A traveling block is the freely moving section of a

block and tackle A block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads. The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one ...

that contains a set of pulleys or

sheave A sheave () or pulley wheel is a grooved wheel often used for holding a belt, wire rope, or rope and incorporated into a pulley. The sheave spins on an axle or bearing inside the frame of the pulley. This allows the wire or rope to move fre ...

s through which the drill line (wire rope) is threaded o
reeved
and is opposite (and under) the

crown block A crown block is the stationary section of a block and tackle that contains a set of pulleys or sheaves through which the drill line (wire rope) is threaded oreevedand is opposite and above the traveling block. The combination of the traveling b ...

(the stationary section). The combination of the traveling block,

and wire rope drill line gives the ability to lift weights in the hundreds of thousands of pounds. On larger

drilling rig A drilling rig is an integrated system that drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to drill wat ...

s, when raising and lowering the derrick, line tensions over a million pounds are not unusual.

See also