Harmonic Gearing Technology (HGT)
NAC Drive Systems, Inc., a wholly owned subsidiary, provides harmonic gearing and controls for robotics, defense, communications, medical and a wide array of industrial applications.

Harmonics are critical drives to many industries including robotics, semi-conductor, aerospace, and defense. Additionally, harmonic technology is widely used in motion control applications where precision, long-life, compactness, and reliability are important features. We operate in both the commercial and defense industry segments. Within the commercial segment we currently sell to the following industries, among others: robotic, printing, corrugated, semiconductor, and health care.

Harmonic gearing technology ("HGT") is very unique, and in its most basic form includes a flexible gear, elliptical ball bearing, and rigid outer spline. This design offers several unique, advantageous properties that have made HGT nearly irreplaceable in many applications. HGT advantages include: light weight, high mechanical advantage, precise smooth motion, compact size, high efficiency, high reliability for critical applications, consistent performance over time, speed, and load profiles, and suitability for commercial, military and space flight applications.

The Company believes that there are very high barriers to entry in the market, including proprietary designs and engineering, company history, product validation, customer access, metallurgical processing, work holding and tooling, vendor access, and manufacturing know how, quality and testing know how.  NAC Drive Systems partners with CTKM Beijing Harmonic Drive, Ltd., the national supplier of harmonic technology for the China space program.

NAC Global Technologies has strategic initiatives to develop and expand our application scope into emerging clean energy and advanced force sensing robotic applications

NAC’s core HGT technology is ideally suited to a wide array of positioning applications including emerging applications in solar collector power generation.  HGT’s zero backlash, high efficiency attributes make it ideal for precise positioning at a distance and low power consumption; thereby, increasing the overall net power generated.  The company has an active initiative, based upon industry requests, to develop high speed, high volume automated production lines high volume applications. NAC’s decades of experience in the design and manufacturing HGT based assemblies positions the company well to meet industry needs and be a valuable partner to solar power companies.

Today, no known companies are focused on developing and commercializing the unique properties of HGT for the wind power industry. The current fixed speed gearbox technology is plagued by reliability issues, high costs, and heavy weights. It is a driving factor to move towards PMG’s (Permanent Magnet Generators). In a typical 3MW turbine, the traditional planetary gearbox might cost 400,000 USD and weigh over 20,000 kg. Typically, three (3) stages are necessary to increase the speed; and thus, they have many moving parts. The inertial is high, so the cut in torque is also proportionately high. The current designs utilize standard involute tooth forms which generate heat and wear with every revolution; thus releasing metal particles into the lubricants. Frequent lubricant maintenance is necessary increasing environmental concerns, and gearbox replacement is often required in as little as 2-4 years. The current variable speed technology eliminates the gearbox and drives but, that method results in a reliance on rare-earth materials and greatly increases the diameter and weight of the generator. The planned harmonic gear technology is a single stage, high ratio, high efficiency speedncreaser that resolves the gearing issue of the wind power industry.


The potential impact is enormous on the field of wind power generation. The use of harmonic gearing can eliminate one primary reason the industry is pushing towards direct drive generators with permanent magnets, that being failures and maintenance costs of traditional gearboxes. The expected cost, size, and reliability of the harmonic gearbox can eliminate the need to move to direct drives. The unique harmonic gearing solution will significantly reduce drive train cost, especially when coupled with an AC based, variable-speed generator as planned. The harmonic gearing solution will reduce weight and size. As the technology will allow for ratios over 200:1 in a single stage, only one stage is required and moving parts are dramatically reduced. Harmonic gearing is highly efficient and generates very little heat; therefore, lubrication systems, maintenance, and costs may be reduced. The advanced harmonic gearing technology integrated with new and advanced variable speed, AC based generator technology can provide superior performance in the areas of initial equipment cost, installation costs, maintenance costs, reliability, kWh with zero rare-earth permanent magnet content.

Similar in basic design and smaller in scale, the company has design concepts or a variety of energy generation and capturing devices utilizing its core HGT technology.


The Company is seeking to further expand into the Health Care Market with specialized drives for medical/surgical robots and prosthetic limbs. We believe many of the characteristics offered by NAC’s core drive technology may offer benefit in these applications. NAC’s Flow Joint is a joint that allows senses for Prosthetics. A Flow Joint is a joint that allows senses and energy to flow bi-directionally through the joint. This development may lead toward sensory feedback and a more realistic function. We believe they can be developed to allow for a more natural use while saving power consumption and perhaps even for generating power to recharge the batteries. NAC is positioned well for this initiative as its drive technology is already bi-directional and allows power and energy to transfer though it in both directions, and existing core competency includes precise force sensing technology and product lines of semi-conductor strain wave force transducers.

In our current industrial control systems, force sensors are located in the machine for closed loop feedback to the drive. In a Flow Joint, the concept is to build sensors into the drive. Part of the Flow Joint concept is to break down basic articulation functions into simple linear and rotational reactionary forces, and providing a means to measure and translate them into electrical signals, all within the joint drive design. Both segments, the drive and sensing, are within the company’s existing core competencies. Challenges include miniaturization and manufacturing techniques amongst others.

Thought control of prosthetics is not within our business scope; however, many of the other factors are. NAC drives, in miniaturized form and specialized for the application may provide a path forward to advance the state of the art.


NAC GLOBAL TECHNOLOGIES - 4720 Salisbury Road - Jacksonville, FL 32256 - Phone: (904) 493-6496 - Fax: (904) 339-9241