Torsional Couplings stop vibration, absorb loads.

Press Release Summary:



LF, LK and LM solve torsional vibration problems common to internal combustion engine driven applications such as pumps, compressors and gen-sets. They absorb shock loads, accommodate misalignment, and handle shifting critical speeds safely above and below normal rpm operating ranges. All are non-lubricated and maintenance-free. Options include pump mounting plates and cast aluminum pump-mounting housings for engines lacking SAE flywheel housing.



Original Press Release:


Lovejoy Begins Worldwide Marketing Of Torsional Couplings For Engine-Driven Systems, Offers Range Of Solutions For Torsional Vibration Problems


DOWNERS GROVE (IL/USA), FEB. 1, 2002 -- A broad line of shaft- or flywheel-mounted couplings being introduced worldwide by Lovejoy, Inc., comprising the LF, LK and LM Families, solves virtually all types of torsional vibration problems common to internal combustion engine driven applications such as pumps, compressors and gen-sets. These three basic designs, with a variety of configurations, offer alternatives for absorbing shock loads, accommodating misalignment and/or shifting critical speeds safely above/below normal RPM operating ranges. All are non-lubricated, maintenance-free designs featuring easy assembly and rugged construction.

Lovejoy's LF Family offers the group's most versatile coupling design, built around a donut-shaped elastomeric element alternately bolted to a cylindrical center shaft hub and a flange-type shaft hub. The alternating radial and axial mounting bolts assure "failsafe" service that continues transmitting torque in the unlikely event of elastomer failure. Fifteen sizes accommodate nominal torque up to 5,000 Nm (12,500 Nm max), and continuous vibratory torque up to 2,000 Nm. Elastomers are offered in a choice of natural rubber or Neoprene -- both in four durometer hardness ratings for a wide range of torsional vibration requirements -- plus Hytrel(R) for greater torsional stiffness and temperature tolerance, and Zytel(R) for ultimate torsional stiffness, temperature tolerance and chemical resistance.

Elastomer donuts from the LF Family are available separately for mounting on user-designed hubs, or with center hub only for mounting directly to engine flywheels, pulleys, brake discs, friction clutches, U-Joints or gears. Additional models are provided with flywheel mounting plates in all standard SAE flywheel sizes, and shaft hubs in a variety of ANSI (SAE), DIN and JIS splined bores, as well as straight or tapered bores. Splined hubs feature the L-Loc design, which applies clamping force evenly around the entire shaft profile to eliminate spline distortion and fretting.

A special thin-profile LF Family model serves close engine-housing/pump applications, with a disc-shaped Hytrel element pilot-mounted to a cast alloy SAE flywheel adapter plate machined to SAE J620 specifications. In addition, floating-shaft models are available in buyer-specified lengths, with special corrosion- and heat-resistant materials, and special designs to allow free endplay or accommodate long spans.

Lovejoy LK Family flywheel couplings offer a simple, robust two-piece unit with nearly rigid torsional stiffness. Intended for diesel, gasoline or natural gas engines in the low- to mid-power ranges, LK couplings raise critical speeds well above the operating RPM of low-inertia equipment such as hydraulic pumps and hydrostatic drives. Five sizes accommodate nominal torque up to 2,400 Nm (6000 Nm max).

The LK design features a molded Polyamid flange strengthened with glass fiber to produce a high-impact material that withstands temperatures of -40 to +3000 deg F (-40 to 1500 deg C). Molded into the flange is a socket shaped to receive a "hubstar" consisting of a shaft-mounting hub fitted with four, six or eight radial dogs. The coupling installs in less time and at lower cost than conventional diesel/pump flywheel couplings by bolting the coupling's flange to the engine flywheel, mounting the hubstar on the pump shaft, advancing the pump to seat the hubstar into the flange socket, then bolting the pump to the pump mounting plate or housing.

Standard LK flanges are one-piece units sized to fit standard flywheels ranging from SAE 6.5 through 14 using SAE J620 mounting measurements, as well as to fit metric flywheels. For other non-standard flywheels, a special two-piece mounting combines a universal flange with a steel adaptor. Hubstars, using the L-Loc system, can be mounted anywhere along the splined shaft at the ideal axial location to mate properly with the flange socket.

Although very stiff radially as well as torsionally, LK Family flanges are able to compensate for small radial and angular misalignments normal with flange-mounted drives. Hubstar dogs have slight crowns along their lateral flanks to avoid edge pressure at angular misalignment.

Lovejoy LM Family flywheel couplings are made expressly for diesel engines driving relatively small inertia loads such as splitter-gear multiple pump drives, two-bearing generator sets, centrifugal pumps, compressors and marine propulsion, designed to shift critical speeds low enough to avoid torsional resonance across the entire operating range from low idle to full RPM. Eight sizes with nominal torque ratings from 250 to 3800 Nm cover applications ranging from small single-cylinder to large multi-cylinder engines.

Very soft torsionally, the LM coupling features a disc-shaped elastomeric element with cogs or teeth molded around its perimeter. These cogs mate in a no-backlash fit with internal cogs cast into an aluminum ring mounted on the engine flywheel. Elastomeric elements are offered in natural rubber with a variety of Shore hardness ratings and temperature tolerance of -450 deg C to +90 deg C, or special silicone rubber that extends temperature tolerance up to +1200 deg C. The element's shape is designed to allow a large angle of twist (6 to 12 deg), while reducing stress at its thicker portions around the center and around the perimeter at the cogs.

A steel ring bonded into the center of the elastomeric disc assembles to a steel hub that is machined to fit the user's keyed or splined driven shaft, and mounted by set screws, tapered split hub or the L-Loc clamping system. A special radial assembly/disassembly (drop-out) type LM coupling allows the elastomeric element to be changed quickly and easily without disturbing the coupling shaft.

The Lovejoy torsional coupling line also includes pump mounting plates, plus light-weight cast aluminum pump-mounting housings for engines lacking an SAE flywheel housing, in styles designed to fit a variety of Cummins, Ford, Kubota, Deutz, GM and Perkins engines.

Founded in 1900, Lovejoy is an international leader in flexible coupling design and development, and the creator of the industry standard Jaw style coupling. Through the breadth of its product line, which includes Curved Jaw, S-Flex, Gear, Torsional, and Disc style couplings, Lovejoy has built a reputation as a resource for flexible couplings that can serve applications of all types and sizes. Lovejoy also manufactures a complete line of variable speed pulleys and universal joints.

Lovejoy products are available worldwide from hundreds of power transmission distributors in North America as well as 45 other countries. Lovejoy supports their efforts from a network of regional sales offices and warehouses, and a large engineering, marketing, and customer service staff in Canada, Europe, and the USA. Lovejoy, Inc., is certified under the ISO-9001 International Standards for Quality Management.

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