In this type of gearbox, all the gears of the main shaft are in constant mesh with the corresponding gears of the countershaft. A sliding dog clutch is provided on the main shaft.
Gear ratios 0.75, 1.33 and neutral.
This model was designed in Tinkercad.
3-speed gearbox with reverse gear : Constant Mesh 3 Speed Gearbox with Reverse Gear by Bootjevaarder | Download free STL model | Printables.com

Printing and Assembly
The parts should be printed on a smooth build plate, not textured.
If possible, avoid elephant foot.

I printed the model on a PRUSA MINI, with PLA+ filament, layer height 0.15 mm.
I use Hard Plastic Glue where necessary.

For assembled and exploded views, use .stl files A0… X0… (do not print).
Printing and assembly in alphabetical order (A1 → X1).

Choise between Spur and Herringbone gears (A4 B2).

Dimensions: 95 x 63 x 101 mm.
Weight: 0.1 kg.

Join gearbox to “4 Stroke Flathead Engine” (= 135305)
Print parts X1 → X5.
4 Stroke Flathead Engine by Bootjevaarder | Download free STL model | PrusaPrinters

To couple the gearbox to the engine, the “Cranked Handle” of the engine must be removed.

The engine, coupling bracket and gearbox click into the “X1-Sled”.
Important: Part “X2-Coupling Bracket” must be assembled in the correct orientation (ARROW).

Operation
Use the cranked handle to rotate the gearbox / engine.
To couple / uncouple the gearbox from the engine, use “X5-Coupling Selector Fork”.
For shifting gears, use “A3-Selector Fork”.

Constant Mesh Two Speed Gearbox

by Bootjevaarder · original on Printables ↗

Learning / Engineering

♥ 397⬇ 1.1k🖨 16 prints

License: Creative Commons — Attribution — Noncommercial — NoDerivatives ↗

Print profiles

C4-Pointer on Main Shaft.stl
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X2-Coupling Bracket-ARROW.stl
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C5-Coupling Plate on Counter Axle.stl
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C2-Bearings.stl
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X4-Coupling Selector.stl
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X3-Slider On Engine Axle.stl
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C1-Housing.stl
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X1-Sled.stl
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B2-Counter Shaft SPUR Gears.stl
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A4-Main Shaft SPUR Gears.stl
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X0-Coupling Exploded View.stl
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A00-Gearbox Exploded View.stl
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A0-Gearbox Assembled.stlDEFAULT
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A000-Gears and Shafts-Exploded View.stl
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A3-Selector Fork.stl
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A1-Main Shaft.stl
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B1-Counter Shaft.stl
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C3-Cranked Handle.stl
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A2-Sliding Dog Clutch.stl
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D1-Click Stand.stl
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X5-Coupling Selector Fork.stl
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B2-Counter Shaft HERRINGBONE Gears.stl
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A4-Main Shaft HERRINGBONE Gears.stl
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