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Item # 68514476429, LF Series Flange Hub with Keyway - Inch (Imperial) Bores

    The LF Series coupling is designed with a unique and highly versatile elastomeric element. These can be easily integrated into a variety of coupling configurations to meet several application needs. LF Style elements are available in a variety of materials to match the necessary coupling dampening characteristics for tuning the systems critical speed away from the application operating speed.

    The element can be connected axially to a flywheel adapter plate or flanged hub and radially to a cylindrical center hub using the appropriate bolts. Axial bolt styles include either socket head bolts with a special dry adhesive, or S-Style bolts, which are similar to dowel pins (seen picture below). The radial bolts are used to connect the element to the cylindrical hub. This unique design is remarkably simple, highly effective and gives the LF torsional coupling unmatched performance capabilities. The coupling selection should be verified with a Torsional Vibration Analysis (TVA) of the system.

Specifications  · Dimensional Data  · Performance Data  · Torsional Element Specifications  · Features  · Notes



LF4 HUB FLNG 3/4 *1/4X1/8KW



Coupling Size



2.80 lb





Bore Type

Finished Bore

Dimensional Data

Bore Size 

3/4 in

Thread (Dimension T)


Keyway Size (W x D)

1/4 x 1/8 in

Hub Diameter

1.770 in

Length thru Bore

1.180 in

Min. Bore (Dimensions ID1/ID2)

0.630 in

Max. Bore (Dimensions ID1/ID2)

1.75 in

Dimension FD

2.560 in

Dimension FOD

3.940 in

Cubic inches

18.31785 in³

Performance Data


-40 to 194 ºF

Operating Temperature Range

-40 to 194 ºF

Nominal Torque

440.00 in·lb

Max. Torque

1100.00 in·lb

Allowable Continuous Vibratory Torque

180.00 in·lb

Max. Speed

7000.00 rpm

Max. Angular Misalignment

3.00 º

Max. Parallel Misalignment

0.060 in

Wind-Up Angle at Nominal Torque

5.00 º

Wind-Up Angle at Max. Torque

12.00 º

Dynamic Torsional Stiffness

7500.00 in·lb/rad

Static Angular Stiffness

21.30 in·lb/deg

Static Axial Stiffness

430.00 lb/in

Static Radial Stiffness

2860.00 lb/in

Shore Hardness


Torsional Element Specifications
    There are two different rubber element materials available, High Temperature Rubber (HTR) and Neoprene (CR). Both elements are torsionally soft and are placed into compression during assembly. Rubber under compression can carry up to 5 times the amount of torque as non-compressed elements. The elements effectively accommodate shock, misalignment, and vibration plus minimize harmful radial and axial forces on the connected equipment. Neoprene (CR) is used in environments that are hostile to High Temperature Rubber (HTR).
    Available Durometer Hardness:
  • 50, 60 (Shore A scale)
    Operating Temperature Range:
  • HTR: -40° to 194° F
  • CR: -40° to 175° F
    Maximum Angular Misalignment:
  • Up to 3°



  • Wide range of standard designs and materials
  • Application versatility
  • Shaft to shaft or flywheel to shaft designs
  • Designed to accommodate substantial shock loads, vibration, and misalignment
  • Low moment of inertia
  • Electrically insulating
  • No lubrication, maintenance free
  • Unique air-flow cooling design
  • Different element stiffness values allow for torsional tuning of applications with diesel engines
  • Economic design allows for cost effective solutions for torsional applications
  • Proven L-LOC spline-clamping hub virtually eliminates spline shaft profile wear and “fretting”
  • Oil, heat, and corrosion resistant elements (Hytrel®, Zytel®)
  • When used with S-bolts, the coupling can accommodate some end float
  • S-bolts accommodate applications requiring “blind” assembly
  • Model 6 unique spacer designs span gaps between equipment in excess of the normal equipment separation
  • Model 6 design available with bearings for high speeds and large amounts of equipment separation



  • For Hytrel, dynamic torsional stiffness values are non-linear with respect to torque. Value given is for 100% of nominal torque.
  • Angular and parallel misalignment values are dependent on speed, and for rubber elements, should be adjusted according to figure 4. Hytrel® elements are only for applications where the driven component is piloted to the driver for SAE and DIN established alignments (i.e. Hydraulic pump flange-mounted to engine flywheel housing).
  • Hytrel® elements are only for applications where the driven component is piloted to the driver for essentially perfect alignment (hydraulic pump flange-mounted to engine housing).


Torsional Products Catalog
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LF Installation Instructions - Hytrel
(PDF, 0KB)

LF Installation Instructions - Model 6
(PDF, 0KB)

LF Installation Instructions - Models 1, 2, & 3
(PDF, 0KB)