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AW28HS Series — 28mm Stepper Motor with Planetary Gearbox
The AW28HS series pairs Apexwell's NEMA 11 (28mm), 1.8° hybrid stepper motor with an M28GXR planetary gearbox, offering motor holding torque from 0.07 N·m to 0.13 N·m and rated output torque up to 2.5 N·m after reduction. With four available gear-train stages and reduction ratios from 3.7:1 to 720:1 on the same 28mm footprint, this series sits one step up from our NEMA 8 (AW20HS) stepper-planetary line, for applications needing more output torque and higher load capacity than a NEMA 8 gearmotor can deliver.
Shared Specifications (all models)
| Parameter | Value |
|---|---|
| Step Angle | 1.8° |
| Lead Wires | 4 (bipolar) |
| Gear Material | Metal (powder metallurgy) |
| Output Bearing | Ball bearings |
| Radial Play of Shaft | ≤0.05 mm |
| Thrust Play of Shaft | ≤0.3 mm |
| Max Radial Load | ≤3.5 kgf |
| Max Shaft Axial Load | ≤2.5 kgf |
| Backlash (no load) | ≤3° |
Motor Model Comparison
| Model | Body Length | Phase Current | Phase Resistance | Phase Inductance | Holding Torque | Rotor Inertia | Mass |
|---|---|---|---|---|---|---|---|
| AW28HS30-1004A | 30 mm | 1.0 A | 2.9 Ω | 1.9 mH | 0.07 N·m | 8.5 g·cm² | 0.09 kg |
| AW28HSA33-0804A | 33 mm | 0.8 A | 5.3 Ω | 3.3 mH | 0.08 N·m | 9.3 g·cm² | 0.10 kg |
| AW28HS40-0704A | 40 mm | 0.7 A | 6.5 Ω | 6.0 mH | 0.12 N·m | 13.5 g·cm² | 0.12 kg |
| AW28HSA45-0804A | 45 mm | 0.8 A | 7.8 Ω | 5.4 mH | 0.13 N·m | 15.0 g·cm² | 0.15 kg |
| AW28HSA48-0804A | 48 mm | 0.8 A | 8.6 Ω | 6.7 mH | 0.13 N·m | 17.2 g·cm² | 0.20 kg |
| AW28HS50-0674A | 50 mm | 0.67 A | 8.4 Ω | 5.6 mH | 0.12 N·m | 18.9 g·cm² | 0.21 kg |
M28GXR Planetary Gearbox Specifications
| Parameter | 1-Stage | 2-Stage | 3-Stage | 4-Stage |
|---|---|---|---|---|
| Reduction Ratio | 3.7, 5.2 | 14, 19, 27 | 51, 71, 100, 139 | 189, 264, 369, 516, 720 |
| Gearbox Length (L1) | 32 mm | 41 mm | 50 mm | 59 mm |
| Rated Output Torque | 0.3 N·m | 1.0 N·m | 2.0 N·m | 2.5 N·m |
| Transmission Efficiency | 80% | 70% | 60% | 50% |
| Weight | 93 g | 120 g | 150 g | 185 g |
Momentary torque moment is rated at three times the rated allowable load across all four stages. The same 12 reduction ratios (3.7 to 720:1) used on the AW20HS carry over to this frame size, now delivering up to 2.5 N·m of rated output torque instead of 0.5 N·m.
Typical Applications
With output torque up to 2.5 N·m and reduction ratios up to 720:1 on a 28mm footprint, the AW28HS series fits small robotic joints, camera gimbals and pan-tilt mechanisms, compact valve and damper actuators, lab automation stages, and other light-industrial positioning tasks where a NEMA 8 gearmotor runs out of torque or load capacity but a larger frame isn't needed.
Why Choose the AW28HS Gearmotor
Twelve reduction ratios across four gear-train stages let one motor selection be tuned across a wide speed/torque window without changing the mounting footprint. The ball-bearing output stage raises radial and axial load capacity well beyond what the bare motor shaft alone can support — up to 3.5 kgf radial and 2.5 kgf axial — while backlash stays within 3° at no load for repeatable positioning. Because the gearbox is factory-fitted and tested as a complete unit, output shaft alignment and gear mesh are verified before the motor ships. Custom shaft configurations and encoder feedback are available on request.
We can customize the electrical parameters of the motor and geometric dimensions such as the motor output shaft size according to customer requirements. Accessories including pulleys, eccentric gearboxes, planetary gearboxes and encoders can also be added. For more products and detailed specifications, please download the product catalog from the Download Center.
