* **Outer shell (oil reservoir):** Contains hydraulic oil.
* **Hydraulic pump:** Includes a handle, small piston (pump core), pump body, suction valve, and discharge valve; responsible for generating pressurized oil.
* **Cylinder:** Contains the large piston and is the core component that generates lifting force.
* **Piston rod (cap):** The part that directly contacts and lifts the load.
* **Return valve (drain valve):** A switch that controls the jack's descent; typically, clockwise rotation closes and counter-clockwise rotation opens.
* **Safety valve:** Automatically opens when the system pressure exceeds the rated value, preventing overload damage to the jack and providing safety protection.
