Universal joint

Universal joint

File:Universal Shaft.ogv

Spicer u-joint advert in Automobile Trade Journal 1916

UJoint

UJoint 3D

Cardan Shaft

Universal joint (also known as a U-joint, universal coupling, Cardan joint, or Hooke's joint) is a mechanical joint used to connect two non-parallel shafts at an angle, allowing them to rotate freely while transmitting torque. The basic design of a universal joint consists of a pair of hinges located close together, oriented at 90° to each other, connected by a cross shaft.

Design and Principle

The universal joint is considered a significant invention in the field of mechanics and engineering. Its design allows for the transmission of power between shafts that are not aligned on the same plane. The key components of a universal joint are the cross or spider, which has four legs, and two yokes, which are attached to the shafts. The cross sits inside the yokes, and the configuration allows the joint to move in any direction, accommodating angular misalignment of the shafts.

Applications

Universal joints are widely used in various applications where shaft alignment cannot be maintained or an angular misalignment is desirable. Common applications include:

• Automobiles: In the drivetrain and steering mechanisms to transmit power from the engine to the wheels.
• Aircraft: In the control mechanisms to transmit pilot inputs to the control surfaces.
• Industrial machinery: In conveyors, blowers, and other machinery requiring power transmission at varied angles.
• Driveshafts: As a critical component in the transmission of power in machinery and vehicles.

Advantages and Limitations

The primary advantage of a universal joint is its ability to transmit torque and rotational motion in applications where direct alignment is not possible. However, one of the limitations of a simple universal joint is its inability to maintain a constant velocity across the joint during rotation, which can lead to vibrations and wear over time. This issue is addressed in some applications by using a constant-velocity joint (CV joint).

Types of Universal Joints

Several types of universal joints exist, each designed for specific applications and requirements. These include:

• Single Universal Joint: The simplest form, used in applications where a single bend in the shaft alignment is required.
• Double Universal Joint: Consists of two universal joints combined, allowing for greater flexibility in angular misalignment.
• Constant Velocity Universal Joint: Designed to overcome the constant velocity issue, providing smoother power transmission.

Maintenance

Maintenance of universal joints involves regular lubrication to prevent wear and tear and checking for signs of wear or damage. In automotive applications, worn universal joints can lead to vibrations, noise, and eventual failure of the drivetrain components.

Conclusion

The universal joint is a critical component in the field of mechanical engineering, offering flexibility in the transmission of power between misaligned shafts. Its invention has enabled the development of complex mechanical systems in automotive, industrial, and aerospace applications.