drilling performance is fit for specification of API Spec 4F,7K,8A, ... by energy consumption.2. Combination Rig: it takes the diesel engine as driving power source, and the driving chain box in ... adopts disc breaking or belt braking devices, the auxiliary breaking system adopts electromagnetic eddy current device etc, for hoister, drum, drill ... (16)7.5(25)7.5(25) 9(30)drilling performance oil drilling ...