3 mm through bore
The Ø3 mm hollow shaft keeps the motor axis open for compact routing through the rotary centerline.
SP20HS 20 mm Hybrid Hollow Shaft Stepper Motor
Hybrid Hollow Shaft Stepper Motor
The SP20HS series is a compact 20 mm hybrid stepper motor with a 3 mm through hollow shaft, holding torque up to 0.02 N·m and optional EK1 encoder configurations for space-limited motion assemblies.
Positioning accuracy
High torsional rigidity and constant torsional backlash over the entire gearbox service life ensure consistently high performance
Compactness
High torque density thanks to high performance and short design
Low maintenance
Highest quality standards for a long service life and extended maintenance intervals
Technical data
Compact through-shaft motion
20 mm hybrid stepper motor with a 3 mm through bore
The SP20HS 20 mm hybrid hollow shaft stepper motor combines a compact square frame, holding torque up to 0.02 N·m and optional EK1 encoder configurations for space-limited rotary assemblies.
Two torque levels
Two verified motor lengths provide holding torque choices of 0.014 N·m and 0.02 N·m.
Optional EK1 feedback
EK1 encoder options support selectable resolutions with single-ended or differential output configurations.
Engineering information
Technical data
20 mmFrame size
0.014–0.02 N·mHolding torque
Ø3 mmThrough bore
27.2 / 38 mmMotor length
Motor
Electrical and mechanical parameters
| Model | Rated voltage | Current | Resistance | Inductance | Holding torque | Detent torque | Motor length |
|---|---|---|---|---|---|---|---|
| SP8HS2028 | 2.55 V | 0.5 Arms | 5.1 Ω | 1.5 mH | 0.014 N·m | 0.002 N·m | 27.2 mm |
| SP8HS2038 | 4.4 V | 0.5 Arms | 8.8 Ω | 2.7 mH | 0.02 N·m | 0.004 N·m | 38 mm |
Encoder option
EK1 resolution and output codes
| Resolution (PPR) | 100 | 108 | 120 | 125 | 128 | 200 | 250 | 256 | 300 | 360 | 400 | 500 | 1000 | 512 | 720 | 800 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Single-ended code | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| Differential code | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P |
Encoder option
Additional resolution selections
| Output code | 0 / A | 1 / B | 2 / C | 3 / D | 4 / E | 5 / F | 6 / G | 7 / H | 8 / I | 9 / J |
|---|---|---|---|---|---|---|---|---|---|---|
| Resolution | — | — | — | 1000 PPR | — | — | 2000 PPR | — | — | — |
Integration flexibility
Keep the rotation axis open in a compact 20 mm frame.
The hollow-shaft format supports through-axis routing while the two motor lengths provide a practical torque choice for compact precision equipment.
- Ø3 mm continuous hollow bore
- Four-lead bipolar motor connection
- Optional EK1 encoder configurations
Application fields
Compact rotary motion with a clear center axis
The SP20HS is intended for compact assemblies that need controlled rotary positioning and through-axis routing.
Optical positioning
Adjustment mechanisms with a light path or cable routed through the rotation axis.
Medical instruments
Compact rotary modules that need organized cable or media routing through the motor center.
Precision instruments
Space-limited positioning mechanisms with optional encoder feedback.
Compact robotics
Small joints and end-effectors that benefit from an open central routing channel.
System integration
Verified interfaces for mechanical and electrical design
Select the motor length, winding and encoder configuration according to the required torque, speed and feedback interface.
Motor variantsSP8HS2028 / SP8HS2038
Holding torque0.014 / 0.02 N·m
Shaft formatØ5 mm outer shaft with Ø3 mm through bore
Lead wires4 leads, AWG28, 320 ±20 mm
Encoder optionEK1, single-ended or differential output
Discuss your hollow-shaft motion requirement with our engineers.
Share your load, speed, wiring, encoder and installation requirements for product selection and integration support.
Contact us
Would you like to learn more about our solutions?
We would be happy to advise you—personally, competently, and tailored to your requirements.
Perfection in a new dimension
Further Information
Short delivery times available for selected product configurations.
The TP+ HIGH TORQUE enables maximum torque density and maximum torsional rigidity—ideal for demanding applications with dynamic load changes and high positioning accuracy.
alpha Advanced Line gearboxes with increased durability and food-grade lubrication available.
The TP+ for coordinated pinion-rack systems for medium to high requirements. Typical areas of application in wood, plastic, and composite processing, in machining centers, or in automation.
With cynapse® and smart services, you can unleash the full potential of your drive system: sensor data is processed, visualized, and analyzed intelligently. Find out how the combination of gearboxes with cynapse® and our Smart Services can make your digital production faster, safer, and more efficient.
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