How to Make Your Car Last Forever: Avoid Expensive Repairs, Improve Fuel Economy, Understand Your Warranty, Save Money

In the illustration above we see a typical brake master cylinder setup. Note that the reservoir has caps on it.
This is where the unit is filled with brake fluid. In the cutaway view we see the inner workings of the master
cylinder. We have a primary and secondary piston, the primary providing hydraulic pressure to the front brakes
and the secondary the rear.