What are the parts of a hydraulic cylinder?

A hydraulic cylinder is made up of 7 main components:

1. Cylinder Barrel (Main, Body). The barrel is the cylindrical body of the cylinder. The barrel guides the piston and provides a sealing surface for the piston seal. The barrel is also the structural part of the cylinder that holds the ends in place.
2. Cylinder Cap (Back End, Blind End, Blind Head, Rear End). A cylinder end closure which completely covers the bore area (opposite the rod end).
3. Cylinder Head (Packing Gland, Stuffing Box, Head End, Front End, Front Face, Rod End). The head gland or stuffing box is a cylinder component that serves more than one purpose. It retains the static and dynamic seals at the head end of the cylinder, it seals off at the end of the cylinders, it is the support or guide for the rod and it is the mechanical stop to keep the piston from falling out of the cylinder barrel.
4. Piston. The piston is a cylinder component that has multiple purposes. The piston retains the primary seal from the extend side of the cylinder and the retract side of the cylinder. It is the component that moves back and forth from the hydraulic oil. The piston is the mechanical means of connecting and moving the rod in and out of the cylinder as well as serves as a guide for one end of the piston rod.
5. Piston Rod. The rod is also known as the cylinder shaft, plunger or ram. It is the round device that moves in and out of the cylinder. The piston rod can be solid or hollow. The rod is usually plated, or heat treated to provide better wear and corrosion resistance.
6. Ports. Cylinder ports are the means in which the cylinder is able to have fluid lines or conduits connected. O-ring Boss (SAE) Port is a port that has straight or parallel threads as well as an O-ring to seal the threads. Pipe port threads are tapered threads that count on interference between the male and female threads to do the sealing. 4-Bolt Flange Port is a port that counts on 4 bolts to hold to two halves together. This type uses an O-ring to do the sealing. BSP is a British Standard Pipe Thread.
7. Seals.
   1. Static seals keep the joint pressure tight.
   2. Rod wiper / scraper is provided to remove and prevent foreign material from entering the bearing and seal area.
   3. Rod seals hold pressure in the cylinder by preventing fluid from leaking out.
   4. Piston seals prevent pressurized fluid from leaking across the piston as the system pressure pushes the piston and rod assembly down the cylinder bore.