I'm trying to align an equation in two points, my code is the following:

```
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
\begin{cases}
\omega_W \geq \omega_{W0} \hspace{2mm} &\Leftrightarrow \hspace{2mm} S_x \rightarrow \infty & \longrightarrow \text{Wheel is spinning} \\
\omega_W > \omega_{W0} \hspace{2mm} &\Leftrightarrow \hspace{2mm} S_x > 0 & \longrightarrow \text{Tire driving force} (F_x >0) \\
\omega_W = \omega_{W0} \hspace{2mm} &\Leftrightarrow \hspace{2mm} S_x =0 & \longrightarrow \text{Free-rolling tire} (F_x=0) \\
\omega_W \leq \omega_{W0} \hspace{2mm} &\Leftrightarrow \hspace{2mm} S_x < 0 & \longrightarrow \text{Tire braking force} (F_x <0) \\
\omega_W =0 \hspace{2mm} &\Leftrightarrow \hspace{2mm} S_x= -1 & \longrightarrow \text{Wheel lock-up} \\
\end{cases}
\end{equation}
\end{document}
```

The thing is that I want an alignment in "Leftrightarrow" and in "longrightarrow". However, the output I'm getting is the following (and of course the error of "extra alignment tab has been changed to \cr"):

Any idea about why it's not working, or how can I fix it? I wrote all the `\\`

and also I added the `&`

in the points I want to get an alignment.

## Best Answer

`cases`

only accepts one`&`

per row. You can easily emulate it with`array`

. The`r>{{}}l`

trick is for obtaining the correct spacing around the relation symbols. I removed the long arrows, which I find redundant.