---
title: "Harmonic Drive LPA-20 specs"
description: "Harmonic / Precision actuator from Harmonic Drive LLC (Japan). Peak torque 57 Nm, rated 16.9 Nm, weight 1400 g, torque density 40.7 Nm/kg, price quote only."
canonical: https://actuatorlist.com/actuators/harmonic-drive-lpa-20
last-updated: 2026-11-01T14:05:43.000Z
---
# LPA-20 (Low Profile Rotary Actuator) by Harmonic Drive LLC

> Harmonic / Precision actuator from Harmonic Drive LLC (Japan). Peak torque 57 Nm, rated 16.9 Nm, weight 1400 g, torque density 40.7 Nm/kg, price quote only.

## Specifications

| Spec | Value |
| --- | --- |
| Category | Harmonic / Precision |
| Peak torque | 57 Nm |
| Rated torque | 16.9 Nm |
| Max speed | n/a |
| Gear ratio | 51:1-101:1 |
| Weight | 1400 g |
| Torque density | 40.7 Nm/kg |
| Price | quote only |
| Price per Nm | n/a |
| Backdrivable | no |
| Backlash | 0 arcmin |
| Voltage | 48 V |
| Peak current | n/a |
| Communication | CAN, EtherCAT |
| Control modes | position, velocity, torque |
| Encoder | dual absolute encoders |
| Integrated driver | yes |
| Availability | in production |
| Data status | Catalog headline specs spot-checked: confirm revision |

## Size a joint

- [Motor torque calculator](/tools/motor-torque-calculator?solve=power&t=16.9): **16.9 N·m** rated; add a speed for its shaft power.
- [Robot arm torque calculator](/tools/robot-arm-torque-calculator?L=0.4,0.35,0.12&m=1.2,0.8,0.3&a=1.4,0.5,0&p=2): **35.5 N·m** at the shoulder with its 1400 g at the elbow of a 2 kg-payload arm.
- [Humanoid robot actuators](/guides/humanoid-robot-actuators#waist): **4 of 7 joints** within its rated torque, up to the waist at 16.9 N·m.

## Use cases

- humanoid joint
- cobot joint
- robot arm
- surgical robotics

## Notes

Low-profile integrated servo actuator aimed at humanoid/cobot joints and surgical robotics. Combines zero-backlash Harmonic Drive gearing, a brushless servomotor, brake, dual absolute encoders and an integrated servo drive (CANopen/EtherCAT). Gear ratios 51/81/101:1. Continuous torque 6.5 to 16.9 N·m and maximum (peak) torque 34 to 57 N·m depending on ratio; recorded values are the top-of-range (101:1) figures. Weight about 1.4 kg. Rated supply voltage 48 VDC (confirmed via distributor listing). torque\_density computed from peak 57 N·m over 1.4 kg. Repeatability not published in accessible sources, so left null. Quote-only pricing.

## Sources

- [https://www.harmonicdrive.net/products/integrated-actuators/integrated-actuators/lpa-integrated-servo-drive](https://www.harmonicdrive.net/products/integrated-actuators/integrated-actuators/lpa-integrated-servo-drive)
- [https://www.harmonicdrive.net/\_hd/Content/documents1/Group%20Integrated%20Brochure.pdf](https://www.harmonicdrive.net/_hd/Content/documents1/Group%20Integrated%20Brochure.pdf)
- [https://humanoidroboticstechnology.com/company/harmonic-drive-llc/lpa-20-integrated-servo-actuator/](https://humanoidroboticstechnology.com/company/harmonic-drive-llc/lpa-20-integrated-servo-actuator/)
- [https://www.directindustry.es/prod/harmonic-drive-llc/product-4567321-2832039.html](https://www.directindustry.es/prod/harmonic-drive-llc/product-4567321-2832039.html)
- [https://www.roboticstomorrow.com/news/2026/07/06/harmonic-drive-advances-surgical-robotics-supply-with-innovative-lpa-20-compact-actuator-control-component/26804](https://www.roboticstomorrow.com/news/2026/07/06/harmonic-drive-advances-surgical-robotics-supply-with-innovative-lpa-20-compact-actuator-control-component/26804)

## 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
- [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
- [CHA series (Hollow Shaft Servo Actuator) (Harmonic Drive (Harmonic Drive SE / LLC))](https://actuatorlist.com/actuators/harmonic-drive-cha-series): n/a

## Machine-readable

- JSON: https://actuatorlist.com/api/v1/actuators/harmonic-drive-lpa-20
- Catalog index for agents: https://actuatorlist.com/llms.txt