Nabtesco's new short-strain wave gears increase power density

Strain wave gears are widely used in robotics, medical systems and precision positioning where compact size and zero backlash are required. Nabtesco has expanded its portfolio with new short-build strain wave gears that increase torque density and service life without enlarging the installation envelope.

Higher torque density within the same dimensions
Conventional short-build strain wave gears are approximately 65% shorter than standard designs, making them suitable for compact joints and axes in humanoid robots, cobots and exoskeletons. The trade-off has typically been reduced torque capacity and shorter service life compared with longer variants.

The new Nabtesco short gears are specified to deliver 120% power density and 140% service life at identical size compared with conventional short-build designs. The rated service life increases from the market standard of 7,000 hours to 10,000 hours.

Higher rated torque also raises repeatable peak torque, acceleration torque and limit torque for emergency stop, ratcheting, buckling and collision scenarios by nearly 20%. For design engineers, this enables smaller gear sizes or lighter adjacent structures while maintaining required load margins in dynamic robotic axes.

Where axial space is limited
The short gears target applications where axial installation length is restricted but torque requirements remain high. Examples include end-of-arm joints in humanoid robots and cobots, wearable systems such as exoskeletons, and compact actuators in medical devices.

Medical engineering applications cited include surgical robots, dental milling machines and detector or optical adjustment mechanisms in imaging systems. Additional uses extend to industrial robots, positioning and rotary axes, machine tools and watch production.

In robotics and automation systems integrated into a digital supply chain, higher torque density and longer service intervals can reduce downtime and improve overall equipment availability.

Hollow shaft configuration and torque range
The new short gears cover a torque range from 4.5 Nm to 115 Nm and are available as hat-type gears (HTG) and cup-type gears (CTG). All variants feature a hollow shaft, providing internal routing space for cables, hoses and media lines, which supports compact mechanical layouts.

Customisation options include geometry, materials, interfaces and system-level integration. Production takes place at the Ovalo GmbH site in Limburg (Lahn) under automotive quality standards with IATF 16949 certification.

Extending the limits of short-build strain wave designs
By increasing power density and service life while maintaining external dimensions, the new short gears address a known limitation of compact strain wave architectures. The combination of higher torque capacity, improved lifetime and unchanged installation space expands design options for compact, high-dynamic robotic and automation systems.

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