Curved jaw couplings extend to motion control

Edited by the Engineeringtalk editorial team Apr 24, 2002

A new family of curved jaw flexible elastomeric couplings from Lovejoy offers a full selection of sizes, styles and mountings for virtually all types of industrial machinery.

A new family of curved jaw flexible elastomeric couplings from Lovejoy offers a full selection of sizes, styles and mountings for virtually all types of industrial machinery.

Lovejoy's CJ Series curved jaw couplings, which match the European standard, has been expanded to include larger sizes as well as the addition of a new GS Series designed for motion control applications.

These couplings accommodate applications driven either by electric motor or internal-combustion engine, with nominal torque ratings up to 35,000Nm (70,000Nm max).

Curved jaw couplings feature radial concave curvature in the jaw faces, which seats against an elastomeric insert moulded with matching radial and axial crowning.

This specially curved interface extends angular misalignment capability up to 1.3 degrees, parallel (radial) offset up to 0.6mm and axial float up to 4.6mm.

For broadest possible range of applications, Lovejoy's standard CJ Series curved jaw couplings now include a variety of close and extended spacer designs.

These spacer designs accommodate wide gaps between shaft ends, greatly increase parallel (radial) offset capabilities, and provide a second elastomeric insert for additional vibration damping capability.

The CJ Series also offers standard drop-out designs for faster, easier equipment maintenance and elastomer replacement, plus shaft-to-flange and flange-to-flange designs for flywheel-type or limited-space applications.

New GS Series couplings introduce a special Lovejoy design that precompresses its elastomeric insert, resulting in high torsional stiffness that provides zero-backlash operation for precision motion control in servo and positioning drives, and eliminating vibration in machine-tool spindle drives.

The GS Series also presents a full range of elastomer hardnesses to cover all types of motion control applications.

The CJ Series is offered in 17 different hub sizes, which includes hub outside diameters ranging from 30 to 420mm.

Hub materials are aluminium, sintered iron, cast iron, nodular iron and steel, depending on the hub size.

The CJ Series is available from stock in standard inch and DIN bore and keyway combinations.

Taper bores and SAE splines are available to SAE J7444, 5480, or 5482 standards and can be obtained in set screw, single slot clamping, or Lovejoy's L-Loc design.

The GS Series is offered in nine different hub sizes ranging from 30 to 135mm outside hub diameter - and is available in five aluminium sizes and four steel sizes.

Varying hub styles, like the CJ Series, are available to accommodate standard inch and DIN bore and keyway needs.

The GS Series additionally offers a double split clamp design for applications requiring precise torsional stiffness.

Elastomeric inserts, moulded in one-piece asterisk shapes called "spiders", offer four different hardness ratings.

Standard CJ Series polyurethane spiders are rated for normal operation in ambient temperatures ranging from -50 to +120C varying with hardness.

Special GS spiders, made of urethane, have slightly lower ratings topping between 80 and 110C, but with higher resistance to oil, grease, abrasives, moisture, many solvents and atmospheric ozone.

Spider hardness alternatives allow the coupling to serve a wide range of torsional stiffness needs, from relatively soft for good vibration damping properties to relatively stiff for high torque.

Spiders alternatives also can be used to help counter various environmental conditions within a particular application (eg high resistance to humidity).

Spider material is colour coded for positive identification of hardness rating.

Operating "in compression", with torque passing from driving to driven hub jaws through the spider serving as a cushion between them, the curved jaw design eliminates metal-to-metal wear, requires no lubrication, assures "failsafe" service that continues transmitting torque in the unlikely event of elastomer failure, and can provide electrical isolation between driving/driven sides.

Basic three-piece assembly is easily installed, even where blind fit is necessary.