12V DC 20mm Planetary Geared Stepper Motor with 29:1 Gearbox and Encoder
12V DC 20mm Planetary Geared Stepper Motor with 29:1 Gearbox and Encoder
The Kechen Motor KC-GMP20-20BY25 planetary geared stepper motor combines a 20 mm planetary gearbox, a two-phase permanent magnet stepper motor and a Y245 magnetic incremental encoder. The 29:1 reduction ratio decreases output speed and provides finer mechanical output steps compared with the motor’s native step angle.
This 12V planetary geared stepper motor features a D-shaped output shaft, bipolar winding and separate motor and encoder connections. Its incremental encoder provides digital pulse feedback for external motion monitoring. The assembly can be evaluated for OEM positioning mechanisms, instrument adjustment and automated motion-control applications.
Planetary Geared Stepper Motor Technical Specifications
| Parameter | Specification |
|---|---|
| Brand | Kechen Motor |
| Model | KC-GMP20-20BY25 |
| Motor Type | Permanent magnet stepper motor |
| Product Type | Planetary geared stepper motor |
| Gearbox Type | Planetary gearbox |
| Drive Voltage | 12.0 ± 0.2 V DC |
| Number of Phases | 2 phases |
| Motor Step Angle | 18°/step |
| Gear Ratio | 29:1 |
| Coil Resistance | 20 Ω/phase ± 10% |
| Winding Configuration | 2-phase bipolar |
| Nominal Output Step Angle | Approximately 0.621°/full step (calculated) |
| Gearbox Diameter | 20 mm |
| Gearbox Length | 20.6 ± 0.3 mm |
| Motor Body Length | 18.7 mm |
| Output Shaft Type | D-shaped shaft |
| Output Shaft Extension | 23 ± 0.2 mm |
| Drawing Reference Length | 25 ± 0.3 mm |
| Shaft Diameter | 4 mm |
| Shaft Flat Dimension | 3 mm |
| Front Boss Diameter | 10 mm |
| Rear Projection Diameter | 13 mm |
| Rear Projection Length | 7.5 mm |
| Mounting Holes | 3 × M2.5 |
| Mounting Hole PCD | 15 mm |
| Mounting Hole Spacing | 120° |
| Motor Connector | PHR-4, 4 pins |
| Lead Wire | UL1571, 28 AWG |
| Lead Wire Length | 100 ± 10 mm |
| Connector Reference Length | 15.0 ± 1.0 mm |
| Encoder Model | Y245 |
| Encoder Type | Magnetic incremental encoder |
The calculated output step angle is based on the nominal gearbox ratio. Actual positioning accuracy depends on motor step accuracy, gearbox backlash, mechanical load and drive conditions.
Y245 Magnetic Encoder Performance Specifications
| Parameter | Minimum | Typical | Maximum | Condition |
|---|---|---|---|---|
| Supply Voltage | 3.0 V | 3.3 V | 5.0 V | Vcc |
| Supply Current | — | 28 mA | 40 mA | Vcc = 3–5 V |
| Output Withstand Voltage | — | — | 28 V | — |
| Frequency | — | 10 kHz | — | — |
| Output Leakage Current | — | — | 6.0 µA | Output Hi-Z |
| Operating Temperature | −30 °C | — | +85 °C | Encoder only |
Encoder Resolution and Output
The Y245 magnetic incremental encoder provides digital pulse signals through Channels A and B, with a specified resolution of 3 PPR. The measurement reference, output interface and pulse-counting method should be confirmed during controller integration.
Motor and Encoder Wiring
Motor Connector Pin Assignment
Pin 1: Black — Phase A̅
Pin 2: Yellow — Phase A
Pin 3: Red — Phase B̅
Pin 4: Blue — Phase B
Y245 Encoder Pin Assignment
Pin 1: GND — Ground
Pin 2: OUT A — Encoder Channel A
Pin 3: OUT B — Encoder Channel B
Pin 4: VCC — Encoder power supply
The motor and encoder have separate supply requirements. Verify connector orientation, wiring and encoder signal compatibility before connecting the assembly to a controller.
20mm Planetary Geared Stepper Motor Dimensions and Wiring Drawing

Verify shaft engagement, mounting clearances and connector routing against the approved engineering drawing before finalizing the installation.
