A universal joint (U-joint) is a key component of a propeller shaft that allows it to transmit rotary motion and torque between two shafts that are not perfectly aligned.
⚙️ Function of a Universal Joint
- Connects sections of the propeller shaft to the transmission and differential.
- Allows the shaft to bend or flex as the suspension moves or as angles between components change.
- Ensures smooth transmission of power even when the input and output shafts are at different angles.
🛞 How It Works
- The U-joint consists of a cross-shaped metal piece (called a spider) with bearings at each end.
- Each end connects to a yoke attached to the shafts.
- As the shafts rotate, the U-joint flexes, accommodating angular misalignment while keeping torque transmission continuous.
🧰 Why U-Joints Are Important
- Without U-joints, the propeller shaft could bind or break when the vehicle moves over bumps or the suspension travels.
- They reduce vibration and prevent excessive wear in the drivetrain.
⚡ Types of Universal Joints
- Cross and bearing U-joint – Most common in standard propeller shafts.
- Double Cardan joint – Used in high-angle drives, reduces vibration.
Summary:
In short, a universal joint acts as a flexible coupling that allows the propeller shaft to transmit power efficiently while accommodating changes in angle due to suspension movement or chassis geometry.
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