28P 28 mm Planetary Gearbox - Technical Datasheet v1.0¶
Status: Public engineering evaluation reference
Release date: 2026-10-06
The SigGear 28P is a 28 mm planetary gearbox platform with one- to four-stage configurations. Performance values below are consolidated from the current canonical product page. Mechanical-interface details are linked to the controlled 2D drawing reference released for this model.
Key Specifications¶
| Parameter | Public value |
|---|---|
| Nominal outer diameter | 28 mm |
| Number of stages | 1-4 |
| Gearbox length range | 25.6–44.5 mm |
| Reduction ratio range | 3.83:1–759.7:1 |
| Rated allowable torque range | 20.0–50.0 kgf·cm |
| Maximum momentary torque range | 40.0–100.0 kgf·cm |
| Efficiency range | 66–90% |
| Backlash at no load | ≤ 1.2° |
| Continuous permissible input speed | ≤ 8,000 rpm |
Maximum momentary torque is not a continuous working rating.
The current public source does not state operating temperature for 28P; no value is inferred here.
Stage, Ratio and Performance¶
| Stages | Gearbox body length L | Available ratios | Rated allowable torque | Maximum momentary torque | Efficiency |
|---|---|---|---|---|---|
| 1 | 25.6 mm | 3.83 / 4.4 / 5.25 | 20.0 kgf·cm | 40.0 kgf·cm | 90% |
| 2 | 31.9 mm | 14.7 / 16.8 / 19.4 / 20.1 / 23 / 27.7 | 25.0 kgf·cm | 50.0 kgf·cm | 80% |
| 3 | 38.2 mm | 56.2 / 64.5 / 74.1 / 77 / 85.2 / 88.5 / 101.6 / 105.6 / 121.3 / 144.7 | 35.0 kgf·cm | 70.0 kgf·cm | 73% |
| 4 | 44.5 mm | 215.2 / 247.2 / 284 / 294.9 / 326.2 / 338.8 / 374.8 / 389.3 / 404.3 / 447.2 / 464.5 / 533.6 / 554.2 / 636.7 / 759.7 | 50.0 kgf·cm | 100.0 kgf·cm | 66% |
Load / Shaft Data Boundary¶
Radial load, axial load and shaft-play limits are not currently published for 28P in the canonical public specification. They are therefore not inferred from another frame size and must be confirmed for the selected configuration if required.
Motor Matching Reference¶
- Adapted DC motor nominal voltage: 3–36 VDC
- Adapted DC motor power: below 30 W
These are motor-matching conditions, not electrical ratings of the mechanical gearbox.
Mechanical Interface and CAD¶
View 28P Mechanical Interface v1.0
Download 28P Simplified STEP - 4-Stage Reference
A simplified public 4-stage STEP reference is released for early packaging and mechanical Design-In. The detailed full-assembly STEP remains configuration-controlled and request-only because it contains internal planetary transmission geometry.
For final CAD, provide the selected ratio, stage count and motor interface.
Request CAD / Controlled Drawing
Selection Information Required¶
Please provide:
- Required output speed or reduction ratio
- Continuous and momentary output torque
- Motor voltage, power and speed
- Motor shaft diameter and length
- Motor mounting-hole pattern and locating pilot
- Output-shaft requirements
- Radial and axial loads
- Duty cycle and ambient temperature
- Backlash, noise and service-life targets
- Prototype and annual quantity
Related Product¶
Engineering Contact¶
Wanrong Wang
International Sales / Sales Engineer, SigGear
wangwanrong@siggear.com