The clutch master cylinder is connected to the clutch pedal and is the part of the hydraulic system that makes hydraulic pressure. The internal mechanism used to generate hydraulic pressure divides master cylinders into two primary categories: compensating port design and centre value design.

Compensating Port Design 

To produce piston movement in the master cylinder, the seal over port system employs a push rod attached to the clutch pedal. Seals attached to the piston move forwards when the piston moves. The primary seal travels over a small port in the cylinder wall, allowing fluid flow to and from the reservoir. The fixed portion of fluid contained between the master and slave cylinders is moved towards the slave cylinder once the primary seal passes over the port. This causes the clutch to disengage. A plunger type master cylinder is one type of seal over port. The piston moves through the seals rather than through the attached seals that move with the pistons.

Centre Value Design

Small hooks attached to the nose of the piston are used in the center-feed type system. When the clutch pedal is not depressed, these hooks engage a flange on the valve stem. A circular rubber seal on the opposite end of the valve stem keeps the master cylinder body at bay. This enables fluid flow into and out of the reservoir. When you depress the clutch pedal, the hooks release the valve stem, which falls to the bottom of the master cylinder body. The reservoir has now been separated from the fixed fluid, which is contained between the master and slave cylinders. As the clutch pedal is depressed further and the master cylinder piston moves further, fluid is forced towards the slave cylinder, resulting in clutch disengagement. Master cylinders are further classified into two types: integral reservoir systems and remote reservoir systems. An integral reservoir system’s fluid reservoir is built into the master cylinder body. A rubber hose connects the fluid reservoir of a remote reservoir system to the master cylinder body. The use of integral or remote reservoirs is determined by the amount of space available in the engine compartment. In seal over port and centre feed systems, both integral and remote reservoirs are used.