28P 28 mm Micro Planetary Gearbox¶
Product Overview¶
The SigGear 28P is a 28 mm micro planetary gearbox for compact motorized mechanisms that require higher torque capacity than smaller miniature planetary frames. Published configurations cover one to four stages, with reduction ratios from 3.83:1 to 759.7:1.
Product Identity¶
| Item | Description |
|---|---|
| Model | 28P |
| Product type | Micro planetary gearbox |
| Nominal outer diameter | 28 mm |
| Number of stages | 1 to 4 |
| Manufacturing process | Machining |
Key Specifications¶
| Parameter | Published value |
|---|---|
| Nominal outer diameter | 28 mm |
| 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° |
| Maximum permissible speed, continuous operation | ≤ 8,000 rpm |
| Adapted DC motor voltage | 3–36 VDC |
| Adapted DC motor power | below 30 W |
Torque values are preserved in the source unit, kgf·cm. Maximum momentary torque is not a continuous working rating.
Stage, Ratio and Performance Table¶
| Stages | Gearbox length L | Available reduction 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% |
Motor Compatibility¶
The adapted-motor sheet identifies DC motors with a nominal voltage of 3–36 VDC and power below 30 W. If the motor cannot meet the gearbox installation requirements, the motor and gearbox interface details need to be negotiated separately.
These are adapted-motor conditions, not an electrical voltage or power rating for the mechanical gearbox itself. Confirm the motor shaft, mounting interface, input speed, duty cycle and operating point for the selected gearbox ratio.
Dimensions and Interface¶
The published drawing shows a 28 mm body diameter, a 20 mm output shaft reference length and stage-dependent gearbox lengths of 25.6, 31.9, 38.2 and 44.5 mm. Use the approved drawing for shaft geometry, mounting holes, input-interface details and tolerance notation.
Typical Applications¶
- Compact robotic joints and grippers
- Medical and laboratory automation mechanisms
- Precision instruments and optical adjustment mechanisms
- Mini pumps and valve drives
- Smart hardware and compact actuators
Application suitability depends on the selected ratio, motor, load direction, duty cycle, installation and required service life.
Supply Configuration¶
SigGear can supply the planetary gearbox as a gearbox-only unit, or evaluate and match a motor based on the customer's specific application requirements to provide a complete motor + gearbox assembly.
Selection Information Required¶
Please provide:
- Required reduction ratio or output speed
- Continuous and momentary output torque
- Motor type, voltage, power, speed and shaft dimensions
- Available gearbox length and mounting interface
- Output-shaft requirements
- Radial and axial loads
- Duty cycle and ambient temperature
- Backlash, noise and service-life targets
- Prototype and annual quantity
Do not transfer the 28P specifications to another frame size or an unlisted stage configuration. Final selection and quotation require confirmation against the approved configuration drawing.
Engineering Resources¶
View 28P Technical Datasheet v1.0 View 28P Mechanical Interface v1.0 Download Simplified STEP - 4-Stage Reference
The Datasheet consolidates the currently published stage, ratio, torque, efficiency and motor-matching data. The Mechanical Interface summarizes the controlled 2D drawing.
A detailed full-assembly STEP is held as configuration-controlled engineering CAD and is supplied after model / stage / motor-interface review. The raw assembly is not published as a public download because it contains internal planetary transmission geometry.
Related Planetary Gearbox Resources¶
8–42 mm Planetary Gearbox Series Browse All Planetary Gearboxes Request CAD, Sample and Quote
Contact SigGear¶
Wanrong Wang
International Sales, SigGear