Sub-structure is divided into two types such as fast assembly type and lifting type.
Fast assembly type structure is applicable to mechanical drilling rigs, wherein front sub-structure is higher so as to install the standard BOP. However, the rear sub-structure is lower so as to install heavy main draw-works and transmission parts.
The lifting structure is applicable to power-driven drilling rigs. And drilling machine and the equipments on the floor are installed at low position. The derrick will be lifted up as the floor is at low position, then the derrick and the floor will be up completely. The derrick floor is equipped with two hydraulic pressure cylinders at left and right side, which are used for bumper when the floor lifts up and top push force when releasing.
Lifting structures can be further divided into double-lifting, continuous lifting, synchronous lifting and vertical & continuous lifting, you can configure it as required