Substructure--Main features:                                                      Specification (Clickhere)

(1)The substructure is classified into box on box type, block-combination type, slingshot type,      swing up type and telescoping type.
(2)The substructure of box on box type or block-combination type, has a relative higher clearance      at front platform, satisfies the installation requirement of standard BOP, if the substructure at      back platform is lower, it is required to use heavy equipments such as drawworks and      transmission unit etc.
(3)The substructure of slingshot type is used for electric rig, the drill floor and equipments on it      can be installed at low position , and then the drill floor and mast can be raised together. There      are hydraulic buffer cylinders on the left and right of the drill floor, while mast rising, they act as      bumper, while laying down, they act as a push force.
(4)The swing up structure, the drill floor and equipments on it can be installed at low position ,      and the mast can be raised at low location of drill floor, then the whole drill floor.
(5)The telescoping structure, mast and substructure are lifted with hydraulic cylinder ; the      structure strength is properly , small weight, easy for rig-up and transportation.
(6)Conforming to API Spec 4F, marked with API.