View in your room · AR
Input shaft
The input shaft is driven by the motor through a clamping coupling, and its end carries the sun gear.
More about this part
- Speed: 1440 rpm
- Torque: ≈ 9.9 N·m
Free 3D model · STL · GLB · AR
Planetary gearbox 3D model
By Parth Parmar, mechanical design engineer · 55 pieces, 27 parts · Updated
A planetary gearbox has a central sun gear, several planet gears around it on a carrier, and an outer ring gear with internal teeth. Hold the ring still and drive the sun: the planets roll round inside the ring and turn the carrier slowly. The ratio is 1 + ring teeth ÷ sun teeth.
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Live 3D: drag to turn it, pinch to zoom, explode it, cut it open, X‑ray it and watch it run. Free, in your browser, no app. Open it full screen →
Download the planetary gearbox 3D model
3D model · .glbColours and named parts · 3.5 MB
Mesh · .stlMillimetres, Z-up, for CAD and slicers · 2.4 MB
Every part · .zip27 separate STL files · 0.3 MB · or one by one below
Single parts: scroll to the parts list. These are learning models, not a print kit: some parts touch or overlap and there are no fit tolerances.
Free for personal and educational use under CC BY-NC 4.0. Credit “Engine-X by Parth Parmar (engx3d.com)” when you share or remix it. Don’t sell the files or prints. For commercial use, get in touch. Every file carries the Engine-X mark and a hidden digital fingerprint that identifies it.
Key facts
| Machine | Sun 18 · planets 3 × 27 · ring 72 · 5 : 1 |
|---|---|
| Parts modeled | 55 named parts in 6 systems (27 different parts to download) |
| Model size | 300 × 334 × 695 mm (real scale) |
| Formats | GLB (glTF 2.0) 3.5 MB, STL 2.4 MB, USDZ for iPhone AR, ZIP of part STLs 0.3 MB |
| Live 3D | Engine‑X atlas: true motion, explode, section, X‑ray |
| License | CC BY-NC 4.0, free with credit |
What’s inside the planetary gearbox
| Sun & input | 3 parts: Input shaft, sun gear and coupling hub, at motor speed. |
|---|---|
| Planet gears | 5 parts: Three planet gears with their needle bearings and thrust washers. |
| Carrier & output | 4 parts: Planet carrier, planet pins, output shaft and key: the slow, high-torque side. |
| Ring gear & housing | 10 parts: Fixed ring gear, housings, bearings, seal, oil and plugs. |
| Motor & base | 2 parts: Motor and base plate. |
| Hardware | 3 parts: Housing, foot and motor bolts. |
All 27 parts of the planetary gearbox, one by one
Every part with a picture, what it does and its own STL file: input shaft, sun gear (18 teeth), input coupling (clamping hub), planet gear 1 (27 teeth), planet needle bearing, planet thrust washer, planet gear 2 (27 teeth), planet gear 3 (27 teeth) and more. Open any part in the live 3D atlas to see where it sits and how it moves. A part used several times (valves, bolts) is shown once with its count.
↓ Download all parts · ZIP · 0.3 MB
Sun & input 3
Input shaft, sun gear and coupling hub, at motor speed.
Sun gear (18 teeth)
The sun gear, 18 teeth, in the middle of the set. It is cut on the end of the input shaft and turns at full motor speed, about 1440 rpm, driving all 3 planets at once.
More about this part
Because three planets share the work, each tooth mesh carries only about a third of the torque.
- Teeth: 18
- Module: 2.5 mm
- Pitch dia: Ø45.0 mm
Input coupling (clamping hub)
The input coupling (clamping hub) grips the motor shaft and turns the gearbox input shaft.
More about this part
- Type: Clamping hub
Planet gears 5
Three planet gears with their needle bearings and thrust washers.
Planet gear 1 (27 teeth)
A planet gear with 27 teeth that meshes with the sun and the ring at the same time. It meshes with the sun on its inside and with the ring gear on its outside, so it spins on its own pin and, at the same time, walks round the ring, carrying the carrier with it.
More about this part
Planets are idlers: they change nothing in the ratio by themselves. Their size just has to fit: ring teeth = sun teeth + 2 × planet teeth.
- Teeth: 27
- Module: 2.5 mm
- Pitch dia: Ø67.5 mm
Planet needle bearing ×3
A needle roller bearing inside a planet gear. It lets the planet spin on its pin; it is one of the hardest-working bearings in the box, because it carries the full tooth load of its planet.
More about this part
- Type: Needle roller
Planet thrust washer ×6
A thrust washer between a planet and the carrier plate. It keeps the planet centred on its pin and stops it rubbing on the carrier.
More about this part
- Material: Bronze
Planet gear 2 (27 teeth)
A planet gear with 27 teeth that meshes with the sun and the ring at the same time. It meshes with the sun on its inside and with the ring gear on its outside, so it spins on its own pin and, at the same time, walks round the ring, carrying the carrier with it.
More about this part
Planets are idlers: they change nothing in the ratio by themselves. Their size just has to fit: ring teeth = sun teeth + 2 × planet teeth.
- Teeth: 27
- Module: 2.5 mm
- Pitch dia: Ø67.5 mm
Planet gear 3 (27 teeth)
A planet gear with 27 teeth that meshes with the sun and the ring at the same time. It meshes with the sun on its inside and with the ring gear on its outside, so it spins on its own pin and, at the same time, walks round the ring, carrying the carrier with it.
More about this part
Planets are idlers: they change nothing in the ratio by themselves. Their size just has to fit: ring teeth = sun teeth + 2 × planet teeth.
- Teeth: 27
- Module: 2.5 mm
- Pitch dia: Ø67.5 mm
Carrier & output 4
Planet carrier, planet pins, output shaft and key: the slow, high-torque side.
