Parts of a Drilling Rig – Mast, Drawworks, Kelly, Mud Pump

All 26 parts on the diagram

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The whole rig 11

Mast The tower of the rig. It holds up the crown block and the string of drill pipe. Also called the derrick.
Crown block The fixed set of pulleys at the top of the mast. The drilling line runs over them.
Traveling block The set of pulleys that moves up and down inside the mast.
Hook It hangs under the traveling block and carries the swivel.
Drilling line The wire rope from the drawworks. It runs over the crown block and down to the traveling block.
Drawworks A large winch that reels the drilling line in and out. That raises or lowers the drill pipe.
Monkeyboard The small platform high in the mast where the derrickman works.
Substructure The frame the mast and the drawworks stand on.
Doghouse Used as the driller's office. A small room at the side of the rig floor.
Catwalk A long platform beside the rig. Pipe is laid here before it is pulled up to the floor.
Pipe racks Supports that hold the lengths of pipe lying flat.

The floor and the mud 9

Swivel It hangs from the hook and lets the drill pipe turn freely. The mud enters the pipe through it.
Kelly A square or six-sided steel bar hung from the swivel. The rotary table turns it, and it turns the drill pipe.
Rotary table The turning section of the rig floor. It turns the kelly and everything below it.
Standpipe A rigid pipe up the side of the mast. It carries mud from the pump up to the rotary hose.
Rotary hose A flexible hose from the top of the standpipe to the swivel. Also called the kelly hose.
Mud pump A large pump that circulates the drilling mud.
Mud pits Open tanks that hold the drilling mud. From here it is pumped back down the well.
Shale shaker Vibrating screens that take the rock cuttings out of the mud.
Mud return line The mud flows along it back to the shale shaker. The pipe runs from the top of the well. Also called the flowline.

Down the hole 6

Blowout preventer One or more large valves at the top of the well. They can be closed to hold the pressure in.
Cellar A pit under the rig floor. It makes room for the blowout preventers.
Conductor pipe The widest and topmost casing, put into the well first.
Drill pipe Steel pipe in joints screwed together. It turns the bit and carries the mud down.
Drill collars Heavy thick-walled pipe just above the bit. It puts weight on the bit.
Bit The tool at the bottom that cuts the rock.

How this list was compiled: Every name checked on 2026-09-30 in two independent glossaries. (1) US Occupational Safety and Health Administration, Oil and Gas Well Drilling and Servicing eTool, Illustrated Glossary, https://www.osha.gov/etools/oil-and-gas/illustrated-glossary and its text version https://www.osha.gov/etools/oil-and-gas/illustrated-glossary-text : all 26 names. (2) SLB Energy Glossary, https://glossary.slb.com/en/ , the entries mast, derrick, crown block, traveling block, hook, drawworks, monkeyboard, doghouse, catwalk, pipe rack, swivel, kelly, rotary table, standpipe, rotary hose, mud pit, shale shaker, mud return line, blowout preventer, cellar, conductor pipe, drillpipe, drill collar, drill bit and rig: every name again; drilling line is in its drawworks entry, mud pumps in its rig entry and substructure in its doghouse entry. Each detail line is written in our own words from what the two glossaries say. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's drawing, nothing traced. Licence: own work

How it works

A land rotary drilling rig, the kind that drills oil and gas wells, in three drawings. The first is the whole rig from the side, the second follows the drilling mud round, and the third goes down the hole to the bit.

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Hoisting and turning

The mast holds the crown block at its top. The drilling line runs from the drawworks over the crown block to the traveling block, which carries the hook and the swivel. The kelly hangs from the swivel through the rotary table. The table turns the kelly, and the kelly turns the drill pipe, the drill collars and the bit.

The mud, and the top of the well

The mud pump sends drilling mud up the standpipe and through the rotary hose into the swivel. The mud comes back along the mud return line to the shale shaker and the mud pits. The blowout preventer sits at the top of the well, in the cellar under the rig floor.

A rig with a top drive turns the drill pipe from above and needs no kelly or rotary table.

Questions and answers

What are the main parts of a drilling rig?

For hoisting: the mast, crown block, traveling block, drilling line and drawworks. For turning: the swivel, kelly, rotary table, drill pipe, drill collars and bit. For the mud: the pump, standpipe, rotary hose, shale shaker and mud pits. For well control: the blowout preventer.

What is the tower on a drilling rig called?

The mast or the derrick. A mast is a derrick that can be raised into place as one unit. Either way it holds the crown block at the top.

What does the drawworks do on a drilling rig?

It is the rig's hoist: a large winch that reels the drilling line in and out, which raises and lowers the drill pipe and the bit.

Where does the drilling mud go?

The mud pump sends it up the standpipe, through the rotary hose and the swivel, and down inside the drill pipe to the bit. It comes back up the hole and along the mud return line to the shale shaker and the mud pits.