Draw-works are a piece of hoisting equipment that is used to raise and lower the drilling line on a rotary drilling rig. The drilling line, a large diameter mechanical cable, supports the drill string as well as ancillary equipment that is fed in and out of the wellbore. Draw-works are comprised of a drum, motor or powertrain, gearbox, and braking system. The drilling line exiting the draw-works is fed through a block and tackle system, crown block and traveling block, to give a mechanical advantage over control of the drilling line.
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Draw-works may incorporate regenerative braking systems that harness the braking power on descent for other rig processes. The motor or power train is used to reel in the drilling line on ascent. Draw-works may also provide auxiliary power to operate supporting equipment such as rotary tables or catheads, (winches.)