GS 9 - AXIS GS Couplings

GS standard types - For size 5 to 38 hub material aluminium/for size 42 to 90 hub material steel
Size	Spider GS ¹⁾ torque T_KN [Nm]			D_max. for hub type			Dimensions [mm]										Setscrew DIN EN ISO 4029
Size	98 ShA	57 ShD	64 ShD	1.0	1.1	1.2	DN	DH	DI1	L	L1, L2	M, N	E	B1	S	A	G	T	TA [Nm]
9	5.0	–	6	10	11	11	–	20	7.2	30	10	–	10	8	1.0	1.5	M 4	5.0	1.5

The GS 9 Coupling (Size 09) is a high-performance, backlash-free flexible shaft coupling designed for servo drives and precision positioning systems. With an outer diameter of 20mm, it sits comfortably in the "small-to-medium" miniature range, offering significantly higher torque capacity than the GS 5 or GS 7 while retaining a compact, low-inertia profile.

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Key Specifications (Model GS 9)

The GS 9 is a versatile size for automation, balancing torque density with a small footprint. Below are the standard technical specifications:

Parameter	Value
Coupling Size	GS 9 (Size 09)
Nominal Torque	3.0 Nm (92 ShA) / 5.0 Nm (98 ShA)
Max. Torque (Peak)	6.0 Nm to 10.0 Nm (approx. 2x Nominal)
Bore Range	4 mm to 11 mm (Standard) / 12 mm (Max)
Outer Diameter	20 mm
Hub Material	High-Strength Aluminum

How It Works

The GS 9 achieves its zero-backlash performance through a pre-tensioned design:

Interlocking Jaws: The aluminum hubs feature precision-machined concave jaws that interlock with the involute teeth of the elastomer spider.
Pre-Stress Fit: The spider is dimensioned slightly larger than the space between the hub jaws. Upon assembly, the spider is compressed, creating a tight, pre-loaded fit that eliminates all mechanical play.
Torque Transmission: Under load, the pre-stress ensures that the system remains backlash-free even during reversing loads, while the curved jaw profile distributes pressure evenly to handle high torque spikes.

Benefits of GS 9 Couplings

High Torque Density: Despite its small 20mm diameter, it can transmit up to 5.0 Nm of nominal torque (with a 98 ShA spider), capable of driving small CNC axes and robotic joints.
Vibration Damping: The elastomeric spider acts as a shock absorber, smoothing out torque ripples from stepper motors and reducing resonance in the drive train.
Misalignment Compensation: It accommodates axial, angular, and parallel shaft misalignment, protecting bearings from excessive radial loads caused by thermal expansion or mounting errors.
Electrical Isolation: The polyurethane spider electrically isolates the driving and driven shafts, preventing ground currents from interfering with sensitive encoders or controllers.
Easy Assembly: The axial "plug-in" design allows for blind assembly, making it easy to install in confined spaces inside machinery.

Typical Applications

The GS 9 is widely used in automation and precision manufacturing:

Linear Actuators: Connecting servo motors to ball screws or belt drives.
Robotics: Joint actuators in small industrial robots and grippers.
Medical Devices: Precision pumps, imaging equipment, and surgical robots.
Optical Systems: Positioning drives for lenses and mirrors.
Machine Tools: Feed drives in miniature milling and turning machines.

Summary

The GS 9 Backlash-Free Coupling is the go-to component for engineers requiring a reliable, high-torque connection in a compact 20mm package. With a nominal capacity of up to 5.0 Nm and the ability to eliminate backlash entirely, it ensures the precision and repeatability required for modern motion control systems. Its maintenance-free, electrically isolating design makes it a "fit and forget" solution for high-performance machinery.