# Crane & Pulley

> Lifting more than you weigh

- Date: c. 515 BCE
- Era: Antiquity
- Domain: [Mechanics](https://lastcodex.org/en/domains/mechanics/)
- Rebuild stage: III (Crafts & cities)
- Difficulty: 3/5
- URL: https://lastcodex.org/en/inventions/crane/

A crane lifts a load by trading distance for force: a rope runs through several pulleys and onto a drum turned by a winch or a treadwheel, so that a few people can raise a stone many times their own weight. Greek builders used cranes from the late sixth century BCE, and Roman and medieval builders used them to raise temples and cathedrals and to load ships.

![Crane & Pulley · Lifting more than you weigh](https://lastcodex.org/_astro/plate.Vzaw-exp_n0hwh.webp)

## Legend

1. Leg of the timber frame
2. Stay rope
3. Treadwheel
4. Winding drum
5. Upper block with two pulleys
6. Lower block with one pulley
7. Lewis set in the stone

## What it is

A crane is a frame that holds a load in the air while people or engines raise it. The ancient crane had three parts: a timber frame or mast held by stay ropes, a set of pulleys at its head, and a winch at its foot. The winch was a horizontal axle turned with levers, or a large wheel that men walked inside, the treadwheel.

Each of its parts, the lever, the wheel and the rope, is older than the crane. The crane combines them so that the small force of a few people, applied over a long distance, becomes a large force over a short one.

## How it works

![A pulley fixed to a beam and a movable pulley below it carrying a stone, with one rope tied to the beam and passing under the lower wheel and over the upper one](https://lastcodex.org/_astro/v3.CLd4BZdz_Z27yP9i.webp)
_The simplest tackle: two strands hold the lower pulley, so the pull needed is about half the weight._

A single fixed pulley only changes the direction of a pull. The gain comes when the load hangs from a movable pulley. The rope then holds it on two strands, and each strand carries half the weight. To lift the stone by one metre you must pull two metres of rope, but with half the effort.

Add more pulleys to both blocks and the load is shared by more strands. Vitruvius, writing in the late first century BCE, names the blocks by their number of pulleys: three for the trispastos, five for the pentaspastos, and many for the polyspastos. With five strands, a pull equal to the weight of 20 kg holds about 100 kg, before friction. Friction in the axles of the pulleys takes back part of the gain, more with every pulley added.

The winch multiplies the force a second time. A rope wound on a thin axle and turned by long levers acts like a wheel and axle: if the levers are ten times longer than the axle's radius, the force on the rope is ten times the force on the levers. A treadwheel works the same way, with the weight of the men walking inside it as the effort. For very heavy loads, Vitruvius describes a drum wide enough for men to walk inside it, which gives more power than a capstan.

![Iron lifting tongs like large scissors, their tips set into two notches cut in the upper edges of the sides of a squared stone block, tied by ropes to a single ring](https://lastcodex.org/_astro/v1.B3I3ow_M_ZVx0iN.webp)
_Greek lifting tongs: pulling on the ring squeezes the tips into notches cut in the block._

The load also has to be held. Greek builders cut holes or U-shaped channels in their blocks for ropes, used iron tongs whose tips fitted into holes in the sides, or set a lewis, a dovetailed iron wedge, into a hole in the top. These cuttings, still visible on temple stones, are the main evidence for the use of cranes. Vitruvius describes iron shears hung under the lower block, their teeth fitted into holes in the stone. Building cranes of this kind had little reach to the side, so a block was lowered close to its final place and pushed into position with levers.

## How to build it

A tabletop model shows how pulleys and a winch multiply force. Keep it small: it is a demonstration, not a lifting device.

**Make the frame.** Lash two wooden dowels or broom handles about 1 m long together near their tops, spread their feet about 50 cm apart on a baseboard and screw them down. Clamp the baseboard to a sturdy table so the model cannot tip, and tie two stay cords from the top to screw eyes at the back of the board, so that the frame leans slightly forward but the hanging load stays above the board.

**Rig the tackle.** Hang a small pulley block with two sheaves from the top and a block with one sheave below it. Tie a strong cord to the top of the lower block, take it over one upper sheave, under the lower sheave and over the second upper sheave. Three strands now hold the lower block.

**Add a winch.** Drill a hole through each leg near the bottom and pass a short dowel through both so that it turns freely; glue a crank handle to one end; the free end of the cord will be tied to its middle after the first test below. Drill a hole in one leg for a removable peg: with the peg in, the crank rests against it and holds the load. Keep hold of the crank whenever you pull the peg out to wind further.

**Measure the gain.** Make this first test before the cord is tied to the axle. Weigh the lower block, then hang a bag of sand of no more than 500 g from it. Pull the free end slowly and steadily with a spring balance, lifting the bag only a few tens of centimetres: you should read a little more than a third of the bag and block together; the rest is friction. Lower the bag, tie the cord to the middle of the axle and compare how far the crank handle travels with how far the bag rises.

