Step 1: Determine Torque and Service Factor
This is the most critical step to ensure the coupling can handle the load without failing.

• Calculate Required Torque: Use the formula: Torque (N-m) = [Power (kW) × 9550] / Speed (RPM).

• Apply a Service Factor: Multiply the calculated torque by a service factor based on the driven equipment. For example:

  • Centrifugal Pumps: 1.5 – 2.0

  • Conveyors: 1.5 – 2.0

  • Compressors: 2.0 – 3.0

• Match to XL Size: Select an XL coupling size (e.g., XL-095, XL-140) where the coupling’s Rated Torque exceeds your torque (with service factor). The GR spider’s torque capacity is specified in the manufacturer’s catalog.

Step 2: Define Shaft and Speed Requirements

• Shaft Diameters & Keyways: Measure the exact diameters of both shafts. XL couplings have standardized bore sizes. Ensure your shafts fit the available range or opt for custom boring.

• Maximum RPM: Confirm your system’s maximum operating speed is below the coupling’s maximum speed rating. Exceeding this limit can be dangerous.

Step 3: Assess Misalignment and Environmental Conditions

• Misalignment Capacity: XL couplings with GR spiders accommodate moderate angular and parallel misalignment. Check the manufacturer’s chart for specific limits for your chosen size.

• Environmental Suitability of GR (NBR) Spider:

  • Temperature Range: Standard GR spiders perform well between approximately -40°C to 100°C.

  • Resistance: Excellent resistance to oils, fuels, and abrasion. It is not recommended for ozone, weathering, or strong polar solvents.

Step 4: Select the Correct Spider Hardness
The GR spider is available in different hardness levels (Shore A) to fine-tune performance:

• Standard Hardness (e.g., 92A): Ideal for general-purpose applications with standard vibration levels.

• Softer Spider (e.g., 80A): Provides superior vibration damping and shock absorption for high-impact equipment.

• Harder Spider (e.g., 95A): Offers higher torsional stiffness and is better for applications requiring less angular deflection.

Summary: Why Choose an XL Coupling with a GR Spider?

Choose this combination if your application requires:

• Excellent vibration damping and shock absorption.

• Reliable performance in environments with oil presence.

• Electrical insulation between connected shafts.

• A maintenance-free and lubrication-free solution.

• A cost-effective solution for pumps, compressors, fans, and conveyors.

Final Recommendation: Always consult the manufacturer’s technical catalog for precise sizing tables and service factors. For challenging applications, provide your parameters (Torque, RPM, Shaft Sizes, Environment) to your supplier for a verified and guaranteed selection.