Symbol for car brakes

Question

Symbols that have to do with the brakes of a car, from dashboard indicators to the sticker on the braking fluid reservoir, all have a common theme of a circle surrounded by two curved lines. From this website:

I would like to draw the first symbol (black on white), but can't find the Unicode character for it. DeTeXify also doesn't know it. How do I draw this simple figure inline with \tikz{ }?

Bonus points if you can recreate the other symbols without the size of the circle changing. For the symbol with dashed lines, it'd be interesting to know how to get three dashes consistently, rather than relying on TikZ's default of not caring about one endpoint.

---

Edit: For what it's worth, here's a snippet that can be used to test whether your solution affects the whitespace around the current line.

\documentclass[11pt]{article}
\usepackage{tikz}

\begin{document}

\noindent This is the first line.\\
The brake symbol \tikz{ ??? } can be found on your dashboard.\\
This is the third line.\\
This is the fourth line.

\end{document}

Answer 1

Here is a macro \brake[<tikz styles>]{content} that will produce your symbols. The <tikz styles> are optional but can include color, line patterns, etc. The height of the symbols can be adjusted by changing \newcommand{\brakeheight}{3mm}.

\documentclass{article}

\usepackage{tikz}

\newcommand{\brakeheight}{3mm} % height of symbols
\newcommand{\brake}[2][]{\tikz[font=\sffamily]{
    \draw[#1, solid] circle[radius=.5*\brakeheight];
    \draw[line cap=round, #1] (-45:.6*\brakeheight)arc(-45:45:.6*\brakeheight) (135:.6*\brakeheight)arc(135:225:.6*\brakeheight);
    \node[#1, inner sep=0pt, scale={.85*\brakeheight/max(width("#2"), height("#2"), 1)}]{#2}
}}

\begin{document}

Previous line.

Inline \brake{!} \brake[orange]{ABS} \brake{} \brake[dash pattern=on 2pt off 1pt]{} symbols.

Following line.

\end{document}

Answer 2

Using the heatmark shape from the ext.shapes.heatmark library of my tikz-ext package we can recreate these symbols with two tweaks.

The lightning symbol is taken from the marvosym package, the show symbol is from twoemojis. Maybe you can find a better symbol somewhere. If needed, we could put a separate drawing inside the symbol but I don't want to find a shoe path now.

---

For now, the symbols are sized acoording to the inner sep of 0.15em and a content of AAA in the font \sffamily (see node font as well as the text … keys inside the definition of mew/brake symbol).

The !, ↯ and 👟 are sized manually and will ignore any font setting of the node or the text outside of TikZ. Depending on your use-case, we will have to find a more flexible solution.

Code

\documentclass[varwidth]{standalone}
\usepackage{tikz, marvosym, twemojis}
\usetikzlibrary{ext.shapes.heatmark}
\pgfset{% a few hacks
  no quick fill/.code=\def\pgfusepathqfill{\pgfusepath{fill}},
  no fill/.code=\def\pgfusepathqfill{\pgfusepath{}}}
\tikzset{
  mew/brake symbol/.style={
    shape=heatmark, draw, line width={#1}, inner sep=+.15em, outer sep=+0pt,
    heatmark arcs=2, heatmark arc width={#1}, heatmark arc sep={#1},
    heatmark arc rings=1, heatmark arc sep angle=90,
    heatmark inner opacity=1, heatmark outer opacity=1,
    /pgf/heatmark ring 1/.append style={% needs /pgf/
      no quick fill, /tikz/rounded corners={(#1)/2}},% needs /tikz/
    node font=\sffamily, align=center,
    text width=width("AAA"), text height=height("A"), text depth=+0pt},
  mew/brake symbol/.default=1.5pt,
  mew/use brake symbol/.cd, .is choice,
  empty/.style={mew/brake symbol, node contents=},
  ESP/.style  ={mew/brake symbol, node contents=ESP},
  ABS/.style  ={mew/brake symbol, node contents=ABS},
  RBS/.style  ={mew/brake symbol, node contents=RBS},
  !/.style    ={mew/brake symbol, node contents=\raisebox{-.5ex}{\bfseries\LARGE!}},
  lightning/.style={mew/brake symbol,
    node contents=\raisebox{-.6ex}{\bfseries\LARGE\Lightning}},
  shoe/.style     ={mew/brake symbol,
    node contents=\raisebox{1.9ex}{\rotatebox{-80}
      {\scalebox{-1.8}[1.8]{\twemoji{man’s shoe}}}}},
  hand brake/.style={
    mew/brake symbol, node contents=,
    heatmark arcs=12, heatmark arc sep angle=6,
    /utils/mew/no heatmark arc/.list={3, 4, 5, 9, 10, 11}},
  /utils/mew/no heatmark arc/.style={/pgf/heatmark arc #1/.append style=no fill}}
\newcommand*\brakesymbol[2][]{%
  \tikz[baseline, trim left=(@.west), trim right=(@.east)]
    \node(@)[anchor=base,mew/use brake symbol={#2},#1];}
\begin{document}
\foreach \Type in {empty, ESP, ABS, RBS, !, hand brake, lightning, shoe}{%
  \Type: \brakesymbol{\Type}\par}
\end{document}

Output

Answer 3

A minimal solution that doesn't support content inside the circle nor three-dash arcs, inspired by Qrrbrbirlbel's comment (with different arc radii and with downscaling for inline use):

\documentclass[11pt]{article}
\usepackage{tikz}

\newcommand{\brake}{\hspace{-0.5pt}\tikz[scale=0.15,baseline=-0.3em]{\draw[delta angle=90] (0,0) circle[radius=1] (-45:1.35) arc[start angle=-45, radius=1.35] (135:1.35) arc[start angle=135, radius=1.35];}}

\begin{document}

\noindent This is the first line.\\
The brake symbol \brake{} can be found on your dashboard.\\
This is the third line.\\
This is the fourth line.

\end{document}

Output: