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Input shaft
The input (high-speed) shaft, coupled to the motor. It turns at full motor speed, about 1440 rpm, and carries the small stage-1 pinion.
More about this part
- Speed: 1440 rpm
- Material: Alloy steel, hardened
Free 3D model · STL · GLB · AR
Helical gear reducer 3D model
By Parth Parmar, mechanical design engineer · 51 pieces, 29 parts · Updated
A gear reducer (gearbox) slows a motor down and multiplies its torque. A small gear on the fast input shaft drives a bigger gear on a slower shaft; the speed drops by the ratio of their tooth counts and the torque rises by almost the same factor. Two or more stages in series give big reductions.
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Download the helical gear reducer 3D model
3D model · .glbColours and named parts · 5.5 MB
Mesh · .stlMillimetres, Z-up, for CAD and slicers · 3.9 MB
Every part · .zip29 separate STL files · 0.9 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 | Two-stage helical gearbox · 16 : 1 · 1440 → 90 rpm |
|---|---|
| Parts modeled | 51 named parts in 7 systems (29 different parts to download) |
| Model size | 628 × 353 × 503 mm (real scale) |
| Formats | GLB (glTF 2.0) 5.5 MB, STL 3.9 MB, USDZ for iPhone AR, ZIP of part STLs 0.9 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 helical gear reducer
| Input stage | 5 parts: Input shaft, stage-1 pinion, coupling hub and key: everything turning at motor speed. |
|---|---|
| Intermediate shaft | 3 parts: The shaft between the stages, with the big stage-1 gear and the small stage-2 pinion. |
| Output stage | 3 parts: Output gear, output shaft and key: slow speed, high torque. |
| Bearings & seals | 6 parts: Six tapered roller bearings, two oil seals and the bearing covers. |
| Housing & lubrication | 6 parts: Split cast-iron housing, cover, breather, sight glass, drain plug and the oil itself. |
| Motor & base | 3 parts: Motor, coupling hub and the common base frame. |
| Hardware | 3 parts: Cover, foot and motor bolts. |
All 29 parts of the helical gear reducer, one by one
Every part with a picture, what it does and its own STL file: input shaft, stage-1 pinion (18 teeth), input shaft key, coupling hub (gearbox side), coupling spider, intermediate shaft, stage-1 gear (72 teeth), stage-2 pinion (19 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 · 0.9 MB
Input stage 5
Input shaft, stage-1 pinion, coupling hub and key: everything turning at motor speed.
Stage-1 pinion (18 teeth)
The stage-1 pinion, the smallest and fastest gear in the box. Its 18 helical teeth drive the 72-tooth gear, a 4 : 1 reduction. Helical teeth slide into mesh gradually from one end of the face to the other, so the drive is quieter and carries more load than straight spur teeth.
More about this part
A pinion and its gear always have opposite helix hands: here the pinion is left hand and the gear right hand.
- Teeth: 18
- Module: mn 2 mm
- Helix: 15° left hand
- Pitch dia: Ø37.3 mm
Input shaft key
A parallel key. It locks a coupling or sprocket to the shaft so torque passes through the key, not through friction.
More about this part
- Standard: DIN 6885 / ISO 773 style
Coupling hub (gearbox side)
A flexible jaw coupling between motor and gearbox. Its elastomer spider soaks up small misalignment and torque shocks.
More about this part
- Type: Jaw coupling with spider
Coupling spider
A flexible jaw coupling between motor and gearbox. Its elastomer spider soaks up small misalignment and torque shocks.
More about this part
- Type: Jaw coupling with spider
Intermediate shaft 3
The shaft between the stages, with the big stage-1 gear and the small stage-2 pinion.
Intermediate shaft
The intermediate shaft, between the two stages. It turns at 360 rpm and carries the big stage-1 gear and the small stage-2 pinion.
More about this part
Both gears on this shaft have the same helix hand. One is driven and the other drives, so their axial thrusts push in opposite directions and partly cancel, which unloads the bearings.
- Speed: 360 rpm
Stage-1 gear (72 teeth)
The stage-1 gear, 72 teeth. Four times the pinion's tooth count means it turns four times slower and carries four times the torque (minus a little friction).
More about this part
- Teeth: 72
- Module: mn 2 mm
- Helix: 15° right hand
- Pitch dia: Ø149.1 mm
Stage-2 pinion (19 teeth)
The stage-2 pinion, 19 teeth on a bigger module (3 mm), because the torque here is already four times higher than at the input.
More about this part
- Teeth: 19
- Module: mn 3 mm
- Helix: 15° right hand
- Pitch dia: Ø59.0 mm
Output stage 3
Output gear, output shaft and key: slow speed, high torque.
Output shaft
The output (low-speed) shaft. It turns 16 times slower than the motor, about 90 rpm, with roughly 153 N·m of torque from a 1.5 kW motor.
