1.Zj40/2250db ac drilling rig is suitable for the exploration of petroleum and gas wells with a depth of 2000-3200m by 127mm drilling rod, or a depth of 2500-4000m by 114mm drilling rod. 2.Ac-dc-ac drive system. 3. Single shaft drawwork, drum notch. Hydraulic disc type brake is adopted as the main, while energy-losing brake or etn brake is adopted as the auxiliary. 4.The rotary table adopts independent drive. 5.Parallelogram seat realizes the low-level installation of table-board equipments and derrick, then rises them up by right of drawwork. 6.The main mechanical components of drilling rig follow the standard of api with marks According to customer's request