Lovejoy Spider Couplings at ProSource Industrial
One of the most widely-used coupling types is an elastomeric design known as the jaw coupling. The design is made up of two hubs, each with two or more, thick protrusions around their perimeters called jaws. These “jaws” mesh together loosely when the two hubs come together. That’s where the spider comes in. Designed to fill the gaps between the coupling’s jaws are blocks of elastomeric material generally fashioned into the shape of an asterisk that resembles a spider, which is how they came to be called spiders. These spiders are key to optimal jaw coupling performance.
Lovejoy spider couplings come in a variety of styles to meet requirements for different applications, as do the spiders within these jaw-type couplings. The spider type chosen can make all the difference when it comes to factors such as response to vibration, temperature, chemicals, misalignment, high RPM, and space limitations, as well as ease of installation and removal.
Jaw couplings are recommended for use in continuous-duty electric motor-driven machinery, gearboxes, pumps, and more. These elastomeric couplings fall into one of two different categories based on the way their elastomeric element transmits torque, meaning that the element is either considered to be “in compression” or “in shear.”
Advantages of Lovejoy Spider Couplings
Both types of jaw couplings– compression and shear– offer advantages that earn them their uses in different application settings. In situations where compression style couplings are preferred, it is usually because of these main benefits. Elastomers, especially synthetic rubber ones, have a higher load capacity in compression than they do in shear. This means that compression types can transmit higher torque and handle greater overload than their shear counterparts.
Compression type couplings also offer a greater degree of torsional stiffness– or less twist between the hubs– than shear types. They are also considered “failsafe” because coupling is not necessarily rendered inoperable in the event of the spider element breaking away. In this situation, the driving jaws simply transition to contact the driven jaws directly while the coupling continues its function. And lastly, a simple construction of a spider between two metal hubs yields easy installation as well as visual inspection when necessary.
Spider Design Types
Lovejoy spider couplings also are available in a variety of materials in four basic mechanical designs to allow for further options to meet application requirements more fully. These types are as follows:
- Standard Solid-Center Spider– This type is the most commonly used in general power transmission applications, affording a suitable gap that remains constant for the most part.
- Open-Center Type (OCT)– This coupling type generally suits close BE situations in which equipment must be positioned very closely together. This design also has no full-diameter support, so it has maximum speed limitations of 1,750 RPM.
- Snap-Wrap– This open-ended, flat strip design connects the spider legs around the perimeter of the coupling rather than at the center, allowing easy installation/removal without disturbing alignment.
- Load Cushions– As small, separate blocks, these couplings can be installed and removed radially, which can be invaluable in heavy-duty applications. These load cushions must be held in place by a collar.
Application Criteria for Spider Choice
When determining the most suitable spider type for your application consider the following:
- Actual torque necessary at the driven shaft
- Vibration, both linear and torsional
- Shaft-to-shaft alignment Ambient conditions including temperature range, exposure to contaminants, etc.
- Start-stop-reverse requirements
- Axial movement, BE or other spatial limitations
- Restrictions for installation and maintenance
Work with ProSource as your coupling vendor, and we can help steer you toward the right type of Lovejoy spider coupling for your application. If we don’t stock what you need, we can get it for you.