Planet carrier
The planet carrier is the output member of the planetary gearbox, turning slowly as the planets roll round the ring. The three planet pins sit in it, so as the planets roll round the fixed ring, the carrier turns 5 times slower than the sun, in the same direction.
More about this part
Here the two three-armed plates are tied together by the planet pins; heavier carriers add bridges between the planets.
- Speed: 288 rpm
- Material: Ductile iron
Output shaft
The output shaft is part of the planet carrier and delivers the slow, high-torque drive. It turns at about 288 rpm with almost 5 times the motor torque, about 50 N·m before friction losses.
More about this part
- Speed: 288 rpm
- Torque: ≈ 50 N·m (ideal)
Output shaft key
The output shaft key, which locks the coupling or sprocket to the shaft.
More about this part
- Standard: DIN 6885 style
Planet pin ×3
A planet pin, pressed into both carrier plates, holds one planet gear at a fixed distance from the gearbox centre.
More about this part
- Material: Hardened steel
Ring gear & housing 10
Fixed ring gear, housings, bearings, seal, oil and plugs.
Ring gear (72 teeth)
The ring gear (annulus), 72 teeth cut on the inside. It is held still in the housing, which is what makes the carrier the slow output: ratio = 1 + 72 ÷ 18 = 5 : 1.
More about this part
Hold the carrier still instead and the ring becomes the output, turning backwards at 4 : 1; hold the sun and drive the ring, and the carrier turns at 1.25 : 1. One gear set, three ratios.
- Teeth: 72 (internal)
- Module: 2.5 mm
- Pitch dia: Ø180 mm
Gear housing
The gear housing around the ring gear, cast with the mounting feet. Drawn see-through so the gears stay visible.
More about this part
- Material: Grey cast iron
Input housing (motor adapter)
The input housing (motor adapter) bolts the motor to the gearbox. It keeps the motor shaft exactly in line with the sun.
More about this part
- Material: Cast aluminium
Output housing
The output housing holds the two output shaft bearings and the oil seal at the slow end of the gearbox.
More about this part
- Material: Grey cast iron
Input shaft bearing
The input shaft bearing, a deep-groove ball bearing in the input housing.
More about this part
- Type: Deep-groove ball
Output bearing ×2
An output shaft bearing is one of two ball bearings that support the planet carrier. Spaced apart, they carry the carrier and any side load from the driven machine (a sprocket or pulley on the shaft).
More about this part
- Type: Deep-groove ball
Output shaft oil seal
The output shaft oil seal: a spring-loaded rubber lip that keeps the oil in and the dirt out.
More about this part
- Type: Radial lip seal, NBR
Breather plug
The breather plug lets warm air out of the gearbox housing as it heats up, so the housing does not pressurise and push oil past the seal.
Oil level plug
The oil level plug marks the correct oil level: with the gearbox stopped, oil should just reach this hole.
Motor & base 2
Motor and base plate.
Motor (1.5 kW, 1440 rpm)
The driver: a 1.5 kW four-pole induction motor turning at about 1440 rpm on a 50 Hz supply.
More about this part
- Power: 1.5 kW
- Speed: 1440 rpm
Base plate
The base plate that holds the motor and gearbox in line.
More about this part
- Material: Fabricated steel, painted
Hardware 3
Housing, foot and motor bolts.
Foot bolt ×4
A hex bolt (grade 8.8) that holds the gearbox housings, motor or feet together.
More about this part
- Grade: 8.8
Motor bolt ×4
A hex bolt (grade 8.8) that holds the gearbox housings, motor or feet together.
More about this part
- Grade: 8.8
Housing bolt ×12
A hex bolt (grade 8.8) that holds the gearbox housings, motor or feet together.
More about this part
- Grade: 8.8
How does it work? Read the step-by-step guide, with key facts and common questions.
How a planetary gearbox works →Questions about this 3D model
Is the planetary gearbox 3D model free to download?
Yes. The planetary gearbox 3D model is free for personal and educational use under CC BY-NC 4.0: credit "Engine-X by Parth Parmar (engx3d.com)". Selling the files or prints, or other commercial use, needs written permission.
Which file formats is the planetary gearbox 3D model in?
GLB (glTF 2.0) with colours and named parts, STL in millimetres (Z-up) for CAD, slicers and 3D printing, USDZ for AR on iPhone, and a ZIP with all 27 parts as separate STL files.
How many parts does the planetary gearbox 3D model have?
55 named pieces in 6 systems (sun & input, planet gears, carrier & output, ring gear & housing, motor & base, hardware). Repeated pieces such as bolts are folded together, which leaves 27 different parts, each one downloadable on its own.
Can I 3D print the planetary gearbox model?
Yes, download the STL (whole machine or single parts) and open it in your slicer. It is a learning model at real scale, not a print kit: some parts touch or overlap and there are no fit tolerances, so scale it and print parts one by one.
How do I see the planetary gearbox in AR on my phone?
Tap "View in your room" on this page. Android opens Google Scene Viewer and iPhone opens AR Quick Look, both without an app, and you can place the model at real size on the floor or a table.
Can I see the planetary gearbox working in 3D?
Yes. Tap "Play live 3D here" or open the Engine-X atlas (engx3d.com/atlas#m=planetary): it runs in the browser with true motion, and you can explode it, cut it open and X-ray it.
How to credit or cite this model
Credit line: Planetary gearbox 3D model, Engine-X by Parth Parmar (engx3d.com)
Citation: Parmar, P. (2026). Planetary gearbox 3D model [3D model, CC BY-NC 4.0]. Engine-X. https://engx3d.com/3d-models/planetary-gearbox
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