drilling performance is fit for specification of API Spec 4F,7K,8A, ... driving with independent AC Variable Frequency, and assembled with VFD system; the oil derrick adopts K type structure, the base ... adopts disc breaking or belt braking devices, the auxiliary breaking system adopts electromagnetic eddy current device etc, for hoister, drum, ... 16)7.5(25)7.5(25) 9(30)drilling performance oil drilling ...