... are driving together; the drum is driving with independent AC Variable Frequency, and assembled with VFD system; the oil derrick adopts K type ... adopts disc breaking or belt braking devices, the auxiliary breaking system adopts electromagnetic eddy current device etc, for hoister, drum, drill ... )2250(500,000)3150(700,000)4500(1000,000) Lifting System Rope Tied System4×55×66×7 Diameter of the Lifting ...