This document discusses hydraulic workover units (HWO units) used for well maintenance. It provides information on: - What an HWO unit is and its history of development since 1929 - The uses of HWO units, which include pulling/running completions, fishing, cementing, and more - The types of HWO units - short stroke and long stroke - Specifications for short stroke and long stroke units including maximum lift/snubbing forces, stroke length, and torque ratings - Benefits of using HWO units such as versatility of use onshore/offshore, ease of transportation, ability to pull and push, and reduced costs - Components of an HWO unit including j