GS 28 - 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]
28	160	180	200	38	–	–	–	65	30	90	35	–	20	15	2.5	4.0	M 8	15	10

The GS 28 Coupling (Size 28) is a high-capacity, zero-backlash flexible coupling engineered for heavy-duty servo drives and precision automation systems. With an outer diameter of 65mm, the GS 28 is a significant step up in performance from the GS 24, offering nominal torque capacities of up to 160 Nm (with a 98 ShA spider).

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Key Specifications (Model GS 24)

The GS 28 is the preferred size for larger servo motors and demanding linear actuators. Below are the standard technical specifications:

Parameter	Value
Coupling Size	GS 28 (Size 28)
Nominal Torque	95 Nm (92 ShA Yellow) / 160 Nm (98 ShA Red) / 200 Nm (64 ShD Green)
Max. Torque (Peak)	190 Nm to 400 Nm (approx. 2x Nominal)
Max. Rotational Speed	Up to 11,000 RPM (Standard Hubs)
Bore Range	10 mm to 38 mm (Standard)
Outer Diameter	65 mm
Hub Material	High-Strength Aluminum (Steel options often available)

How It Works

The GS 28 utilizes a proven pre-tensioned design to deliver high torque without backlash:

Backlash Elimination: The elastomeric spider is dimensionally larger than the gap between the coupling jaws. During assembly, the spider is compressed into the jaws under high pressure, creating a tight interference fit that removes all clearance.
High-Torque Transmission: The concave jaw profile maximizes the contact area with the spider teeth. This allows the GS 28 to handle heavy torque loads and shock spikes without deformation or loss of accuracy.
Vibration Damping: The internal spider acts as a buffer between the motor and the load. It absorbs torsional vibrations and dampens resonance, which is critical for protecting ball screws and gearboxes in high-speed machining.

Benefits of GS 28 Couplings

High Power Density: Capable of transmitting 160 Nm of torque in a compact 65mm diameter, providing the strength needed for heavy axis drives.
Precision Accuracy: The zero-backlash connection ensures high repeatability and positioning accuracy, essential for modern CNC machining and printing applications.
Electrical Isolation: The polyurethane spider electrically isolates the driving and driven shafts, preventing ground loops and protecting sensitive feedback devices (encoders).
Blind Assembly: The axial "plug-in" design allows for easy installation in tight spaces, such as inside bell housings or motor mounts.
Low Inertia: The use of aluminum hubs minimizes rotational mass, allowing for high dynamic performance and rapid acceleration/deceleration cycles.

Typical Applications

The GS 28 is widely used in heavy-duty precision industries:

CNC Machining Centers: Main spindle drives and heavy feed axes (X, Y, Z).
Printing Machinery: Precision roller drives and tension control systems.
Packaging Systems: Heavy-duty cartoners and palletizing robots.
Linear Actuators: Coupling large servo motors to precision ball screws and belt drives.
Material Handling: Automated storage and retrieval systems (ASRS) and conveyors.

Summary

The GS 28 Backlash-Free Coupling is the robust solution for engineers requiring high torque and precision. With a capacity of up to 160 Nm and zero backlash, it offers the stiffness and reliability needed for heavy-duty automation and machining. Its vibration-damping properties and maintenance-free design make it a critical component for ensuring long-term performance in demanding industrial environments.