Power transmission component developer KTR has extended its line of lightweight torque limiters overload couplings by adding two new sizes.
The company explains that the overload couplings are suitable for shaft diameters of up to 15 mm, and up to 60 mm, with a maximum release torque of 14 Nm and 550 Nm respectively, and that respectively they weigh 120 g and 3 kg with an outside diameter of 42 mm and 116 mm.
KTR exhibited the backlash-free overload couplings at the Hanover Fair 2017 last month.
KTR brake systems product manager Fabian Liekam says the backlash-free Syntex-nc overload couplings offer a hybrid design and are manufactured in conjunction with a wear-resistant surface coating. The design is based on a backlash-free, positive locking ball-latching principle separating the input and output in milliseconds when exceeding the present torque.
The torque limiter is available in two functional systems: the ratchet design where coupling re-engages automatically after removing the overload after 15º, and the synchronous design where coupling re-engages after 360º. He notes that, in both cases, the coupling is automatically ready for operation again.
With the expansion, the Syntex-nc is available in five sizes for shaft diameters from 8 mm to 60 mm and release torques from 2 Nm to 550 Nm.
Main applications include machine tools and packaging machines, control and positioning engineering as well as special machine construction.
The standard version will be used in direct drives. However, an integrated deep groove ball bearing offers the possibility of a direct assembly of pulleys, special flanges or further components.
He explains that the Syntex-NC is additionally available in connection with the backlash-free and flexible Rotex-GS jaw-type coupling as well as the backlash-free and torsionally stiff Toolflex metal bellow-type coupling. Further, it is also possible to combine the torque limiter with KTR’s Dataflex measuring shaft.
The company has also added the BoWexElastic HE line in two of its portfolios. The new couplings are available in different Shore hardnesses and suitable for high-performance drives of up to 5 000 kW and were also exhibited at the Hanover Fair 2017.
The BoWex-Elastic HE is a flange coupling with high torsional flexibility consisting of a circular elastomer. He says the rubber element is made of vulcanised natural rubber and stressed for torque-to-bore ratio.
Liekam explains that it reduces the torsional vibrations occurring in the drivetrain as well as the cumulative forces. Also, owing to different elastomer hardnesses, the flange coupling can be adjusted to the respective application for a resonance-free operation. The plug-in coupling hub is designed according to the BoWex curved-tooth gear principle and compensates for axial, radial and angular shaft displacements.
The company has expanded the line by adding 240 HE and 275 HE sizes, making the coupling suitable for drives of up to 4 000 kW and 5 000 kW, transmitting torques of up to 32 000 Nm and 45 000 Nm. Possible application fields are gensets, pumps and compressors, as well as high-performance stationary and mobile drive systems.
Further, he points out that KTR has developed a floating calliper brake, which forms part of the XS series. It is optionally available with an hydraulic or electromechanical operating principle and both can be operated in an active and passive mode. The brakes are suitable for sub-zero applications with temperatures ranging down to –40 ºC.
He explains that the new XS series brake calliper combines the housing, spacer plate, and counter plate as one piece and is made of special lamellar graphite nodular iron. This is what makes the floating calliper brakes suitable for sub-zero applications with temperatures ranging down to –40 ºC. All other components such as pad retainers, pistons and guide pins are made of steel.
The brake pads are made of an ‘organic mixture’ or ‘sinter metal’, he explains, and can easily be replaced by one person. Depending on the application’s preference and basic conditions, the XS brake calliper can be operated either hydraulically or electromechanically, with clamping forces up to 15 kN being generated in the passive design and 16.5 kN in the active design. The brakes are each mounted to the respective machine by two screws of size M16.
“Since the brake calliper is made out of one piece of material, there are no more exposed contact surfaces. In doing so, we improved the brake’s corrosion resistance. In addition, the one-piece design allowed us to extend the guide pins and double the number of bushings, improving the brake’s floating operation and the efficiency of transmission of force from the calliper to the base plate. This makes the brake even stronger,” explains Liekam.
He concludes that the floating calliper brakes series is intended for applications in the most demanding environmental conditions, both above or underground, onshore or offshore and can be used both as service brakes, for high numbers of cycles, and as holding brakes.