--- title: "Nidec Smart-FLEXWAVE SRH reducer specs" description: "Nidec Smart-FLEXWAVE SRH sensorized hollow-shaft reducer with torque and internal-temperature sensing; distinguish WPU-SRH-BD from bare WPU-SRH." canonical: https://actuatorlist.com/actuators/nidec-smart-flexwave-srh last-updated: 2026-11-01T14:05:43.000Z --- # Smart-FLEXWAVE SRH series (smart strain-wave reducer) by Nidec Drive Technology (Nidec-Shimpo) > Nidec Smart-FLEXWAVE SRH sensorized hollow-shaft reducer with torque and internal-temperature sensing; distinguish WPU-SRH-BD from bare WPU-SRH. ## Specifications | Spec | Value | | --- | --- | | Category | Harmonic / Precision | | Peak torque | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Rated torque | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Max speed | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Gear ratio | 50:1-160:1: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Weight | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Torque density | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Price | quote only: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Price per Nm | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Backdrivable | Legacy catalog placeholder; not a measured family rating. See engineering notes. | | Backlash | Legacy catalog placeholder; not a measured family rating. See engineering notes. | | Voltage | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Peak current | n/a: Family-level catalog value; confirm frame, ratio and variant. Reducer/sensor assembly, not an integrated motor and drive. | | Communication | n/a | | Control modes | n/a | | Encoder | Legacy catalog placeholder; not a measured family rating. See engineering notes. | | Integrated driver | no | | Availability | in production | | Data status | Family-level evidence: confirm variant | ## Size a joint - [Humanoid robot actuators](/guides/humanoid-robot-actuators): **7 joints** with a static torque estimate and the catalog parts that reach it. ## Use cases - humanoid joint - cobot joint - robot arm ## Engineering notes Family-level evidence reviewed October 1, 2026. Manufacturer-published data is not independent bench validation. Examples below are not selected inventory SKUs; existing catalog fields are not replaced with family ranges. ### Manufacturer specifications The sensorized WPU-SRH-BD has a cross-roller-supported flange and hollow input for routing; it is not an integrated motor. [Nidec SRH](https://www.nidec-dtc.com/product/srh-series-wpu-srh-bd/). The [Smart-FLEXWAVE catalog, pages 4–6](https://www.nidec-dtc.com/wp-content/uploads/downloads/catalogs/nidec-smart-flexwave-strain-wave-gear-reducer-catalog.pdf) gives frame 50, ratio 100 nominal 52 Nm, start-stop 107 Nm, emergency 191 Nm and life 7,692 hours at 2,000 rpm input and nominal torque. Sensor data lists 12-bit torque resolution, nonlinearity ±3% FS or less and hysteresis 3% FS or less within rated torque. These do not establish total-system accuracy or output-position repeatability. The 24 VDC supply and 3.0 Mbps half-duplex RS-485 are sensor electronics, not a motor bus or servo protocol. ### Conditions and revision conflicts The [website](https://www.nidec-dtc.com/product/srh-series-wpu-srh-bd/) lists sensor current ≤0.06 A; the [catalog, page 5](https://www.nidec-dtc.com/wp-content/uploads/downloads/catalogs/nidec-smart-flexwave-strain-wave-gear-reducer-catalog.pdf) lists ≤0.1 A. Both are T.B.D.; final consumption is unknown. Catalog ±2°C temperature accuracy is also T.B.D. Frame 35/42 comparison masses 0.72/1.0 kg differ from dimensions/catalog values 0.78/1.05 kg. Certification prose says obtained while the table retains expected-in-2024 wording: request the certificate and scope rather than infer whole-machine compliance. Compensation notation ±0.05FS/°C lacks an explicit percent sign; do not normalize it. ### Engineering inference Catalog frame-specific mass/inertia and sensing can assist identification, but no calibrated simulator package was verified. The [0–80°C sensor measurement/electronics range](https://www.nidec-dtc.com/wp-content/uploads/downloads/catalogs/nidec-smart-flexwave-strain-wave-gear-reducer-catalog.pdf) is not unrestricted reducer ambient or continuous thermal duty. Temperature monitoring is not cooling; ordinary WPU efficiency charts do not explicitly validate SRH-BD. Inference assumes the selected drawing and applicable revision are confirmed. Confidence in model completeness is low; no numerical efficiency, cooldown or precision estimate is defensible from this evidence. ### Unknown / confirmation required Numerical product-specific efficiency, cooling hardware, repeated thermal duty/derating, externally measured loaded output repeatability and calibrated simulation support remain unconfirmed in the reviewed material. Unknown is not zero. Encoder or sensor resolution is not output accuracy. Motor voltage, current and motor constants are not applicable to a reducer alone; select a motor/drive separately. Use the [robot actuator selection guide](/guides/robot-actuator-selection) to define the missing measurements and acceptance criteria. ## Sources - [https://www.nidec-dtc.com/product/srh-series-wpu-srh-bd/](https://www.nidec-dtc.com/product/srh-series-wpu-srh-bd/) - [https://www.nidec-dtc.com/wp-content/uploads/downloads/catalogs/nidec-smart-flexwave-strain-wave-gear-reducer-catalog.pdf](https://www.nidec-dtc.com/wp-content/uploads/downloads/catalogs/nidec-smart-flexwave-strain-wave-gear-reducer-catalog.pdf) - [https://www.nidec-dtc.com/wp-content/uploads/2025/10/Smart-FLEXWAVE\_Catalog\_A1-2025.pdf](https://www.nidec-dtc.com/wp-content/uploads/2025/10/Smart-FLEXWAVE_Catalog_A1-2025.pdf) - [https://www.nidec.com/en/products/news/2024/news1225-01/](https://www.nidec.com/en/products/news/2024/news1225-01/) - [https://www.nidec-dtc.com/smart-flexwave-wpu-srh-hollow-shaft-unit/](https://www.nidec-dtc.com/smart-flexwave-wpu-srh-hollow-shaft-unit/) ## Similar Harmonic / Precision actuators - [EC-A5013-H17-100 (ENCOS)](https://actuatorlist.com/actuators/encos-ec-a5013-h17-100): 142.9 Nm/kg - [EC-A3814-H14-107 (ENCOS)](https://actuatorlist.com/actuators/encos-ec-a3814-h14-107): 138.2 Nm/kg - [LPA-20 (Low Profile Rotary Actuator) (Harmonic Drive LLC)](https://actuatorlist.com/actuators/harmonic-drive-lpa-20): 40.7 Nm/kg - [FHA-14C-100 (FHA-C Mini) (Harmonic Drive LLC)](https://actuatorlist.com/actuators/harmonic-drive-fha-14c-100): 17 Nm/kg - [SHA-CG series (SHA-CG Hollow Shaft Actuator) (Harmonic Drive LLC)](https://actuatorlist.com/actuators/harmonic-drive-sha-cg): n/a ## Machine-readable - JSON: https://actuatorlist.com/api/v1/actuators/nidec-smart-flexwave-srh - Catalog index for agents: https://actuatorlist.com/llms.txt