| Coupling Size | Torque Nm | Max. Speed (RPM) | Bore Dia MIN | Bore Dia MAX | QTY N | A | B | C | D | E | F |
|---|---|---|---|---|---|---|---|---|---|---|---|
| FBC 4 | 831 | 3000 | 20 | 70 | 4 | 191 | 125 | 60 | 5 | 105 | 114 |
The Flexible Bolt Coupling FBC 4 is a heavy-duty industrial coupling engineered for high-torque applications. It features a significant increase in physical size and torque capacity over the FBC 3, making it suitable for large-scale machinery. Despite its increased strength, it maintains the four-pin configuration, allowing for easier maintenance while handling up to 831 Nm of torque.
Nominal Torque Capacity: 831 Nm
Maximum Speed: 3,000 RPM
Bore Diameter Range: 20 mm – 70 mm
Quantity of Pins (N): 4
Outer Diameter (A): 191 mm
Overall Length (B): 125 mm
The FBC 4 functions as a flexible power transmitter that connects two shafts via four large-diameter pins. Each pin is fitted with a specialized elastomeric bush that sits within the driven flange.
As the driving shaft rotates, torque is transferred through the compression of these flexible bushes. This design specifically targets the elimination of metal-to-metal contact between the flanges, which allows the coupling to:
Absorb Shock: Cushion the drive system against sudden load spikes.
Compensate for Misalignment: Allow for the inevitable axial, parallel, and angular deviations that occur during heavy industrial operations.
Insulate Vibration: Prevent high-frequency motor vibrations from reaching sensitive driven equipment.
Large Bore Capacity: Supports shaft diameters up to 70 mm, making it compatible with large-frame electric motors and heavy-duty gearbox shafts.
Simplified Maintenance: The 4-pin layout (N=4) makes it faster to inspect and replace the flexible elements compared to high-pin-count models.
Robust Housing: With an outer diameter (A) of 191 mm, the coupling provides superior mechanical leverage and heat dissipation.
Zero Lubrication: Completely maintenance-free regarding lubricants, reducing environmental impact and housekeeping requirements.
Safety Gap: Features a 5 mm axial gap (Dimension D) that protects against "end-float" damage to motor and machine bearings.
Heavy Duty Pumps: Ideal for large-volume fluid transport in wastewater, mining, and oil & gas.
Industrial Shredders & Grinders: Used where high torque and frequent shock loads are expected.
Main Conveyor Drives: Powering heavy-duty conveyor systems in bulk material handling.
Mining Equipment: Suitable for slurry pumps and smaller secondary crushers.
Large HVAC Units: Used in high-capacity industrial chillers and massive air-handling units.
Speed Threshold: The maximum operational speed is 3,000 RPM. This is perfectly suited for standard 4-pole and 6-pole motors, but must not be used with high-speed 2-pole motors exceeding this limit.
Hub Engagement (Dimension C): The 60 mm hub depth requires a substantial shaft length to ensure full keyway engagement for maximum safety.
Torque Safety Factors: Given the 831 Nm rating, users should calculate the total system torque (including starting peaks) to ensure the coupling is correctly sized for long-term bush life.
Clearance: Ensure the 191 mm outer diameter (Dimension A) has sufficient clearance within the machine guards or housing.
The Flexible Bolt Coupling FBC 4 is a robust solution for transmitting high torque in demanding environments. By supporting bores up to 70 mm and offering a torque capacity of 831 Nm, it bridges the gap between general industrial use and heavy-duty process machinery. Its 4-pin design ensures it remains easy to maintain while providing the "mechanical fuse" protection necessary for expensive downstream equipment.
