LOVEJOY

Lovejoy L-type jaw couplings are the standard inch-series couplings, with sizes such as L050, L070, L075, L090, L095, L099, L100, L150, L190, L225, and larger. AL-type couplings are the metric series, with sizes like AL099 and AL100. The two series have different bore and keyway dimensions, but both use the same jaw coupling principle: two hubs with intermeshing jaws and an elastomeric spider. Spiders are not interchangeable between L and AL sizes because the outside diameters and jaw profiles differ. When selecting, match the coupling size to the shaft diameters and required torque. Lovejoy provides dimensional data and torque ratings for each size. 3G Electric stocks both L and AL series hubs and spiders.

Lovejoy offers spiders in several materials, including Buna N rubber, Hytrel, and urethane. Buna N rubber is the standard material, providing good vibration damping and misalignment capacity, with a temperature range of approximately -40°F to 212°F (-40°C to 100°C). Hytrel spiders offer higher torque capacity and greater resistance to chemicals and oils, but with reduced misalignment capability. Urethane spiders provide high torque capacity and good wear resistance. The durometer of the spider affects stiffness: a higher durometer (e.g., 80A, 95A) transmits more torque but offers less damping. The spider material must be compatible with the operating environment and the required torque. Lovejoy publishes torque ratings for each spider material and size. 3G Electric supplies spiders in various materials and durometers.

Selection involves determining the required torque, shaft diameters, misalignment, and environmental conditions. First, calculate the torque based on the driver power and speed, then apply a service factor for the application. Choose a coupling size with a torque rating exceeding the calculated torque. Next, select hubs with bores matching the shafts, available in inch or metric sizes, with or without keyways. Consider the spider material for torque and damping. Check the maximum misalignment allowed for the coupling size and spider. Also verify the maximum speed and temperature limits. Lovejoy provides selection guides and dimensional drawings. For assistance, 3G Electric can help interpret specifications and identify the appropriate part numbers.

Temperature limits depend on the spider material. Buna N rubber spiders are typically rated from -40°F to 212°F (-40°C to 100°C). Hytrel spiders can operate from -60°F to 250°F (-51°C to 121°C). Urethane spiders generally range from -30°F to 160°F (-34°C to 71°C). These are guidelines; actual limits may vary with speed and load. Speed limits are determined by the coupling size and balance. Standard couplings are suitable for speeds up to 5,000 rpm, but larger sizes may have lower limits. For high-speed applications, balanced couplings are available. Exceeding temperature or speed limits can cause premature spider failure. Always consult Lovejoy's technical data for specific ratings. 3G Electric can provide speed and temperature ratings for the couplings it supplies.

Some Lovejoy jaw coupling hubs are designed to be fail-safe, meaning that if the elastomeric spider fails, the coupling can still transmit torque through the intermeshing jaws. This is achieved by the jaws of the two hubs engaging directly, providing a mechanical backup. However, this condition is intended for emergency operation only, as it may cause vibration and noise, and can damage the hubs if operated for extended periods. Not all Lovejoy couplings are fail-safe; it depends on the hub design. For example, the L050 hub (SKU 864TL9) is listed as fail-safe. When specifying a coupling, consider whether fail-safe operation is required for your application. 3G Electric can identify fail-safe options within the Lovejoy line.

Lovejoy jaw couplings are manufactured to various standards, including ANSI B92.1A for keyways, ANSI/AGMA 9002-B04 for shaft fits, ANSI/AGMA 9112-A04 for coupling dimensions, and DIN 5480 for metric splines. These standards ensure dimensional interchangeability and proper fit with shafts and other components. Compliance with these standards means that Lovejoy couplings can be used as replacements for other couplings that meet the same standards. However, always verify the specific dimensions and tolerances for your application. Lovejoy provides detailed specifications for each coupling size. 3G Electric supplies Lovejoy couplings that meet these standards, and can provide documentation upon request.