Cranes, airplanes, cars, trucks, and industrial equipment rely on universal joints. U-joints transmit torque and rotation between two shafts that aren’t in a straight line. They’re essential for the performance of the equipment.
Having the right replacement joint on hand avoids downtime. Learn more about finding universal joints by size and how to choose the correct part.
U-Joint Configurations
Before looking at universal joint sizes, the purchaser must know which type of u-joint they need. The types of bearing caps include:
- Plain round
- Grooved
- Welded plate
- Knurled (textured)
- Slotted
- Wing
A variety of joint configurations are possible. Four grooved or four plain round bearings are standard joint options.
Two caps of one style and two of another are available as well. For example, a u-joint could have two welded plates and two plain round bearings. The lock rings can be located on the outside or near the bearing caps’ inside end.
Measuring U-Joints to Find the Right Size
Universal joint sizes are classified by series. Each series has a specific overall width and cap diameter.
If the old universal joint is on-site, measuring it directly is possible. Otherwise, measuring components of the vehicle or equipment that need the joint will be necessary. Using a good set of calipers for the u-joint measurements is recommended.
Measuring the U-Joint
If the old u-joint is available, measure the outside distance across the u-joint. Leave the caps on for this measurement.
If the joint has plain bearing caps with the lock rings on the outside end, measure the overall width of the joint. If the lock rings are near the inside end of the bearing caps, measure from the inner edge of one lock-ring groove to the other.
Then, measure the diameter of the caps. Check all the caps because they can be different.
Measuring the Driveshaft
If the old u-joint isn’t available, start by measuring the distance between the lugs of the transmission and the pinion yokes. Then, measure the distance between the snap rings of the driveshaft yokes. These measurements produce the overall widths of the u-joints.
To get the cap diameters, measure the yoke gap and the diameter at the cap location. Be sure to measure all the width and depth dimensions. If they aren’t the same, a conversion u-joint may be necessary.
Universal Joint Sizes and Strength Ratings
The strength of the joint depends on several factors, including:
- Body design
- Material type
- Cap size
- The presence of a grease fitting
Manufacturers usually provide information on the lifetime operating torque. They should also provide the yield torque. Yield torque is the point at which the joint starts to deform.
In general, larger and thicker caps are stronger. Joints are usually made from stainless or alloy steel.
Finding Universal Joints by Size
Universal joints are an essential part of industrial vehicles and equipment. Finding universal joints by size doesn’t need to be complicated. Careful measurements will help you choose the correct size joint.
Kor-Pak offers a wide range of joint-size options. We specialize in industrial supplies and equipment. We offer quality OEM and aftermarket parts to keep essential equipment running.
Contact Kor-Pak today for a quote on universal joints or expert guidance on choosing the right size joint.