TKH Torque Motors

Torque and Spindle Motors

Super High torque density, thin ring torque motor series

The TKH series is designed to be entirely manufactured in Italy with a mostly local supply chain and internal production. This provides a shorter and more reliable supply chain, increased flexibility and faster response times .

Designed to deliver exceptional performance in peak and continuous torque density, low to medium speed, with fast positioning ability. Equipped with cutting-edge technology such as an innovative electromagnetic circuit and magnet dovetail positive locking, the TKH series can handle even the most demanding applications requiring both low speed and fast transient positioning.

The accurate magnetic circuit design and strict manufacturing tolerance design ensure low cogging ripple and smooth torque delivery.


TKH Catalog 22.56 MB 2567 downloads


    The highly modular design is optimized to guarantee faster availability of parts, reducing the risk of stock shortages and downtime .


    • 11 different TKH sizes, split into 145 variants
    • Active stator length stack up to 200 mm
    • External frame diameter options from 230 mm to 1030 mm
    • Internal rotor / shaft diameter OPTIONS from  135 mm to  870 mm
    • Continuous rated torque values ranging from 108 Nm to 18480 Nm.
    • Peak torque up to 34567 Nm
      Max speed up to 2300 rpm






    Engineered to excel in demanding applications, the TKH “frameless” motors are designed to be built into the equipment they are intended to drive, and to ride on the bearings of the equipment. They feature a three-phase stator, vacuum encapsulated in epoxy, assembled into a steel frame which carries the male part of the cooling circuit and its seals, and rare earth magnets and steel rotor, with an overall IP 20 protection rating. Actual motor protection is realized by the application.

    TKH motors are designed to provide the best mechanical characteristics, with the most efficient cooling and the smallest machine footprint. These are obtained with a special high density winding and a new high thermal conductivity vacuum potting epoxy resin.

    Stator characteristics

    The TKH motors are the perfect choice for applications where compact size, high efficiency and absolute reliability are of the utmost importance. The TKH series boasts a new encapsulant (currently undergoing Class H development) with superior resistance to thermal cycling, exceptional thermal transfer and high peak temperature capability. This results in unparalleled thermal efficiency, making it an ideal choice for precision machines that are sensitive to thermal drift.

    The TKH motors are engineered with a state-of-the-art winding concept, featuring surge-hardened Class H insulation, specifically designed for high ΔV/Δt according to IEC 60034-18-42:2017 Class 3 (Severe) standards. This reinforced insulation allows operation with DC bus voltage up to 750 Vdc, making the TKH series the perfect solution for demanding servo drive applications.

    The TKH series undergo rigorous testing to ensure the highest level of safety and performance, including a 4.5 kVdc phase-to-ground insulation voltage test for 60 seconds as well as 100% partial discharge testing.

    TKH motors are equipped with a winding star point, which can be used for filtering purposes. The power leads are insulated with Radox 155, a material known for its exceptional mechanical and thermal resistance properties. This insulation ensures that the device operates reliably under a wide range of temperatures and conditions, making it a suitable option for various industrial and commercial applications. TKH motors are equipped with two PT 1000 and three PTC 155 sensor probes.The PTCs are placed on each phase and are used for protection, while the redundant PT 1000 sensors are intended for temperature monitoring and are double insulated to protect the drive circuitry.

    Rotor characteristics

    The permanent magnet rotors of the TKH series are isotropic, surface magnet type. Magnets are fastened mechanically on a magnetic circuit optimized to minimize cogging and ripple. This design provides for a very thin ring rotor. The coated FeNdB high temperature magnets ensure stability up to the max class temperature.The rotor to machine mechanical interface is realized out of machined C40 steel, uncoated and manufactured to Grade 8 tolerance, not balanced. It is optimized for continuous peripheral speed of up to 10 m/sec.

    Cooling frame

    The stator frame carries the inner part of the cooling circuit. The special cooling circuit is designed for maximum heat exchange with minimal pressure drop and efficient, uniform temperature control of the stator. The cooling circuit is completed by inserting the stator, complete with the peripheral O-rings, in the cylindrical assembly cavity of the application. Cooling fluid can be either water-glycole, with a ionic stabilizer or oil, with some derating. Care must be taken to avoid galvanic corrosion in the cooling circuit. Refer to TK manual for specific guidelines. The motor is equipped with one or two O-rings on each side to seal the cooling circuit and an intermediate leakage collection ring to protect against damage in case of O-ring failure, ensuring reliable operation.

    Standard frames are machined out of C50 steel, normalized and phosphate conversion coating protected. This enhances corrosion resistance and improves performance while extending the service life of the system. Standard tolerance grade 8, even higher accuracy can be supplied on demand.

    All motors are equipped with 1 m power and sensor cables. This allows for easy integration and installation in various applications. Longer cables are discouraged as they increase the whole motor vulnerability. In 30 years of frameless motor production, cable damage was confirmed as by far the N. 1 cause of unrepairable failure.

    For specialized applications, oil cooling is also an option. While not as thermally efficient, oil cooling has good dielectric properties and provides added protection against leaks.
    When oil cooling is chosen, a 10% S1 torque derating is to be expected, as well as increased coolant flow and pressure drop compared to water/glycol systems. If oil cooling is required, a custom specification will be issued which will define performance derating and flow requirements.

    Assembly of the rotor into to stator is a critical process, due to intense magnetic forces and potential high voltage generation. This process needs special care and cannot be approached without specific preparation and tooling. Please refer to the TKH series user manual for detailed instructions and prescriptions.