API 7 K 20T Model - XJ350Z Workover Rig Components of On-shore Workover Rig 20T The small workover rig adopts heavy-duty classII chassis, with good mobility and wildness. The auxiliary equipment such as mast, winch, transmission box, driller's box and hydraulic winch are installed on the frame. Product Introduction 1. The small workover rig adopts heavy-duty classII chassis, with good mobility and wildness. The auxiliary equipment such as mast, winch, transmission box,