What is Flexible Shaft Coupling? Types of Flexible Shaft Couplings in 2025

1. Concept and Role of Flexible Shaft Couplings

A flexible shaft coupling is a motor shaft coupling, flexible coupling or also known as flexible couplings.
It is a mechanical device used to connect two rotating shafts together, usually at the output of the motor and the input of the machine or pump. Its characteristic is the ability to absorb vibration, reduce vibration, and compensate for the deviation between the two rotating shafts.
– Smooth and stable torque transmission.
– Reduce vibration, create durability for the system.
– Protect the parts that can absorb transmission.

See more article: What is Elastic Shaft Couplings? Applications of Elastic Shaft Couplings

2. Classification of Industrial Flexible Shaft Couplings

2.1. Rotex – KTR couplings. Widely used national products

Why is this called a national product because the keyword “Rotex coupling” is very popular in the shaft coupling market?
– With the advantages of compact design, torque, and many sizes to meet many different requirements, they are widely used and known by many people.
– Therefore, Rotex shaft coupling products are also widely counterfeited on the market. Therefore, to buy genuine products, customers should choose the right manufacturing brand, which is KTR from Germany.
– For the Rotex flexible shaft coupling line, there will be 2 groups: Rotex Standard couplings for common applications and Rotex GS couplings for servo applications.

Rotex Standard couplings
– Have very high stiffness, maximum torque up to 56000 Nm.
– Couplings are made from high quality materials such as stainless steel (Rotex Inox), aluminum (Rotex ALU), cast iron (Rotex GG), ensuring durability and long life.
– Components used for engines with a capacity of over 1000 kW.
– Rubber gaskets for couplings are designed in the shape of a star fruit flower.
– KTR Rotex Standard couplings come in many different sizes: Rotex 19, Rotex 24, Rotex 28, Rotex 38, Rotex 42, Rotex 48, Rotex 55, Rotex 65, Rotex 75, Rotex 90, Rotex 100, Rotex 110, Rotex 125, Rotex 140, Rotex 160, Rotex 180.

Rotex GS Couplings
– With compact design and high torque.
– Ambient temperature can be from -50ºC to +150ºC (depending on spider damper).
– The Elastomer Spider of the shaft coupling is designed similar to the Rotex coupling damper rubber washer, Shore hardness standard 95/98 Sh-A (red) and 64Sh-D-H (green).
– The device is used in precision transmission, reducing vibration. At the same time, it compensates for radial displacement, axial displacement and angle, does not require regular maintenance, easy to disassemble and install as a plug-in.
– Low cost components, cut off leakage current due to insulating spider damper, easy to check visual wear and estimate service life, complies with ATEX standards.

2.2. TNM Normex – Ringfeder Couplings

This is Ringfeder’s outstanding flexible coupling line and is also widely used.
TNM couplings are formerly known as Nor-Mex couplings. This product has many variations to suit different applications: TNM E, G, H, LE, KE, LG, KG, EBT, GBT, etc.

TNM E Couplings

2.3. TNR Couplings. Used for generators, diesel engines according to SAE J620 standard

– Ringfeder TNR Couplings (Torsional High Flex Couplings TNR) have rotational speed: from 1500 rpm to 6000 rpm.

Ringfeder TNR Couplings in Diesel Engines

– Torque: from 160Nm to 68000Nm.
– Working environment: -50oC to +130oC.
– TNR Couplings consist of 6 main parts: SAE flange and outer tube + oil seal (o-ring) + shock absorber rubber + shaft + protective cover + screw, in addition there is a cone lock bushing part that only uses TNR 2425.1 couplings.
– TNR coupling shock absorber rubber is made from natural synthetic rubber and polyurethane with different standard hardness.
– Easy to replace worn parts without moving the shaft or machine base.

