EAS torque-limiting clutches for low temperatures

Raw materials extraction in Siberia and Mongolia at daytime temperatures of far below zero degrees Celsius presents enormous challenges to machines and all their components. Standard designs quickly reach their limits here. Your breath crackles and freezes; you have the sensation of walking over broken glass as you go over the snow, and truck engines run continuously from October through to April, day and night, otherwise they would freeze up. In Siberia, the cold dominates major parts of everyday life; the temperatures can drop during the nine winter months to -50degC. Here lie not only the coldest inhabited locations of the earth - Siberia, like Mongolia, is one of the regions of the world most rich in raw materials.

Machines, which are deployed there for the extraction and preparation of raw materials, such as coal and ores, are subjected to extreme conditions. Cold-resistant constructions are required. Helmut Kleinheinz, Sales Manager at mayr power transmission explains: "With high-strength, through-hardened components, cold weather embrittlement increases the risk of component breakage; there is hardly any specialist information available for reliable theoretical dimensioning of these components. This means that further queries must always be made for applications in low temperature areas. Reliable statements can only be made if the constructions are also tested under the conditions which await them in real application cases".

EAS-quality element clutches by mayr power transmission are produced from high-quality materials as a standard measure, and feature hardened functional surfaces - only in this way can the required triggering accuracy and lifetime be achieved. Like all other standard clutches on the market, they are not designed for use at exceptionally low temperatures. To be able to offer reliable, technically proven products for extreme conditions, mayr power transmission has now developed a low-temperature design, and has carried out extensive practical tests.

Helmut Kleinheinz explains: "Our company has comprehensive know-how in development and construction, and can make use of state of the art and unique testing facilities." Using these tests, the tried and tested EAS-element clutches can be modified so that they are able to withstand the extreme cold with their usual robustness.

Mayr power transmission has a diverse spectrum of test benches, using which all products can be subjected to comprehensive functional inspections. Gnter Hable, Design Engineer, says: "For low-temperature applications, the modified EAS-element clutch/Size 0 was tested on an inertia dynamometer with connected climatic chamber at -48degC." Adjusted to a torque of 2400Nm, the clutch was able to withstand 100 overload cases at high speeds without suffering damage. So that the climatic chamber could be kept closed throughout the proceedings, re-engagement took place automatically via an integrated pneumatic engagement device.

In addition, this engagement device was also used to simulate incorrect operation, in order to provoke high impact loads on the components. Application errors were for example caused through re-engagement under differential speeds, i.e. in the run-out phase on already-triggered clutches. In particular in low temperature operation, it has been observed that the application must be considered as a whole in order to ensure the correct integration of the overload clutch into the drive line. At very low temperatures, line-specific characteristics can have large additional effects. For this reason, mayr power transmission always carries out a risk and application inspection together with the customer.

The trials carried out in the climatic chamber prove that the special-design EAS-element clutch by mayr power transmission is capable of use at very low temperatures down to -48degC. In general, these overload clutches provide overload protection for drives with very high torques in a compact construction space based on individual elements. They are suitable as torque limiters for heavy and fast-running drives, and permit large flywheel masses to slow down freely in case of overload. In normal operation, the positive-locking EAS-element clutches transmit the set torque backlash-free with high precision and, in case of overload, react with accurate switch-off accuracy.

To learn more about the low-temperature EAS-element clutches, please visit www.mayr.com.