New hollow shaft actuators from Harmonic Drive

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Harmonic Drive is announcing new lightweight Hollow Shaft Servo Actuators. Used in industrial applications where high accuracy, high torque and low weight are essential, the new CHA-14 and CHA-17 actuators go one step further by introducing a central hollow shaft. This aids original equipment manufacturers (OEMs) in minimising complexity in varied industrial applications such as offshore oil and gas, broadcast, automation and robotics.

Harmonic’s CHA-Series feature a versatile hollow shaft – claimed to be the largest available on the market. This makes it easy to pass power supply cables, shafts or laser beams directly through the servo actuator. OEMs can now simplify application designs and ultimately save considerably on development costs and assembly time.

The new CHA-14 and CHA-17 enhance the servo actuator range provided by Harmonic Drive UK. With over 40 years’ experience in providing innovative and well-engineered products to industries from aerospace and military to industrial and automotive, Harmonic Drive specialises in precision geared systems that offer zero backlash, high single stage gear ratios and high torque capacity.

These new actuators target the increasing demand by the industry for more compact, powerful and cost-effective machine tools. In conjunction with the integrated hollow shaft, robustness is maximised by using high-capacity tilt-resistant output bearings to allow direct mounting of the load.

Graham Mackrell, managing director of Harmonic Drive UK, explains: “Zero backlash gears with high torsional stiffness that offer high precision, accuracy and repeatability, whilst being rugged enough to perform in harsh conditions, are rare. The fact that the BBC’s frozen planet documentary series has used our gears in camera rigs on 6-month-long filming missions in the Antarctic, is testament to the reliability and build quality of our precision components.

“The CHA-14 and CHA-17 Hollow Shaft Actuators utilise a specially designed compact synchronous motor with a concentrated motor winding. The windings are also encapsulated using a vacuum process to further increase the power density, making the actuators perform reliably in tough conditions as found in homeland security applications.

“We are especially proud of our new CHA-14 Series Hollow Shaft Actuator which was placed as the fifth winner in the SPS Drives product list, competing with products from a field of 70 companies. The reason for this success can be found in our product development process. We looked at what was required to build a highly robust and accurate actuator, took existing components and improved weight, volume and efficiency characteristics.”

Using pre-stressed, zero backlash, four-point bearings as flange bearings allows them to be directly assembled onto the machine housing. The resultant structure allows excellent parallelism, perpendicularity and coaxiality of the actuator to the machine housing.

In addition to the hollow shaft, key performance traits include IP65 ingress protection from dust and jets of water, increased continuous torque, the inclusion of a multi-turn absolute encoder and a resolver for use in harsh and extreme environments. The range also includes optional integrated holding brake and air-purge connection.

Mackrell continues: “Ease of installation was essential to the development of the CHA series. The actuators can be easily integrated with YukonDrive servo controllers or alternatively the actuator is compatible with almost any servo controller on the market.”

To learn more about the CHA-Series hollow shaft actuators, please go to

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