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CLUTCHES, BRAKES & COUPLINGS CHOOSING THE RIGHT FLEXIBLE SERVO COUPLING FOR
HIGH-TORQUE APPLICATIONS Matching high-torque applications with the ideal servo coupling
demands careful consideration of several factors, including torque and misalignment capabilities, speed requirements, and spatial constraints. Ruland offers a range of high-torque servo couplings – bellows, disc, and slit – each designed to address these factors in unique ways
expense of misalignment. They are comprised of two aluminium hubs, and a flexible centre element called a bellows. The thin walls of the stainless-steel bellows flex while remaining rigid under torsional loads, giving bellows couplings high rigidity to transmit position accurately in the most demanding applications. Bellows couplings are designed for applications
B
requiring precise rotation and dynamic motion, making them an ideal choice for the most demanding servo-driven applications.
DISC COUPLINGS Functionally, disc couplings are close to bellows couplings but have slightly more misalignment capabilities at the expense of torque and stiffness. They are available in two styles. The single disc style is comprised of two aluminium hubs mated to stainless steel disc springs. It is a compact design with equivalent torque and higher stiffness than double disc styles. Designers must be careful when using a single disc coupling, as they have no accommodation for parallel misalignment. Since the torque values are the same, the primary benefit of using a single disc coupling is for space efficiency. Double disc styles feature two aluminium hubs, a centre spacer, and two sets of disc springs. This design allows the coupling to function like a double cardan u-joint, with each hub operating independently. Additional disc springs reduce stiffness while maintaining consistent torque compared to the single-disc style. Double disc couplings can accommodate all forms of misalignment, making them the preferred disc coupling choice for designers.
SLIT COUPLINGS Slit couplings are ideally suited for applications that require precise positioning and demand a balance of torque, stiffness, misalignment, and high-speed capabilities. This combination of performance characteristics makes them a suitable interchange for couplings such as single disc, which has misalignment and speed limitations.
ellows couplings have the highest torque and torsional stiffness capabilities in the Ruland flexible coupling offering at the
FEATURE
Disc, bellows and slit couplings from Ruland have high torque for use in precision systems
“When selecting a high-torque coupling, it is critical to understand all
factors to make the right choice”
Slit couplings are available in long and
short styles. Short styles have higher stiffness, while long ones have increased misalignment capabilities. Speed is a primary differentiator with slit couplings compared to the other high-torque couplings. Bellows and disc couplings max at 10,000rpm. Slit couplings, in comparable bore sizes, have speed capabilities up to 30,000rpm.
SPECIFYING THE RIGHT COUPLING When selecting a high-torque coupling, it is critical to understand all factors to make the right choice. Each coupling style brings its own set of strengths and weaknesses, tailored to meet specific high-torque challenges. Bellows couplings provide Ruland servo couplings’ best size-for-size torque capabilities with limited misalignment capabilities. Disc couplings have higher misalignment than bellows couplings with slightly reduced torque capabilities. Slit couplings have better misalignment and can fit in more confined spaces than a disc or bellows coupling. Choosing the proper coupling allows the system to maximise its performance.
Ruland Manufacturing Co.
www.ruland.com
Acorn Industrial Services T: 0800 8766 441
www.acorn-ind.co.uk/ruland
JULY/AUGUST 2025 DESIGN SOLUTIONS 59
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