Flexible Shaft Couplings.

What are Flexible Shaft Couplings?

Flexible shaft couplings connect two shafts to transmit torque while taking up a degree of misalignment between them, whether angular, parallel or axial. Unlike a rigid coupling, a flexible coupling flexes just enough to absorb that misalignment and damp vibration, protecting bearings and keeping a drive running smoothly. They are a cornerstone of precision motion systems, from robotics and semiconductor equipment to medical devices and test rigs, wherever a motor shaft has to drive an encoder, lead screw or another shaft accurately.

How Flexible Shaft Couplings Work

A flexible shaft coupling grips both shaft ends and transfers torque between them, while a flexible element in its body accommodates the small misalignments that occur when components are fitted or settle over time. That flexibility is what separates a flexible coupling from a rigid one: it keeps torque flowing without forcing the shafts into perfect alignment, reducing the reaction loads that wear out bearings.

Accu's range achieves this in two different ways, which is the key choice for a designer. A beam coupling flexes through a helical slit machined into a single-piece body, giving a stiff, zero-backlash connection for accurate positioning. A high-gain coupling instead uses a moulded rubber core between its hubs, trading some stiffness for genuine vibration damping. In a printing or inspection system running at speed, for example, the right flexible motor coupling isolates vibration so tolerances stay tight; in an encoder feedback loop, a zero-backlash coupling keeps the position reading true.

Materials Flexible Shaft Couplings Are Made From

Accu's flexible shaft couplings use lightweight, corrosion-resistant materials, scoped to each range:

• Aluminium - Aerospace (Grade 7075): a high-strength aerospace aluminium used across the beam-coupling range, with a Surtec 650 passivated finish for corrosion resistance and low rotational inertia.
• Aluminium - (Grade 2017): the hub material on the high gain range, a strong, light aluminium in a natural finish.
• Rubber: the one-piece moulded core in the high gain range that transmits torque while damping vibration.

Sizes and Types of Flexible Shaft Couplings Available

Accu splits the family into two types, so you can match the coupling to what your drive needs. For zero-backlash positioning accuracy, choose our precise, zero-backlash beam couplings: single-piece helical-cut couplings in aerospace aluminium, in a compact micro range with bores from 1.5 to 5 mm and outside diameters from 6 to 10 mm, rated up to 70,000 RPM. For applications that need to absorb vibration rather than hold precise position, our high-gain couplings use a moulded rubber core in aluminium hubs and cover a larger envelope, with bores from 3 to 35 mm and outside diameters from 15 to 68 mm.

Across the family, that gives a size span from a 1.5 mm micro bore up to a 35 mm bore, so the range reaches from miniature encoder drives to larger motion assemblies.

FAQs

Q: What is the difference between a coupling and a flexible coupling?

A: A coupling joins two shafts to transmit torque; a flexible coupling does that while also accommodating angular, parallel or axial misalignment and absorbing some vibration, which makes it suited to applications where perfect alignment is difficult.

Q: How do you join two shafts together?

A: Most often with a coupling. A flexible shaft coupling fits over both shaft ends and grips them, transmitting torque between the shafts while tolerating slight misalignment.

Q: Which flexible shaft coupling should I choose, a beam or a high gain coupling?

A: Choose a beam coupling for zero-backlash positioning accuracy, such as encoder and small-servo feedback; choose a high-gain coupling when you need to damp vibration in a servo or stepper drive.

Q: Why use a flexible shaft coupling?

A: To transmit torque between two shafts while compensating for misalignment and absorbing vibration, which protects bearings and other components and keeps machinery running smoothly.

Q: What is the maximum rated speed of Accu's flexible shaft couplings?

A: The beam (Reli-a-Flex) range is rated up to 70,000 RPM, suiting high-speed precision drives.

Q: What is the difference between a rigid and a flexible coupling?

A: A rigid coupling locks two shafts solidly for perfectly aligned drives, while a flexible coupling accommodates misalignment and absorbs vibration, which is why it suits most real-world assemblies.

Bespoke Flexible Shaft Couplings Manufacture.

High precision, bespoke manufacture of Flexible Shaft Couplings to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.