diagonally — without turning the robot.
- **Pros:** Very agile. Great for quickly lining up with a goal or game piece.
- **Cons:** More complex to code, and the 45-degree angle means some pushing force is wasted — it cannot push as hard as a tank drive.

**X-Drive**

An X-Drive uses four regular omni wheels, but each wheel is pointed outward at a 45-degree angle, making the robot look like the letter "X" from above.

![X-Drive Drivetrain](/images/Diagrams/X-DriveDrivetrain.jpg)

- **How it moves:** Like mecanum drive, it can move in any direction by combining different wheel speeds.
- **Pros:** Extremely fast — about 1.41 times faster than tank drive using the same motors! Also very agile and great at turning quickly.
- **Cons:** Complicated to build correctly (must be a perfect square), and has low pushing power because the force is split between directions.

**H-Drive**

H-Drive looks like a normal tank drive, but with one or two extra wheels mounted sideways in the center of the robot. From above, it looks like the letter "H."

![H-Drive Diagram](/images/Diagrams/H-DriveDrivetrain.jpg)

- **How it moves:** The outer wheels handle forward, backward, and turning like a normal tank drive. The center sideways wheel is controlled by a separate motor and handles sliding left and right.
- **Pros:** Simpler to code than X-Drive or Mecanum. Keeps full tank drive pushing power when going forward, but can still slide sideways.
- **Cons:** If the field is slightly uneven, the center wheel may lose contact with the ground and stop working. Also requires an extra motor just for the center wheel.

| **Drivetrain Style** | **Agile** | **Pushing Power** | **Speed** | **Complexity** |
| -------- | -------- | -------- | -------- | -------- |
| Tank | :x: | :green_circle: Very high | :yellow_circle: Medium | :green_circle: Easy |
| Mecanum | :heavy_check_mark: | :red_circle: Low | :yellow_circle: Medium | :yellow_circle: Medium |
| X-Drive| :heavy_check_mark: | :red_circle: Very Low | :green_circle: Very High | :red_circle: Hard |
| H-Drive | :heavy_check_mark: | :green_circle: High (Forward) | :yellow_circle: Medium | :yellow_circle: Medium |

Each drivetrain type needs different code and controls to drive well. Make sure your programming matches your drivetrain choice!