# Motors
Motors convert electrical power into rotating mechanical energy. There are multiple types of motors, including brushed, brushless, and stepper motors. Most active mechanisms on FTC robots use motors to provide motion.
### Motor Selection
Choosing the right motor for your application requires understanding the balance between **speed**, **torque**, **power output**, and **gear reduction**. There’s no one-size-fits-all motor—each use case demands careful matching of motor characteristics to the mechanical load.
#### Gearboxes: Amplifying Torque or Speed
Most FTC motors come with **pre-installed gearboxes** that affect output in two key ways:
* **High gear ratio = Low speed, High torque**
* **Low gear ratio = High speed, Low torque**
For example:
* A motor with a **19.2:1 gearbox** will turn slowly but provide strong torque—great for lifting heavy arms or driving slides.
* A motor with a **5.2:1 gearbox** spins faster with less torque—better for wheels or shooters.
{% hint style="info" %}
*Tip: Check the stall torque and free speed in the motor datasheet before deciding.*
{% endhint %}
Legal FTC Motors
### How to Calculate Torque and Speed
Motor **power output** is a measure of how much work the motor can do per unit time, and is defined as:
```markdown
Calculating Motor Power, Torque, and Gear Reduction
Given:
- Voltage: 12V
- Current: 9A
- Free Speed: 6000 RPM
- Efficiency: ~75%
1. Input Power
Electrical power = V × I = 12V × 9A = 108W
Mechanical output = 108W × 0.75 = 81W
2. Free Speed Torque
Convert RPM to rad/s:
6000 RPM × 2π / 60 = 628.3 rad/s
Use: P = τ × ω
So: τ = P / ω = 81 / 628.3 ≈ 0.129 Nm
3. Gearbox Effect (Example: 20:1 reduction)
- Speed: 6000 / 20 = 300 RPM = 31.42 rad/s
- Torque: 0.129 × 20 = 2.58 Nm
- Power stays the same: 2.58 × 31.42 ≈ 81W
Gearing doesn't create power—it **trades** speed for torque (or vice versa).
Use gear ratios to match motor output to what your mechanism actually needs.
```
{% hint style="danger" %}
## COMING SOON: Motor Power Calculator
{% endhint %}
### Torque vs Speed
Every motor has a **performance curve**. At one end is **maximum torque at zero speed** (stall torque), and at the other is **maximum speed at zero torque** (free speed). In between is the **power peak**—the point where the motor is doing the most work.
When designing a mechanism:
* **Too much torque = Slow and inefficient**
* **Too much speed = Can’t move the load**
The **ideal balance** happens when you operate near the motor's peak power, which is around **50% of its stall torque** and **50% of its free speed**.
GoBILDA Planetary Gearbox
| Mechanism Type | Needs More... | Gearbox Recommendation |
| -------------- | ------------- | -------------------------------- |
| Arm or Lift | Torque | High ratio (e.g., 19.2:1, 26:1) |
| Flywheel | Speed | Low ratio (e.g., 5.2:1) |
| Drivetrain | Balanced | Mid ratio (e.g., 13.7:1 or 20:1) |
{% hint style="info" %}
*Rule of Thumb:* If a motor is getting hot or stalling, you probably need more gear reduction. If it’s spinning super fast but not moving anything, increase the load or reduce gear reduction.
{% endhint %}
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