LOVEJOY Keyless Rigid Coupling

Lovejoy rigid couplings or shaft locking devices are designed for applications where a shaft connects to a hub. These rigid couplings connect equipment to transmit power, as well as prevent vibration, shock, backlash, misalignment & overload.


Keyless Rigid Coupling

Lovejoy rigid couplings are ideal for connecting hubs to two shafts, so that no relative motion occurs between them and they operate as one shaft. They do so by using a keyless mechanical interference fit, which helps withstand axial thrust & transmit torque. These keyless Lovejoy rigid couplings wrap around soft / hard shafts without marring and feature vibration resistant screws. These couplings have the ability to adjust angular timing and axial position, which might lead to early equipment failure. These couplings provide rigidity in continuous-motion and moderate to high torque applications like robots, servo motors & machine tools, and allow minimal backlash between shafts of the same dimension. Lovejoy rigid couplings are used for vertical pumps in the paper, steel, food & beverage, transportation, wastewater, lumber, mining and construction industries. Raptor Supplies, a trusted distributor of Lovejoy rigid couplings, also offers coupling spacers, sleeve gear couplings, gaskets, hydraulic tanks and related accessories.


Lovejoy rigid couplings offer a wide combination of features, making them useful for continuous motion and moderate to high torque applications in the paper, steel, food & beverage, transportation, wastewater, lumber, mining and construction industries.

Working Mechanism

Lovejoy rigid couplings utilise a keyless mechanical interference fit for transmitting torque and tolerating axial thrust. This mechanical interference fit uses screw tension in these shaft locking devices by converting it into radial pressure via an inclined plane. The radial pressure expands the units to minimise the gap between the shaft & the hub and operate them as a single shaft. The contact pressure created using a shaft locking device allows shorter hubs to be used or more torque to be transmitted. These units use the friction bond between the unit and the hub / shaft to create a zero backlash connection that can be easily released to remove the mechanical interference fit.


  • Lovejoy shaft locking devices are ideal for connecting hubs solidly to shafts, with the help of a keyless mechanical interference fit. They allow transmission of torque and the capability to withstand axial thrust.
  • These shaft locking devices provide axial positioning and angular timing of the shaft to ensure accurate alignment.
  • Lovejoy shaft locking devices feature zero backlash of components through a mechanical interference fit between the shaft and mounted components.
  • These Lovejoy rigid couplings are capable of being mounted on existing keyways to eliminate the cost of remachining worn and damaged keyways.
  • These shaft locking devices are infinitely & radially adjustable to ensure precise timing and synchronisation.
  • Lovejoy shaft locking devices offer excellent resistance against dynamic, reversing and shock loads.
  • These rigid couplings provide easy installation and removal without damaging the hub or shaft, reducing maintenance cost.
  • Lovejoy shaft locking devices also help in reducing shaft stress by removing damaged splines and keyways.

Compatible Accessories

  • Lovejoy Hubs: The brand's hubs are used along with spiders to form Lovejoy rigid couplings.


  • Clean the inner diameter of Lovejoy shaft locking devices, the hub & the hub shoulder that the shaft locking device will be mounted against. Dress or repair any nicks, burrs, dents, gouges or raised metal on both inner and outer surfaces.
  • Gently lubricate the outer diameter surface of the hub and the inner diameter surface of the ring in the shaft locking device.
  • Clean and gently lubricate the inner hub diameter and the outer shaft diameter.
  • Slide the hub on the shaft to the exact location and tighten three or four alternating tightening bolts manually on the rigid coupling while ensuring that it is mounted parallel to the shaft.
  • If the coupling is a Lovejoy disc style coupling, then install the spacer assemblies, disc packs and bolts prior to fastening the bolts.
  • Manually tighten all fastening bolts and double check the rigid coupling to ensure the right position against the shoulder on the hub.
  • If the coupling is a DILRA or DIRA style adjustable coupling, then leave a gap between the disc pack bolt heads and Lovejoy rigid coupling.
  • With the help of a calibrated torque wrench, fasten each bolt in either a star shaped or sequential pattern.

Frequently Asked Questions

What are the methods of reducing or minimising backlash?

Some effective methods of controlling and minimising backlash are:

  • Changing worn or faulty components in the system which add to excessive backlash, like worn couplings or inserts.
  • Decreasing the effects of backlash by rotating shafts to maintain torque at a required level and direction.
  • Making use of temporary mechanical means, like a mechanic's wire or duct tape, to momentarily override the coupling's ability to experience backlash.

What is backlash in couplings?

Backlash is defined as the angular movement between mating parts in any mechanical system. Coupling backlash is common, and to a point, preferable in many types of couplings. Usually, excessive coupling backlash is caused by a worn coupling insert.

Do we require keyways with Lovejoy rigid couplings?

Keyways are not always necessary. They are only used with couplings that are required to maintain radial alignment between shafts and support loads with high torque. For applications in which radial alignment and high torque are not considerations, keyways may not be required.

What is the difference between rigid and flexible couplings?

Rigid couplings offer a rigid connection between two shafts that are firmly connected, and facilitate the coupling to transfer torque smoothly throughout the system. Flexible couplings provide flexible connections, and there is a chance of losing some torque during transmission.

What are the advantages of rigid couplings?

Lovejoy rigid couplings are designed to accurately transfer torque from one shaft to the other attached shaft. These rigid couplings provide low cost of production as manufacturers can create both standard and custom rigid couplings at cost-effective rates. They also provide accuracy, with nearly zero backlash and zero windup.

What are the different types of rigid couplings?

There are three different types of rigid couplings: flanged, sleeve and clamped. Rigid couplings are employed when shafts are accurately in line. They are only ideal for shafts in close alignment.

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