More about this part
- Speed: 90 rpm
- Torque: ≈ 153 N·m
- Ratio: 16 : 1
Output gear (76 teeth)
The output gear, 76 teeth, the largest part in the box. Its lowest teeth dip into the oil, so every turn it carries oil up into the meshes and flings it onto the walls for the bearings.
More about this part
- Teeth: 76
- Module: mn 3 mm
- Helix: 15° left hand
- Pitch dia: Ø236.0 mm
Output shaft key
A parallel key. It locks a coupling or sprocket to the shaft so torque passes through the key, not through friction.
More about this part
- Standard: DIN 6885 / ISO 773 style
Bearings & seals 6
Six tapered roller bearings, two oil seals and the bearing covers.
Input shaft bearing ×2
A tapered roller bearing, shown as its outer ring and cage. Helical teeth push the shafts sideways along their axes as well as sideways across them, so the bearings must take axial thrust as well as radial load; tapered rollers do both.
More about this part
- Type: Tapered roller
- Load: Radial + axial
Intermediate shaft bearing ×2
A tapered roller bearing, shown as its outer ring and cage. Helical teeth push the shafts sideways along their axes as well as sideways across them, so the bearings must take axial thrust as well as radial load; tapered rollers do both.
More about this part
- Type: Tapered roller
- Load: Radial + axial
Output shaft bearing ×2
A tapered roller bearing, shown as its outer ring and cage. Helical teeth push the shafts sideways along their axes as well as sideways across them, so the bearings must take axial thrust as well as radial load; tapered rollers do both.
More about this part
- Type: Tapered roller
- Load: Radial + axial
Input shaft oil seal
A radial lip oil seal where a shaft leaves the housing. A spring-loaded rubber lip rides on the turning shaft and keeps the oil in and the dirt out.
More about this part
- Type: Radial shaft seal, NBR
Output shaft oil seal
A radial lip oil seal where a shaft leaves the housing. A spring-loaded rubber lip rides on the turning shaft and keeps the oil in and the dirt out.
More about this part
- Type: Radial shaft seal, NBR
Bearing cover ×4
A bearing cover (end cap). It closes the bearing bore on the side where no shaft comes out and holds the bearing outer ring in place.
Housing & lubrication 6
Split cast-iron housing, cover, breather, sight glass, drain plug and the oil itself.
Lower housing
The lower housing, the gearbox body. It holds the bearing bores in exact alignment, carries the gear forces to the feet, and forms the oil sump.
More about this part
The split line runs through the shaft centres, so the whole gear train can be lifted in or out from above.
- Material: Grey cast iron
Upper housing (cover)
The upper housing (cover), bolted to the lower half along the split line. Drawn see-through so the gears stay visible.
More about this part
- Material: Grey cast iron
Inspection cover
The inspection cover. Removing it lets a fitter look at the tooth contact pattern and the oil without opening the whole box.
Breather
The breather. As the gearbox warms up the air inside expands; the breather lets it out so pressure does not push oil past the seals. A blocked breather is a classic cause of leaking seals.
Lifting eye ×2
A lifting eye, cast into the cover for slinging the gearbox. It is rated for the gearbox alone, not with the motor attached.
Magnetic drain plug
The magnetic drain plug at the lowest point of the sump. Its magnet catches steel wear particles, which makes it a cheap first check on gear and bearing wear.
Motor & base 3
Motor, coupling hub and the common base frame.
Base frame
The common base frame. It keeps the motor and gearbox shafts lined up; misalignment here wears couplings, seals and bearings.
More about this part
- Material: Fabricated steel, painted
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. The gearbox turns its fast, low-torque output into slow, high-torque output.
More about this part
- Power: 1.5 kW
- Speed: 1440 rpm
Coupling hub (motor side)
A flexible jaw coupling between motor and gearbox. Its elastomer spider soaks up small misalignment and torque shocks.
More about this part
- Type: Jaw coupling with spider
Hardware 3
Cover, foot and motor bolts.
How does it work? Read the step-by-step guide, with key facts and common questions.
How a helical gear reducer works →Questions about this 3D model
Is the helical gear reducer 3D model free to download?
Yes. The helical gear reducer 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 helical gear reducer 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 29 parts as separate STL files.
How many parts does the helical gear reducer 3D model have?
51 named pieces in 7 systems (input stage, intermediate shaft, output stage, bearings & seals, housing & lubrication, motor & base, hardware). Repeated pieces such as bolts are folded together, which leaves 29 different parts, each one downloadable on its own.
Can I 3D print the helical gear reducer 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 helical gear reducer 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 helical gear reducer working in 3D?
Yes. Tap "Play live 3D here" or open the Engine-X atlas (engx3d.com/atlas#m=gearbox): 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: Helical gear reducer 3D model, Engine-X by Parth Parmar (engx3d.com)
Citation: Parmar, P. (2026). Helical gear reducer 3D model [3D model, CC BY-NC 4.0]. Engine-X. https://engx3d.com/3d-models/gear-reducer
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