# Blocks and tackle, two sheaves in each block (4 : 1)

> How much does a block and tackle reduce the effort?

- Category: Mechanisms › Pulleys and tackle
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 14 (1868)
- Page: https://xemstudio.com/objects/blocks-and-tackle-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=blocks-and-tackle-mechanism · Plain text: https://xemstudio.com/objects/blocks-and-tackle-mechanism/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- With n sheaves in the lower (moving) block, 2n strands hold it up: the power is the weight divided by twice the number of lower sheaves (P = W/4 here), and the hauling part moves four times as far.
- Drawn as a fiddle tackle so every strand hangs vertical in one plane: the upper block has pitch-Ø80 and pitch-Ø30 sheaves one above the other, the lower block pitch-Ø19 and pitch-Ø25 side by side. Standing end on the upper block's becket; strands at x = −34, −15, 15, 40 carry the load, the hauling part comes down at x = −40.
- Brown's No. 14 (blocks and tackle). Real blocks put the sheaves side by side on one pin; the rope then leads slightly sideways between them.
- Parts (each has its own page): tackle-beam-240-sockets, tackle-block-fiddle-upper-80-30, tackle-block-fiddle-lower-19-25, rope-sheave-3mm-pitch-80, rope-sheave-3mm-pitch-30, rope-sheave-3mm-pitch-19, rope-sheave-3mm-pitch-25, ropes-3mm-blocks-and-tackle, tackle-weight-d40x40-socket, dowel-pins-metric.
- Brown's movement No. 14 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| upper block | pitch Ø80 + pitch Ø30 sheaves |
| lower block | pitch Ø19 + pitch Ø25 sheaves |
| supporting strands | 4 |
| mechanical advantage | 4 (no friction) |

## Where the files are

- Henry T. Brown (1868, public domain): [Five Hundred and Seven Mechanical Movements — scan on archive.org](https://archive.org/details/fivehundredseven00browiala) — web — Publisher's page; dimensions are facts
- 507movements.com: [Brown's movement No. 14: figure, his text and an animation](https://507movements.com/mm_014.html) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/blocks-and-tackle-mechanism/index.json · license: https://xemstudio.com/files/hardware/blocks-and-tackle-mechanism/LICENSE.md

- blocks-and-tackle-mechanism-assembly: [STEP](https://xemstudio.com/files/hardware/blocks-and-tackle-mechanism/blocks-and-tackle-mechanism-assembly.step) · [STL](https://xemstudio.com/files/hardware/blocks-and-tackle-mechanism/blocks-and-tackle-mechanism-assembly.stl) — Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)

## Questions

**How much does a block and tackle reduce the effort?**

With n sheaves in the lower (moving) block, 2n strands hold it up: the power is the weight divided by twice the number of lower sheaves (P = W/4 here), and the hauling part moves four times as far.

## Fits with

- [Tackle beam 240 × 20 × 12 with Ø3 sockets every 5 mm](https://xemstudio.com/objects/tackle-beam-240-sockets/)
- [Upper fiddle block: pitch-Ø80 and pitch-Ø30 sheaves one above the other, with becket](https://xemstudio.com/objects/tackle-block-fiddle-upper-80-30/)
- [Lower fiddle block: pitch-Ø19 and pitch-Ø25 sheaves side by side](https://xemstudio.com/objects/tackle-block-fiddle-lower-19-25/)
- [Rope sheave for Ø3 rope, pitch Ø80 (rope centre), Ø84.4 rim, Ø4 bore](https://xemstudio.com/objects/rope-sheave-3mm-pitch-80/)
- [Rope sheave for Ø3 rope, pitch Ø30 (rope centre), Ø34.4 rim, Ø4 bore](https://xemstudio.com/objects/rope-sheave-3mm-pitch-30/)
- [Rope sheave for Ø3 rope, pitch Ø19 (rope centre), Ø23.4 rim, Ø4 bore](https://xemstudio.com/objects/rope-sheave-3mm-pitch-19/)
- [Rope sheave for Ø3 rope, pitch Ø25 (rope centre), Ø29.4 rim, Ø4 bore](https://xemstudio.com/objects/rope-sheave-3mm-pitch-25/)
- [Ø3 rope for the blocks and tackle, two sheaves in each block (drawn in place)](https://xemstudio.com/objects/ropes-3mm-blocks-and-tackle/)
- [Weight Ø40 × 40 with a Ø3 top socket (394.58 g in steel)](https://xemstudio.com/objects/tackle-weight-d40x40-socket/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)