Definition of a Function. A function is a relation for which each value from the set the first components of the ordered pairs is associated with exactly one value from the set of second components of the ordered pair. Okay, that is a mouth full.
Master cylinder without booster. Single bore master cylinders: These unboosted hydraulic Master Cylinders are actuated by foot effort, via the brake pedal. The brake pressure is related to actuation force and depends on the piston bore size: the smaller the bore, the higher the pressure.
When replacing a brake master cylinder, we may need to adjust the push rod from the brake booster. This is easiest with the tool made for the purpose. Failure to properly adjust the push rod can result in a low pedal or brake lockup.