Xem Studiomeasured geometry

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Two single blocks rove to advantage (3 : 1)

Why does it matter which block the hauling part leaves? · Hardware · basis: Xem Studio design following Brown No. 22 (1868)

Also called: rove to advantage, gun tackle, luff tackle, 3 to 1 pulley, aparejo a favor (3:1), Talje mit Vorteil geschoren (3:1)

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

sizes
4 in table

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.

Two single blocks rove to advantage size chart

parametervalue
upper blockpitch Ø40
lower blockpitch Ø20 + arm
strands on the load3
mechanical advantage3 (2 if rove to disadvantage)

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.orgwebPublisher's page; dimensions are facts
507movements.comBrown's movement No. 22: figure, his text and an animationwebPublisher'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

tackle-rove-to-advantage-mechanism-assemblyAssembled mechanism, all parts placed at one pose (STEP keeps each part separate)STEP · STL
Let your AI pull this. Add 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.
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Plain text: sheet.txt · JSON: /api/geometry?object=tackle-rove-to-advantage-mechanism

Two single blocks rove to advantage (3 : 1), isometric render of a generated part
Render of tackle-rove-to-advantage-mechanism-assembly from the free STEP; not to scale.

Fits with

Tackle beam 240 × 20 × 12 with Ø3 sockets every 5 mm, isometric render of a generated part
Tackle beam 240 × 20 × 12 with Ø3 sockets every 5 mm240.0×20.0×12.0 mm★ 1 file
Single block for a pitch-Ø40 sheave, stem up (fixed block), isometric render of a generated part
Single block for a pitch-Ø40 sheave, stem up (fixed block)50.4×13.0×68.2 mm★ 1 file
Lower block for a pitch-Ø20 sheave with a standing-end arm (tackle rove to advantage), isometric render of a generated part
Lower block for a pitch-Ø20 sheave with a standing-end arm (tackle rove to advantage)68.7×13.0×43.2 mm★ 1 file
Rope sheave for Ø3 rope, pitch Ø40 (rope centre), Ø44.4 rim, Ø4 bore, isometric render of a generated part
Rope sheave for Ø3 rope, pitch Ø40 (rope centre), Ø44.4 rim, Ø4 bore44.4×8.0×44.4 mm★ 1 file
Rope sheave for Ø3 rope, pitch Ø20 (rope centre), Ø24.4 rim, Ø4 bore, isometric render of a generated part
Rope sheave for Ø3 rope, pitch Ø20 (rope centre), Ø24.4 rim, Ø4 bore24.4×8.0×24.4 mm★ 1 file
Ø3 rope for the two single blocks rove to advantage (drawn in place), isometric render of a generated part
Ø3 rope for the two single blocks rove to advantage (drawn in place)63.0×3.0×128.0 mm★ 1 file
Weight Ø40 × 40 with a Ø3 top socket (394.58 g in steel), isometric render of a generated part
Weight Ø40 × 40 with a Ø3 top socket (394.58 g in steel)40.0×40.0×40.0 mm★ 1 file
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325), isometric render of a generated part
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)5 sizes★ 23 files

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.