# Two single blocks rove to advantage (3 : 1)

> Why does it matter which block the hauling part leaves?

- Category: Mechanisms › Pulleys and tackle
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 22 (1868)
- Page: https://xemstudio.com/objects/tackle-rove-to-advantage-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=tackle-rove-to-advantage-mechanism · Plain text: https://xemstudio.com/objects/tackle-rove-to-advantage-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 one upper and one lower single block, the standing end can be made fast to the lower block and the hauling part led off it upward: then three strands act on the moving block and P = W/3. Rove the other way (hauling part off the fixed block) the same blocks give only 2 : 1.
- Pitch-Ø40 upper block, pitch-Ø20 lower block with an arm carrying the standing end 50 mm to the side; hauling part goes up at x = 40. The weight stem sits on the line of the three strands' resultant (x = 13.33).
- Brown's No. 22 (a pulley combination following the doubling rule).
- Parts (each has its own page): tackle-beam-240-sockets, tackle-block-20-top-stem, tackle-block-10-advantage, rope-sheave-3mm-pitch-40, rope-sheave-3mm-pitch-20, ropes-3mm-tackle-rove-to-advantage, tackle-weight-d40x40-socket, dowel-pins-metric.
- Brown's movement No. 22 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| upper block | pitch Ø40 |
| lower block | pitch Ø20 + arm |
| strands on the load | 3 |
| mechanical advantage | 3 (2 if rove to disadvantage) |

## 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. 22: figure, his text and an animation](https://507movements.com/mm_022.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/tackle-rove-to-advantage-mechanism/index.json · license: https://xemstudio.com/files/hardware/tackle-rove-to-advantage-mechanism/LICENSE.md

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

## Questions

**Why does it matter which block the hauling part leaves?**

With one upper and one lower single block, the standing end can be made fast to the lower block and the hauling part led off it upward: then three strands act on the moving block and P = W/3. Rove the other way (hauling part off the fixed block) the same blocks give only 2 : 1.

## Fits with

- [Tackle beam 240 × 20 × 12 with Ø3 sockets every 5 mm](https://xemstudio.com/objects/tackle-beam-240-sockets/)
- [Single block for a pitch-Ø40 sheave, stem up (fixed block)](https://xemstudio.com/objects/tackle-block-20-top-stem/)
- [Lower block for a pitch-Ø20 sheave with a standing-end arm (tackle rove to advantage)](https://xemstudio.com/objects/tackle-block-10-advantage/)
- [Rope sheave for Ø3 rope, pitch Ø40 (rope centre), Ø44.4 rim, Ø4 bore](https://xemstudio.com/objects/rope-sheave-3mm-pitch-40/)
- [Rope sheave for Ø3 rope, pitch Ø20 (rope centre), Ø24.4 rim, Ø4 bore](https://xemstudio.com/objects/rope-sheave-3mm-pitch-20/)
- [Ø3 rope for the two single blocks rove to advantage (drawn in place)](https://xemstudio.com/objects/ropes-3mm-tackle-rove-to-advantage/)
- [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/)