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A universal joint (UJ) is a flexible double-pivoted joint that enables driving power to be transmitted through two shafts that are at an angle to each other. Here’s how it works:

  1. Components: The universal joint consists of two Y-shaped yokes and a cross-shaped member known as the spider. The four arms of the spider are assembled into bearings in the ends of the two yokes.
  2. Flexibility: The design of the universal joint allows it to accommodate variations in alignment between the driving and driven shafts. This flexibility is crucial for transmitting power smoothly even when the shafts are not perfectly aligned.
  3. Angular Transmission: When the driving shaft rotates, it causes the spider to pivot, transferring motion to the driven shaft. The universal joint allows this motion to occur even if the shafts are at an angle to each other.
  4. Speed Variation: In traditional cross-and-two-yoke universal joints, there is some variation in speed between the driving and driven shafts, especially at high angles. This speed variation can lead to increased wear on the joint and other components.
  5. Constant Velocity Joints (CV Joints): To address the speed variation issue, many modern vehicles use constant velocity joints. These joints maintain a more consistent speed between the driving and driven shafts, reducing wear and improving performance, especially in front-wheel-drive vehicles.
  6. Alternative Names: The universal joint is also known as a Hooke joint or Cardan joint.

Overall, the universal joint is a fundamental component in many mechanical systems, providing flexibility and reliable power transmission between shafts that are not perfectly aligned.


  • Hardy-spicer universal joint
  • Impact swivel ball universal joint
  • Rzeppa-type universal joint
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