KX-40 High-torque robot actuatorIndustrial-grade torque.Priced for every joint.
Frameless motor, precision planetary stage, dual absolute encoders, and servo drive, sealed in one joint. Engineered to industrial standards and priced for robots built by the hundred.
Quasi-Direct-Drive Rotary ActuatorKX-40
40 N·m peak. 0.9 kg. Two cables from motion.
A 42-pole frameless motor and a single-stage 9:1 planetary keep the KX-40 backdrivable and impact-tolerant, so your robot can feel contact and control force without a separate torque sensor. Dual absolute encoders and a 40 kHz servo drive are built in, not bolted on.
Industrial-grade, not industrial-priced
Crossed-roller output bearing, hard-anodised housing, ISO 2768-mK machining. Designed for automated production, so the price scales down as your fleet scales up.
Torque density that changes the design
40 N·m peak from a 0.9 kg module. More torque per kilogram means lighter limbs, smaller batteries, and faster robots.
Integrated, not assembled
Motor, gearbox, dual absolute encoders, and servo drive in one sealed IP54 joint. EtherCAT or CAN FD in, precise motion out.
Engineered to the standards you build to
Designed in accordance with IEC 61800-5-2 (STO), IEC 60034-1, ISO 9409-1, and EN IEC 61000-6, so integration and certification of your system go faster.
Questions, answered
Everything engineers and buyers ask before putting the KX-40 in a robot.
What is a quasi-direct-drive (QDD) actuator?
A quasi-direct-drive actuator pairs a high-torque frameless motor with a low gear ratio, 9:1 on the KX-40. The low ratio keeps the joint backdrivable and transparent, so a robot can sense contact, absorb impacts, and control force directly from motor current without a dedicated torque sensor.
How is the KX-40 more affordable without lowering quality?
The KX-40 is engineered for automated, high-volume production from day one. A single gear stage, an integrated servo drive, and a reduced part count remove cost and assembly steps, not engineering margin. Bearings, tolerances, and materials are specified to industrial standards.
Which robots is the KX-40 designed for?
Humanoid robots, quadrupeds and other legged robots, collaborative arms and mobile manipulators, and exoskeletons. Anywhere a joint needs high torque density, backdrivability, and precise force control.
How does the KX-40 integrate into my robot?
Mechanically through an ISO 9409-1-50-4-M6 output flange, electrically through a 48 V DC supply, and over EtherCAT (CoE, CiA 402 drive profile) or CAN FD. STEP AP242 CAD models and the full datasheet are available on request.
Which standards is the KX-40 designed to?
The KX-40 is designed in accordance with IEC 60034-1, IEC 61800-5-1, IEC 61800-5-2 (Safe Torque Off), ISO 9409-1, IEC 60529 (IP54), IEC 60068-2, and EN IEC 61000-6-2/-6-4. These are design references; declarations of conformity and test reports are available on request.
How do I get an offer or evaluation samples?
Email sales@krhsr.com with your application, joint count, and target volumes. An application engineer replies within two business days with volume pricing, sample availability, and lead times.