# Motor

> Component kind `motor` (category `mech`, DSL name `motor`, API v1)

Rotational source. Produces a constant RPM on its axis port every tick; connecting a shaft or gear via `mech.couple` / `mech.mesh` drives the downstream chain.

## Parameters

- **`rpm`** — Rotational speed at the axis port (RPM). Signed — negative spins the other way.
- **`bodyLength`** — Motor body length along Z (mm, visual only).
- **`bodyDiameter`** — Motor body diameter (mm, visual only).
- **`shaftLength`** — Output shaft length sticking out of the body (mm, visual only).
- **`shaftDiameter`** — Output shaft diameter (mm, visual only).

## Parameters schema

| Parameter | Type | Default | Constraints |
| --- | --- | --- | --- |
| `rpm` | Number | 30 |  |
| `bodyLength` | Number | 40 |  |
| `bodyDiameter` | Number | 30 |  |
| `shaftLength` | Number | 15 |  |
| `shaftDiameter` | Number | 8 |  |
| `color` | String | — |  |

## Ports

| Port | Type | Description |
| --- | --- | --- |
| `axis` | `rotational` | Rotational output. The motor seeds this port every tick. |

## Kinematics

Source. Auto-registers a driver with `{ rpm: params.rpm }` on the axis port — no `mech.drive(...)` needed.

## Example

```
motor "M1" {
  rpm: 60
  at: position(0, 0, -50)
}
```