LF Series Torsional Coupling

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. 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. (Information required to perform a TVA can be found inside the downloadable catalog.)

  • Family of couplings designed specifically to address problematic torsional vibration
  • Wide variety of solutions for diesel engine driven equipment
  • Excellent engineering staff on hand; ready to help
LF Series Torsional Coupling

LF Series Torsional Coupling Additional Resources

Click here to access Lovejoy’s Digital Parts Catalog for the most popular LF Series components.

Please contact us if you are unable to find the part you are looking for or need a Torsional Vibration Analysis (TVA) of your system.

LF Series Feature Summary:

  • 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

Lovejoy’s LF product line supports both standard style elements (above left) and the S-Style elements (above right). The standard style elements bolt to the cylindrical (center) hub and the flywheel, flywheel adapter, or flange hub. The S-Style utilizes bolts which look like dowel pins and are designed for “blind” installations, where the axial bolts may not be accessible for tightening during the installation process. One application would be inside a bellhousing when all the components are assembled and the bolts cannot be reached. The S-Style bolts also accommodate a small amount of end float when necessary to prevent unnecessary axial stress on the element. When looking to replace elements, please note the difference in the axial holes. The standard elements have stepped holes to accommodate the cap screws (above left) which are used to mount the element. The S-Style elements have straight holes (above right) to accommodate the S-Style pins.

The focus of any coupling is the flexible elements, or the “working component”. The element must effectively absorb the shock loads, misalignment forces, and torsional vibrations, under a variety of environmental conditions. The following materials are used to accommodate the different conditions and environments where the couplings are used.

High Temperature Rubber (HTR)
There are two different rubber element materials available, High Temperature Rubber (HTR) and Neoprene (CR). Both elements are torsionally soft andare placed into compression during assembly. Rubber under compressioncan 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, 70, 75 (Shore A scale)
Operating Temperature Range: HTR: -40° to 194° F; CR: -40° to 175° F
Maximum Angular Misalignment: Up to 3°

Elements made of DuPont’s Hytrel® elastomer compound are torsionally much stiffer than natural rubber (20 times stiffer) and were developed for combustion engine / hydraulic pump applications. Hytrel® elements have 20% greater torque capacity as compared to rubber elements. The torsionally stiff Hytrel® element moves the harmful vibration resonance frequency above the operating RPM range. The element design also reduces harmful radial and axial reactionary forces.

Operating Temperature Range: -60° to 250° F
Maximum Angular Misalignment: 0.25°

Elements made of DuPont’s highly stressable Zytel® elastomeric compound have excellent chemical compatibility and corrosion resistance. The element composition is 3-times stiffer then Hytrel® elements. Zytel® elements exhibit less than 1° wind up at normal torque and zero backlash. Most suited for applications where heat, moisture, high torque / high speed, and corrosion resistance are critical factors in the coupling selection.

Operating Temperature Range: -40° to 300° F
Maximum Angular Misalignment: 1°

For other Torsional Couplings: see Torsional Couplings
Or, for other coupling types: see Coupling Preselection Guide