> **Safety.** Keep a hand on the crank whenever the load is raised: a plain axle runs back as soon as it is let go. Set the model where a falling bag cannot land on hands or feet, and keep fingers clear of the pulleys and the winding axle. Do not scale the model up to lift heavy objects: real lifting needs equipment rated and approved for lifting and lowering suspended loads, used by people trained in rigging.

## History and evolution

The pulley appears on an Assyrian relief of the ninth century BCE. Greek builders of the seventh century BCE cut rope channels in blocks of 200 to 400 kg at Isthmia and Corinth, and some researchers think lifting frames were being tried by then. Cranes became normal on Greek building sites from about 515 BCE, when cuttings for lifting tongs and lewis irons appear on temples such as that of Apollo at Delphi. The first clear written description of the compound pulley is in the Mechanical Problems, a Greek text of the early third century BCE.

Roman builders used both the winch and the treadwheel. A relief from the tomb of the Haterii family in Rome, carved around 100 CE, shows a treadwheel crane at work. Modern estimates, which assume a tackle of three rows of five pulleys, suggest that the largest compound crane, the polyspastos, could lift about 3 tonnes with four men at the winch, and about 6 tonnes with a treadwheel. The heaviest Roman blocks, such as the architraves of Baalbek, needed several cranes or other means.

![A large wooden treadwheel in a cathedral roof space, with a rope from its drum hanging through an opening in the floor to a stone block](https://lastcodex.org/_astro/v2.DNHygsNx_rMCnc.webp)
_A medieval treadwheel hoist set above the vaults: the rope from the drum drops through an opening in the floor._

Treadwheel cranes return in French building records around 1225, and harbour cranes are documented at Utrecht in 1244, Antwerp in 1263 and Bruges in 1288. Gothic builders often worked their hoists from the roof timbers, above the vaults they were building, and several medieval treadwheels still stand in English church towers. The great harbour crane of Gdańsk, built in 1442–1444, burned in 1945, and its timberwork has been rebuilt. In 1586 Domenico Fontana raised the Vatican obelisk, estimated at 330 to 360 tonnes, with a timber lifting tower. From 1801 two steam engines worked the cranes that built the London Dock, and in the 1840s William Armstrong built water-powered hydraulic cranes; electric motors and steel jibs came later, but cranes still lift with pulley blocks and a drum.

## Key figures

- Earliest firm evidence: Lifting cuttings on Greek temple blocks, c. 515 BCE
- Roman polyspastos (modern estimate): About 3 t with four men at a winch, about 6 t with a treadwheel
- Gdańsk harbour crane: Built 1442–1444, timberwork rebuilt after 1945
- Vatican obelisk, 1586: About 330 to 360 t (estimates vary), raised by Domenico Fontana

## Requires

- [Rope & Cordage](https://lastcodex.org/en/inventions/rope/): Twisted fibres that hold the world (50,000 years ago)
- [Wheel & Axle](https://lastcodex.org/en/inventions/wheel/): Rolling instead of dragging (c. 3,500 BCE)

## Sources

- [J. J. Coulton, Lifting in early Greek architecture (Journal of Hellenic Studies 94, 1974)](https://eclass-b.uoa.gr/modules/document/file.php/BAAG112/630416_Lifting%20in%20Early%20Greek%20Architecture_Coulton_Journal%20of%20Hellenic%20Studies1974.pdf), Society for the Promotion of Hellenic Studies (copy hosted by the University of Athens)
- [Vitruvius, The Ten Books on Architecture, Book X (hoisting machines)](https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius/10*.html), LacusCurtius, University of Chicago
- [Greek temple ruins suggest lifting machines in use 1.5 centuries earlier than previously believed](https://www.newswise.com/articles/greek-temple-ruins-suggest-lifting-machines-in-use-1-5-centuries-earlier-than-previously-believed), University of Notre Dame, via Newswise
- [Rochester Bridge Trust magazine: John Rennie and the London Dock (steam engines working the construction cranes, 1801)](https://rbt.org.uk/wp-content/uploads/2021/11/RBT-40pp-A4-Magazine-Single-Pages-Updated.pdf), Rochester Bridge Trust
- [Crane (machine)](https://en.wikipedia.org/wiki/Crane_(machine)), Wikipedia
- [Treadwheel crane](https://en.wikipedia.org/wiki/Treadwheel_crane), Wikipedia
- [Treadwheel crane, Harwich (built 1667): wheels of 16 ft on an axle of 13½ in](https://www.harwich-society.co.uk/maritime-heritage-trail/treadwheel-crane/), The Harwich Society
- [Block and tackle (friction: the sheave friction factor of API RP 9B)](https://en.wikipedia.org/wiki/Block_and_tackle), Wikipedia
- [Human power (sustained output of a labourer, after Marks' Standard Handbook for Mechanical Engineers)](https://en.wikipedia.org/wiki/Human_power), Wikipedia

Fact-checked on 2026-10-12.

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