LM Series Torsional Coupling

The LM Series torsional couplings are designed specifically for diesel engine driven equipment. The LM couplings are highly torsionally compliant, allowing the engine to drive a relatively small inertia load safely from damaging torsional resonance over a wide speed range from low idle RPM to full engine speed. This task is accomplished by shifting the critical speeds far enough below the idle speed allowing full use of the entire working speed range of the engine with very few limitations. These engineered couplings affect an attenuated level of stress throughout the whole drive train by reducing vibratory torque to a very low level. The coupling selection should be verified with a Torsional Vibration Analysis of the system.

  • Designed for mounting on standard SAE J620 flywheels
  • Available in high temp rubber (HTR), EPDM, or Silicone
  • Nominal torque: up to 33,600 in-lb (3800 Nm)
LM Series Torsional Coupling


LM Series Torsional Coupling Additional Resources


  • Elastomeric Element
    • Temperature-resistant natural rubber available in a variety of Shore A scale hardness
    • Silicone element available for high ambient temperatures
    • EPDM available for chemical resistant
  • Outer Ring
    • High grade cast aluminum alloy
  • Inner Hub
    • Steel with minimum tensile strength of 85,000 psi (600 N/mm²)
    • Available in bore with keyway and spline connections
    • Taper-Loc spline hubs available
    • Splines with L-LOC available

Range of Sizes

  • 8 sizes ranging from nominal torques of 2,210 to 33,600 in-lb (250 to 3800 Nm)
  • SAE J620 Flywheel sizes available from 6 through 18
  • 3 coupling design types.

Typical Applications

  • Splitter-gear multiple pump drives
  • Generator sets (2-bearing)
  • Locomotives
  • Hydraulic pumps
  • Centrifugal pumps Compressors

Type SB (Sizes 240 to 2400)

The driven inner hub consists of two pieces: the vulcanized steel ring and the inner tapered hub. These two parts are bolted together and the torque is transmitted by the friction force created by the axial bolts, drawing the tapered hub into the mating taper in the element.

This is a long tapered fit, but can easily disassembled if the coupling has to be removed. The vulcanized steel ring creates a very high inward pressure acting on the inner driven tapered hub. To utilize this pressure, the driven hub is slotted in an axial direction. This compresses the driven hub and driven shaft. This clamping effect can be used equally well on cylindrical shafts with keys or splined shafts.

Type SC (Sizes 2800 to 3500)

An inner ring made of spheroidal cast iron is vulcanized into the elastomeric element. This flange is bolted to the inner tapered hub. Depending upon the arrangement of the elastomeric element, two different lengths are possible utilizing the same components.

Standard Configuration: SCA
Reversed Element: SCB
(extended mounting length)

Types SBE and SCE Special Radial Assembly / Disassembly Types (All Sizes)
(Drop-Out Types)

The elastomeric element can be changed quickly and easily without disturbing the coupling shaft, provided the flywheel housing does not protrude too much. These versions can be particularly advantageous on larger sizes, especially if the hub is interference fit.

Special Types
In addition to the standard types described here, many special types have been developed. Please contact Lovejoy Technical Support for more information.

Please download the Lovejoy Torsional Coupling Catalog for performance and dimensional data.

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