DXP Cortech Industrial Pumps

When to Use Rigid Coupling on Pumps

There are two primary types of pump couplings: rigid couplings and flexible couplings. Both can have their advantages and disadvantages. Which type of coupling to use will depend on the pump equipment and application.

Rigid vs. Flexible Coupling

It’s pretty simple to understand the main difference between a rigid and flexible coupling. One provides a rigid connection with no flexibility. This ensures the two shafts are firmly connected with precision alignment. Ultimately, a rigid coupling can provide smoother transmission of torque throughout the pump system. It requires accurate alignment with little-to-no tolerance for misalignment.

Flexible coupling provides some flexibility to compensate for shafts which are slightly misaligned. The connection has more tolerance. However, torque power is generally decreased with flexible pump couplings compared to rigid. 

Advantages and Disadvantages of Rigid Couplings

Rigid couplings can be more difficult to install and maintain because they require such precision alignment. They should be inspected regularly for wear, lubrication and any slight misalignments that can start to occur over time. When utilized properly, a rigid coupling can significantly reduce backlash at zero or near-zero levels. They are simple in design and much more affordable. Operators requiring higher torque ratings may prefer rigid couplings for certain applications. Here are some of the advantages of rigid couplings:

• Improved torque transmission

• Lower cost

• Optimized shaft alignment

• Simplicity

• Increased torsional stiffness

• Reduced backlash

Rigid Coupling Applications

Rigid couplings are best suited for high-torque pumping applications, push-pull use cases and shaft support applications. Examples include semiconductor manufacturing, product packaging and machining tools. Rigid couplings can be used on horizontal and vertical pumps, but they are most commonly utilized for vertical pump applications that require higher torque.

Types of Rigid Couplings

There are multiple types of rigid couplings:

Flanged—Flanged couplings are utilized when there is clear access to both shafts. The coupling is composed of two halves, which are bolted together to form the rigid connection.

Split—Split couplings (also known as clamp couplings) are used when access is limited on one side. The coupling is essentially a sleeve that has a horizontal split along the shaft. It is clamped and bolted together for the rigid connection. Split couplings are used primarily on vertical pumps.

Compression—Compression couplings are designed with three pieces. There will be a compressible core and two coupling halves applying force to the core once connected. This allows for rigid coupling when the use of keys and keyways is not an option as required for both split and flanged couplings.

To learn more about rigid coupling and to find the right pump coupling solution for your specific pump system, contact DXP Pacific today.