Related Product Documents & Downloads
| Document Description | File Details |
|---|---|
| 20mm Planetary Geared Stepper Motor 12V Technical Drawing PDF |
PDF · English · 167KB |
Planetary Geared Stepper Motor Advantages
- Planetary Gear Reduction:
The gearbox reduces output speed and increases available output torque relative to direct motor operation, subject to gearbox efficiency and mechanical load limits. - Finer Mechanical Steps:
The reduction ratio decreases the nominal output movement per motor step. Actual positioning accuracy depends on gearbox backlash and operating conditions. - Incremental Encoder Feedback:
The integrated magnetic encoder supplies digital pulse signals for external motion monitoring and feedback-based control. - Defined Mechanical Interface:
The D-shaped shaft and three-hole mounting arrangement provide specified interfaces for mechanical integration. - OEM System Integration:
Separate motor and encoder connections allow engineers to select compatible bipolar drivers and feedback-processing hardware.
Application and Engineering Considerations
This planetary gear stepper motor can be evaluated for instrument adjustment mechanisms, small rotary positioning assemblies and automated equipment requiring geared motion with incremental feedback.
Application selection should consider output torque, operating speed, acceleration, duty cycle, available installation space and allowable positioning error. Encoder feedback does not eliminate gearbox backlash or automatically prevent missed steps. Final suitability should be established through application-specific sample testing.
OEM and ODM Motor Customization
Kechen Motor supports OEM and ODM project discussions for planetary geared stepper motor assemblies. Application-specific requirements can be reviewed against the existing motor, gearbox, output shaft and encoder configuration.
For engineering evaluation, provide the required voltage, output speed, operating torque, shaft interface, installation dimensions, feedback requirements, duty cycle and estimated order quantity. Proposed modifications and final performance specifications are subject to engineering confirmation and approved sample validation.
Payment and Shipping
Payment
- Payment Terms:
Available payment methods and terms are confirmed during quotation. - Project Confirmation:
Final technical specifications, sample requirements and commercial terms are reviewed before order confirmation.
Shipping
- Shipping Arrangement:
Transportation methods and shipping terms are discussed according to the order destination and project requirements. - Production and Dispatch:
Manufacturing schedules and shipment dates are confirmed after technical and commercial requirements have been agreed upon.
Frequently Asked Questions
What Is the Output Step Angle of This 29:1 Planetary Geared Stepper Motor?
Based on the nominal reduction ratio, the calculated output movement is approximately 0.621° per full step. This theoretical value does not represent guaranteed positioning accuracy because gearbox backlash, motor step accuracy and operating load also affect positioning.
Does the KC-GMP20-20BY25 Include an Encoder?
Yes. The assembly includes a Y245 magnetic incremental encoder with digital pulse outputs on Channels A and B. The specified resolution is 3 PPR. The pulse-counting method and measurement reference should be confirmed during controller integration.
Can the Motor and Encoder Share the Same 12V Power Supply?
The motor and encoder have different voltage requirements. The encoder must receive a regulated supply within its specified operating range and must not be connected directly to the motor’s 12 V supply. A common upstream power source may be used with suitable voltage regulation and circuit design.
What Type of Stepper Driver Is Required?
The motor requires a compatible two-phase bipolar stepper driver. Driver current settings, electrical compatibility and the intended motion profile should be verified during engineering evaluation.
What Output Torque and Speed Can This Motor Provide?
Confirmed output torque and speed test results have not been provided for this specific configuration. These parameters depend on drive conditions, gearbox efficiency and operating load. Validated performance data or sample testing should be requested for the intended application.
Can the Shaft or Gearbox Configuration Be Customized?
Kechen Motor can review application-specific mechanical requirements. Alternative shaft dimensions, gearbox configurations and related modifications are subject to engineering feasibility and sample approval.
Related Motor Specifications
Planetary geared stepper motor | Planetary gear stepper motor | 20mm planetary geared stepper motor | 12V planetary geared stepper motor | 29:1 planetary geared stepper motor | Permanent magnet geared stepper motor | Stepper motor with gearbox and encoder | D shaft planetary stepper motor | 2-phase bipolar stepper motor | 20mm planetary gearbox | Magnetic encoder stepper motor | KC-GMP20-20BY25
Specifications are for reference only. Final parameters should be confirmed based on approved samples and project requirements.




