Xem Studiomeasured geometryLibrary › Mechanisms › Pulleys and tackle ·
Blocks and tackle, two sheaves in each block (4 : 1)
How much does a block and tackle reduce the effort? · Hardware · basis: Xem Studio design following Brown No. 14 (1868)
Also called: block and tackle, tackle, fiddle block, 4 to 1 pulley, polipasto (aparejo), Flaschenzug
Exact dimensions. True size, with no printing tolerance added.
- sizes
- 4 in table
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.
Blocks and tackle, two sheaves in each block size chart
| 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
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Henry T. Brown (1868, public domain) | Five Hundred and Seven Mechanical Movements — scan on archive.org | web | Publisher's page; dimensions are facts |
| 507movements.com | Brown's movement No. 14: figure, his text and an animation | web | Publisher's page; dimensions are facts |
Free files
★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json
| blocks-and-tackle-mechanism-assembly | Assembled mechanism, all parts placed at one pose (STEP keeps each part separate) | STEP · STL |
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=blocks-and-tackle-mechanism
Fits with
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.