Robot joints and actuation
smart servo: 0.44 N·m rated / 2.45 N·m peak at 273:1, 51 rpm no-load.
Engineering inference
Fashion Star
Fashion Star RA8-U25H-M Bus Servo
Fashion Star RA8-U25H-M is a dual-shaft 12 V UART bus servo: cored motor, 273:1 all-metal gears, 2.45 N·m (25 kg·cm) stall and 0.44 N·m rated torque, 51 rpm no-load, 12-bit magnetic encoder, UART/TTL up to 1 Mbps with IDs 0–254, 9.0–12.6 V, 63 g, 40 × 40 × 20 mm.
RA8-U25H-MDevelopment boardPrice$35.00aifitlab.com · in stock
Buy at aifitlab.com Overview
Motor essentials
Facts about the complete product. Unknown values remain open design questions.
- Rated voltage
- 12.6 V
- No-load speed
- 51 RPM
- Gear reduction
- 273:1
- Encoder
- 12-bit magnetic absolute (2,048 steps per 360°, 0.176°)
A good fit for
Guidance to help you shortlist. The basis is shown for each recommendation.
No-load speed, rated performance and stall limits describe different operating points. A stall specification is not a continuous operating rating.
3D model & CAD
3D model & CAD files
Generated from the datasheet's dimensioned drawing and measured against it. Download the STEP to check fit in your own enclosure.
- Envelope (L × W × H)
- 40 × 20 × 40 mm
- Verification
- generated
- Envelope complete
- Yes
Torque & control
Torque, speed and control
What the joint can deliver and how the controller talks to it.
- Type
- SMART_SERVO
- Rated / peak torque
- 0.44 / 2.45 N·m
- No-load speed
- 51 rpm
- Encoder
- 12-bit magnetic absolute (2,048 steps per 360°, 0.176°)
- Control
- UART · single-turn angle, multi-turn angle, damping
| Connector | Type |
|---|---|
| bus | PH2.0 3-pin bus connector (GND, VDD, Signal), 200 mm cable |
Rated torque is continuous; peak torque is short-duration. Values with two figures (e.g. 24/48 V) are per supply voltage.
Specifications
Motor performance
No-load, rated-load and stall figures retain their separate test conditions.
- Rated voltage
- 12.6 V
- No-load speed
- 51 RPM
- Continuous rated torque
- 0.44 N·m
- Rated-load speed
- 18 RPM
Stall torque and current are not continuous ratings. Check the duty cycle and starting load when choosing the driver and power supply.
Thermal limits by level
Product operating conditions, chip ambient ratings, package case limits and junction maxima remain separate.
Motor body
- Product operating range
- -10 to 60 °C
Mechanical dimensions
Reported product dimensions may exclude protruding components. Unknown height does not establish a complete clearance envelope.
- Length
- 40 mm
- Width
- 20 mm
- Reported height / thickness
- 40 mm
Attached generated geometry is an approximate envelope. A generated outline does not establish an electrically verified PCB footprint.
Board connectors
| ID / type | Pins | Pitch | Notes |
|---|---|---|---|
| busPH2.0 3-pin bus connector (GND, VDD, Signal), 200 mm cable | 3 | Unknown | — |
Complete structured record
Every available field, including details beyond the summaries. Null means the value has not been established.
Sourcing & files
Supplier offers
US / USD is the target market. Observed price and stock are separate from a delivery quote.
aifitlab.com
US · USD
$35.00Minimum quantity unknown
- Observed stock
- in stock
- Checked
- Oct 20, 2026, 05:31 AM UTC
- Delivery estimate
- Not quoted
This observation is stale or has no verified check time. Recheck with the supplier.
Visit supplier (opens in a new tab)Delivery depends on quantity, postal code and shipping method. A dispatch statement such as “ship today” is not an arrival estimate.
Design files and references
Each source keeps its own verification status. Confirm the part revision and file contents before using it in a design.
Datasheet (opens in a new tab)
Manufacturer reference
Fashion Star RA8-U25-M 25 kg servo — product photo (AIFIT Lab) (opens in a new tab)
Unverified reference
inspected: black and green case, label reads RA8-U25-M 25KG UART Bus Servo 6.0V-8.4V (the 7.4 V variant's label), horns on both sides (dual shaft), 3-pin connector marked - + S; reseller listing photo
STEP (generated from datasheet drawing) — link unavailable
Generated asset
cad_check passed
Generated envelope geometry may also exist for this record. It does not replace manufacturer CAD or a verified electrical land pattern.
Source evidence
Document provenance, retrieval dates and the field groups supported by each source.
Supports: spec.constraints.electrical.supply_voltage_nominal_v, spec.constraints.thermal.operating_temp_max_c, spec.constraints.thermal.operating_temp_min_c, spec.geometry.body_length_mm, spec.geometry.cad.bbox.height_mm, spec.geometry.cad.bbox.length_mm, spec.geometry.cad.bbox.width_mm, spec.geometry.cad.envelope_complete, spec.geometry.cad.mesh_path, spec.geometry.cad.step_path, spec.geometry.cad.verification, spec.geometry.dimensions.height_mm, spec.geometry.dimensions.length_mm, spec.geometry.dimensions.width_mm, spec.geometry.other.weight_g, spec.provides.actuator_type, spec.provides.control_interface, spec.provides.control_modes, spec.provides.encoder, spec.provides.encoder_bits, spec.provides.features, spec.provides.gear_ratio, spec.provides.integrated_driver, spec.provides.motor_type, spec.provides.no_load_speed_rpm, spec.provides.peak_torque_nm, spec.provides.rated_speed_rpm, spec.provides.rated_torque_nm, spec.usage.connectors, spec.usage.pinout, spec.usage.pinout_complete, spec.usage.requirements.other.peak_current_a, spec.usage.requirements.rated_voltage_v
sha256 d8f61080dae18a7871ecdc659113ba4e6412718727149dbfd6b38805177fa940
Supports: offers
FAQ
Fashion Star RA8-U25H-M Bus Servo questions
How much does the Fashion Star RA8-U25H-M Bus Servo cost?
From $35 at aifitlab.com. Prices are observed unit prices before tax and shipping.
What are the Fashion Star RA8-U25H-M Bus Servo dimensions?
40 × 20 × 40 mm. A STEP model is available for enclosure fit checks.
Where does this Fashion Star RA8-U25H-M Bus Servo data come from?
Every value in this record is traced to a source — 2 documents including the board and chip datasheets — with the page and table cited per value. Unknowns are left explicit, never guessed.