In automotive engineering, the master cylinder is a control device that converts non-hydraulic pressure (commonly from a driver's foot) into hydraulic pressure. This device controls slave cylinders located at the other end of the hydraulic system.

The master cylinders are the first products manufactured by SAFIM.

Today is available a wide variety of master cylinders:
- With and without booster
- Displacement from 8 to 67 cm³
- Single and step-bore
- Single, double and twin circuits
- For mineral oil or brake fluid (DOT4)