FMM Type Mill Universal Hubs - Rough Stock Bore

The FMM Type coupling consists of one universal  hub (FMM Mill Type), one standard F Type flex hub, two standard F Type flex sleeves, and one accessory kit. This coupling is supplied with exposed bolts as standard, with shrouded bolts are available upon request through size 5.5.

The FMM Type Mill Universal hub accommodates AISE Mill Motor frame sizes (with the two sleeves and second hub being standard F Type).

Unit of Measure




Hub Style

N/A Exposed Bolt


N/A Gear Coupling Hubs

Hub Material

N/A AISI 1045


N/A Unbored


N/A Metallic

Bore Type

N/A Rough Stock Bore

Coupling Type

N/A Gear


N/A 7.60 lb

Complete Coupling Weight

N/A 24.00 lb

Dimensional Data

Bore Size

N/A 0.690 in18.00 mm

Max. Bore (Dimensions ID1/ID2)

N/A 2.125 in56 mm


N/A 1 1/2

Set Screw Style Coupling Size (Dimension T)

N/A No Setscrew


N/A 4.500 in

Overall Length

N/A 6.560 in166.62 mm

Dimension D

N/A 3.970 in100.84 mm

Dimension FD

N/A 6.00 in152.40 mm

Dimension HD

N/A 3.000 in76.20 mm

Distance between Shaft Ends (Dimension BSE)

N/A 0.130 in3.30 mm

Length Through Bore of Universal Hub (LTB1)

N/A 4.500 in114.30 mm

Cubic inches

N/A 40.50000 in³

Performance Data

Nominal Torque

N/A 18900 in·lb2140 N·m

Max. Speed (Unbalanced)

N/A 5500 rpm

Max. Speed (Balanced)

N/A 8250.00 rpm

Parallel Misalignment

N/A 0.060 in

Max. Angular Misalignment

N/A 1.50º per Gear Mesh



  • Patented Vari-Crown® tooth form for long life
  • Standard 20° pressure angle
  • Heat treated bolts for greater strength
  • Corrosion resistant bolts and nuts for ease of maintenance
  • Provides parallel, angular misalignment and end float
  • Flex Half coupling interchangeable with industry standards
  • Long Universal Hub supplied to customer specifications with straight or tapered bores



  • LTB1 Dimensions are the maximum lengths of Universal Hubs kept in stock and altered to customer specifications. Longer length hubs are made to order.
  • Exposed Bolt Design is standard.
  • Shrouded Bolt Design available upon request for sizes 1 through 5.5.
  • Puller Holes are standard on sizes 4 through 6.
  • Puller Holes are available for sizes 1 through 3.5 at an additional charge.
  • Interference bores with no set screws are standard unless otherwise specified.
  • Inch bore and keyway tolerances conform to ANSI / AGMA 9002-B04.
  • For metric bore and keyway tolerances, consult Lovejoy Engineering Section.