GS 38 - 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]
38	325	365	405	45	–	–	–	80	38	114	45	–	24	18	3.0	4.0	M 8	15	10

The GS 38 Coupling (Size 38) is a heavy-duty, zero-backlash flexible coupling designed for high-torque servo drives and precision motion control. With an outer diameter of 80mm, the GS 38 is built to transmit substantial power, offering nominal torque capacities of up to 325 Nm (with a 98 ShA spider).

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Key Specifications (Model GS 38)

The GS 38 is a standard choice for large servo motors and heavy-duty actuators. Below are the standard technical specifications:

Parameter	Value
Coupling Size	GS 38 (Size 38)
Nominal Torque	190 Nm (92 ShA Yellow) / 325 Nm (98 ShA Red) / 405 Nm (64 ShD Green)
Max. Torque (Peak)	380 Nm to 810 Nm (approx. 2x Nominal)
Max. Rotational Speed	Up to 9,000 RPM (Standard Hubs)
Bore Range	12 mm to 45 mm (Standard)
Outer Diameter	80 mm
Hub Material	High-Strength Aluminum or Steel (depending on application)

How It Works

The GS 38 relies on a pre-tensioned elastomer design to ensure zero backlash under heavy loads:

Interference Fit: The elastomer spider is dimensionally slightly larger than the precision-machined hub jaws. When assembled under pressure, the spider is pre-stressed, removing all clearance and ensuring instant, rigid torque transfer.
High-Torque Transmission: The concave jaw profile maximizes the contact area with the spider teeth. This allows the GS 38 to transmit high torque loads while maintaining stiffness during rapid reversing cycles.
Vibration Damping: The internal spider acts as a shock absorber. In dynamic applications, it dampens torque spikes and vibrations, protecting the motor and driven components (like ball screws) from wear and resonance.

Benefits of GS 38 Couplings

High Power Capacity: Capable of transmitting over 300 Nm of nominal torque in an 80mm diameter, providing the strength needed for heavy-duty axis drives.
Precision Accuracy: The zero-backlash connection ensures high repeatability and positioning accuracy, which is critical for large-scale machining and printing operations.
Electrical Isolation: The non-conductive polyurethane spider electrically isolates the driving and driven shafts, protecting sensitive encoders and controllers from ground loops.
Plug-In Assembly: The axial "blind mate" design allows for easy installation and inspection, even in restricted spaces inside machine housings.
Low Inertia: When equipped with aluminum hubs, the GS 38 minimizes rotational mass, allowing for high dynamic performance and faster acceleration.

Typical Applications

The GS 38 is widely used in heavy industrial automation:

Large CNC Machines: Main spindle drives and heavy feed axes for milling and turning centers.
Robotics: Base actuators for heavy-payload industrial robots.
Presses & Forming: Servo-driven press feeds and metal forming machinery.
Packaging Lines: Heavy-duty palletizers and case packers.
Injection Molding: Electric screw drives and clamping units.

Summary

The GS 38 Backlash-Free Coupling is the robust solution for engineers requiring high torque and precision in heavy-duty applications. With a nominal capacity of up to 325 Nm and zero backlash, it provides the stiffness and reliability needed for demanding automation tasks. Its vibration-damping properties and maintenance-free design make it an essential component for high-performance industrial machinery.