Rotating And Traveling Equipment

Traveling block

A traveling block is the freely moving section of a block and tackle that contains a set of pulleys or sheaves through which the drill line (wire rope) is threaded or reeved and is opposite (and under) the crown block (the stationary section).
The combination of the traveling block, crown block and wire rope drill line gives the ability to lift weights in the hundreds of thousands of pounds. On larger drilling rigs, when raising and lowering the derrick, line tensions over a million pounds are not unusual.

crown block

The fixed set of pulleys (called sheaves) located at the top of the derrick or mast, over which the drilling line is threaded. The companion blocks to these pulleys are the traveling blocks. By using two sets of blocks in this fashion, great mechanical advantage is gained, enabling the use of relatively small drilling line (3/4 to 1 1/2 in. diameter steel cable) to hoist loads many times heavier than the cable could support as a single strand

block

A set of pulleys used to gain mechanical advantage in lifting or dragging heavy objects. There are two large blocks on a drilling rig, the crown block and the traveling block. Each has several sheaves that are rigged with steel drilling cable or line such that the traveling block may be raised (or lowered) by reeling in (or out) a spool of drilling line on the draw-works

Rotary Tables

The revolving or spinning section of the drillfloor that provides power to turn the drillstring in a clockwise direction (as viewed from above). The rotary motion and power are transmitted through the kelly bushing and the kelly to the drillstring. When the drillstring is rotating, the drilling crew commonly describes the operation as simply, "rotating to the right," "turning to the right," or, "rotating on bottom." Almost all rigs today have a rotary table, either as primary or backup system for rotating the drillstring. Topdrive technology, which allows continuous rotation of the drillstring, has replaced the rotary table in certain operations. A few rigs are being built today with topdrive systems only, and lack the traditional kelly system.

Sheave

A pulley. In oilfield usage, the term usually refers to either the pulleys permanently mounted on the top of the rig (the crown blocks), or the pulleys used for running wireline tools into the wellbore. In the case of the crown blocks, the drilling line, a heavy wire rope, is threaded between the crown blocks and the traveling blocks in a block and tackle arrangement to gain mechanical advantage. A relatively weak drilling line, with a breaking strength of perhaps 100,000 pounds [45,400 kg], may be used to lift much larger loads, perhaps in excess of one million pounds [454,000 kg]. During wireline operations, two sheaves are temporarily hung in the derrick, and the wireline is run from the logging truck through the sheaves and then down to the logging tool in the wellbore.

hook

The high-capacity J-shaped equipment used to hang various other equipment, particularly the swivel and kelly, the elevator bails or topdrive units. The hook is attached to the bottom of the traveling block and provides a way to pick up heavy loads with the traveling block. The hook is either locked (the normal condition) or free to rotate, so that it may be mated or decoupled with items positioned around the rig floor, not limited to a single direction.
swivel :A mechanical device that suspends the weight of the drillstring. It is designed to allow rotation of the drill string beneath it conveying high volumes of high-pressure drilling mud between the rig's circulation system and the drillstring