Today, let’s go back to the drawing board and start from the top: what is a universal joint, what does it do, and how does it outperform other types of couplings?
A universal joint, also known as U-joint or cardan joint, is a mechanical coupling that allows for the transmission of torque and rotational motion between two non-aligned shafts. It consists of two yokes that are connected by a cross-shaped component, known as the spider or the cross. The yokes are attached to the ends of the two shafts, and the cross rotates and tilts within them, allowing the shafts to rotate at different angles without losing power transmission.
Why should you use this type of coupling? Well, in an engineer’s idea of a perfect world, input and output shafts should be perfectly aligned. Of course, the real world looks much different. In practice, displacement during operation, for example due to a technical restriction or vibration, is often unavoidable. These misalignments can be overcome with a well selected universal joint or drive shaft.
Universal joints can be found between motors and end effectors or gearboxes where other couplings are not an option, or where the characteristics of couplings alone do not suffice due to angular or parallel misalignment or other demanding operating conditions.
Let's examine the different power transmission conditions that would require a universal joint. If angular misalignment is greater than 5 degrees, a universal joint may be the only viable coupling option. This can be the case if the motor cannot be installed very precisely, or if the motor moves during operation or after installation. Sometimes the motor has to be placed at a higher angle to the outbound shaft due to other factors.
Single joints can operate at up to 45 degrees, and double joints and telescoping drive shafts can operate at up to 90 degrees. Parallel misalignment often requires a double joint or a telescoping drive shaft. For example, sometimes the motor cannot be added in line with the outgoing shaft because there is no room, so it is plugged underneath or above the direct line of the shaft.
High torques and low or moderate speeds are often discouraged for most couplings. Couplings with the highest torque ratings, such as jaw or elastomer couplings, are also the least forgiving on angular misalignment. Conveying systems might require a relatively high torque at elevated angles, which demands the high torque and high angle capabilities of a universal joint. The same applies for manual remote operating systems of flaps or other types of valves.
High temperature or highly corrosive environments can prevent the use of flexible couplings and require a universal joint. With special lubricants or dry lubricant coatings, universal joints can operate in higher temperatures than jaw or elastomer couplings. Ovens or other high temperature applications with moving parts, like feeders or conveyors, are another likely application.
As you can tell, there is plenty of upside to the versatile universal joint, and thanks to our state-of-the-art production facility in Illinois, U.S. of A., we can customize them to suit almost any application you may have in mind. You can explore the possibilities HERE.
