> For the complete documentation index, see [llms.txt](https://docs.andymark.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.andymark.com/robits-build/getting-started/mobility/ftc-actuators.md).
# FTC Actuators
Actuators are the components that make a robot move. In the Robits system, motor and servo options can be used to power drive systems and mechanisms.
Motors are generally used when continuous rotation or higher power is needed. Servos are useful when a mechanism needs controlled positioning or when a smaller, lighter actuator is easier to use.
The Robits system is designed around common components and mounting patterns, making it possible to connect actuators to the rest of the robot without creating complicated custom structures.
### Motors
[NeveRest Hex Gearmotors](https://andymark.com/products/neverest-hex-gearmotors) are the primary motor used with Robits. They are gearmotors, meaning that a motor is combined with a gearbox to provide a useful balance of speed and torque. The gear ratio determines how the motor's speed and torque are changed at the output shaft.
A higher gear reduction generally provides more output torque at lower output speed, for better ability to lift heavier loads. A lower gear reduction generally provides a higher output speed with a lower output torque for overall faster movement.
The correct motor depends on what the mechanism needs to do. A fast mechanism with a light load may benefit from a lower gear ratio, while a mechanism that needs to lift or move a heavier load may need more reduction.
### Motor Output
Robits uses 3/8 inch hex shafts for transferring motion. NeveRest Hex motors have a 3/8 hex output that can be connected to gears, wheels, pulleys, and other motion components.
When connecting a motor to a Robits mechanism, the motor can be attached using an appropriate Robits [motor mount](/robits-build/getting-started/mobility/carriers-and-mounting-brackets.md) or gearbox. The Robits mounting system makes it easy to change the motor mounting and gear arrangement as the robot develops with different motors, carriers, and mounting brackets.
***
### Servos
[Servos](https://andymark.com/products/programmable-servos) can be connected to Robits structure directly using the grid holes on the flange and can be adapted to 3/8 inch hex using an [adapter](https://andymark.com/products/5-mm-hex-to-hex-adapter?variant=44493458899116). Unlike a typical motor, a servo is designed to move to a commanded position or operate according to a controlled motion range. AndyMark programmable servos can also be controlled in "continuous rotation mode" if an application requires a continuously rotating servo.
Servos are useful for mechanisms that require small movements with a lightweight source of power. Examples include moving a small arm, opening or closing a claw, changing the position of a linkage, or a place where you need power further away from your center of gravity.
Both the programmable torque servos and programmable speed servos are included in the Robits Core Kit.
***
### Motors vs. Servos
| Motors | Servos |
| ------------------------------------------- | ------------------------------------------------------ |
| Good for continuous rotation | Good for controlled positioning |
| Available with different gear ratios | Available in different torque and speed configurations |
| Commonly used for drive, lifts, and intakes | Commonly used for rollers, claws, and linkages |
Neither type of actuator is automatically better. The correct choice depends on the mechanism being designed.
