The Lovejoy LM torsional couplings are made especially for diesel engine drives. In particular, the LM couplings are highly elastic torsionally, allowing the engine to drive a relatively small inertia load safely free from damaging torsional resonance over a wide speed range from low idle RPM to full engine speed. They accomplish this task by shifting the critical speeds far enough below the idle speed to allow full use of the entire working speed range of the engine without limitation. In essence, these sophisticated couplings effect an attenuated level of stress throughout the whole drive train by reducing vibratory torque to a very low level.


How they work
A compact, disc-shaped elastomeric element lies at the heart of the LM coupling that gives it its high torsional elasticity. This element has molded cogs, or teeth, around its outside diameter. These cogs make a backlash-free engagement with internal cogs on an aluminum ring which drives it from the engine flywheel. This arrangement pre-loads the elastomer to increase its damping and load carrying capacity, and gives the coupling the ability to slip together and "blind assemble" inside the engine's flywheel housing. It also gives the coupling some torque limiting ability to further protect the drive train, as the cogs are able to slip position during rare transient torque spikes (5 to 6 times rated torque) without damage to the coupling. If these spikes were to occur frequently, only harmless bits of rubber would shed from the coupling causing no further damage. The shape of the elastomeric element distributes operating stresses equally over its working section, allowing for a large angle of twist (6 to 12° at nominal torque load depending on size) while minimizing stress. This feature places the LM coupling amongst the highest torsional elasticities of all couplings available on the market. At the thick center portion near the hub, as well as at the cogs, stresses are further reduced to a very low level, providing a very reliable and robust drive. We bond a steel ring to the center of the elastomeric element that assembles to a steel hub. The center of this hub is machined to fit the customer's driven shaft and is clamped solidly to the shaft at assembly by a tapered split hub, set screws or the L-Loc clamping system.

Range of sizes:
LM couplings come in 8 different sizes covering a range of nominal torques from 250 to 3800 Nm. This wide range of sizes make these couplings capable of handling applications driven from small single-cylinder engines on up to large multi-cylinder engines producing in excess of 600 kW.

Materials:
Elastomeric element: Temperature-resistant natural rubber available in a variety of Shore hardnesses to suite individual application requirements. Our natural rubber is good for -45 °C to +90 °C. For unusually high ambient temperatures, especially in non-ventilated flywheel housings, we recommend using our special silicone version, rated for -45 °C to +120 °C.
Outer ring: High-grade cast aluminum alloy.
Inner hub: Steel with minimum tensile strength of 600 N/mm2