2.4. Rathi-Lovejoy RRS Couplings. Long Couplings

– Couplings are available in 8 different sizes to suit different drive applications: RRS 95, RRS 99, RRS 100, RRS 110, RRS 150, RRS 190, RRS 225, RRS 226.
– Rathi-Lovejoy flexible couplings are flexible couplings. Designed with a unique wrap around the connecting part in Nitrile rubber, the coupling eliminates the need to dismantle the connected equipment during inspection or replacement of components – a major benefit when machine downtime can be greatly increased
– Combined with a wide range of pre-drilled hubs, modular hub designs and gasket options, Rathi-Lovejoy couplings excel in quality, flexibility, speed of installation and maintenance.
– Power: 113 kw/100 rpm. – Maximum drilling hole up to: 115 mm.

See detailed RRS coupling specifications here

2.5. Roflex couplings. N-Eupex interchangeable product

– Roflex-SH shaft couplings are torsional flexible and safe with a compact design.
– DIN 740 standard couplings are created through cracks.
– Short shaft couplings consisting of three parts used to transmit torsional vibration reduction forces.
– The couplings are easy to assemble/disassemble through four screws.
– Torque: 80Nm – 5000Nm.
– Rotation speed: from 3000 – 7500 rpm.

This product comes from the KTR brand, made in Germany. The product is always available at Dai Hong Phat warehouse, you can use it as a complete replacement for N-Eupex.

See more article: Applications of Roflex coupling in industries
See more article: Why choose Roflex-SH coupling to replace N-Eupex A coupling

3. Advantages & Applications of Rubber Shaft Couplings

– Absorb vibration, protect the transmission.
– Compensate for shaft misalignment during installation.
– Reduce operating noise.
– Increase service life and operating efficiency.
– Low maintenance costs.

Flexible shaft couplings are widely used in many industries:
– Water pumping systems, vacuum pumps.
– Industrial production lines.
– Electric motors and air compressors.
– Automation equipment: robots, CNC machines.
– Cement, steel, paper and packaging industries.

4. Reputable brands providing flexible shaft couplings

5. Beware of fake flexible shaft couplings – Choose a reputable unit

Flexible shaft couplings are indispensable equipment in the transmission systems of mechanical, manufacturing, and processing factories… However, according to the report of the General Department of Market Management, each year Vietnam records hundreds of violations related to counterfeit industrial goods, including many cases of counterfeit shaft couplings. These products are often 20-60% cheaper, but come with the risk of breakage, large vibrations, even causing equipment fires and explosions, disrupting production and causing damage of up to hundreds of millions of VND.

In reality, many businesses, because of their desire for cheapness or lack of verification, have unwittingly contributed to counterfeit goods. Therefore, choosing a supplier with genuine authorization certificates, transparent origin and clear warranty policies is a vital factor.

In the Vietnamese market, Dai Hong Phat is currently the official authorized unit of many famous expansion joint brands from Europe such as KTR – Germany, Rathi – India, committed to 100% genuine goods, with full CO, CQ and accompanying technical policies. This is a reliable choice for businesses that prioritize quality and safety.

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With more than 15 years of experience, Dai Hong Phat Shaft Coupling is proud to be a trusted partner of hundreds of domestic and foreign enterprises.
Let us accompany your sustainable development!

DAI HONG PHAT TECHNICAL PRODUCTION TRADING SERVICES CO., LTD
– Ho Chi Minh City Office: 22 Street 11, Khang Dien Residential Area, Duong Dinh Hoi Street, Phuoc Long Ward, City. HCM
– Hanoi Office: No. 14-15A, 7th Floor, Charmvit Building, No. 117 Tran Duy Hung, Thanh Xuan Ward, Hanoi City.
– Tel HCM: +84.28.22536631 – 22536632 – 66818587 | | Fax: 028.22536632
– Hotline: +84906.955.057 | – Email: info@dhp-corp.com.vn
– Website: https://en.daihongphat.asia/ – https://khopnoitruc.com/ – https://ringfeder.com.vn/