This is an interesting type of joint that you would find under a rear wheel drive or 4WD car or a large truck like a bread lorry and it transmits power between rotating shafts which themselves are not in line and may move relative to one another. For example this happens when the suspension on the rear wheels allows them to move up and down relative to the rest of the car.
A universal joint coupling two rotating shafts which are currently in line
A universal joint coupling two rotating shafts which are currently in line
Now the rear suspension allows the left hand drive shaft to angle up and the universal joint allows it to keep being driven from the right hand shaft so the back wheels keep turning as the car goes over bumps in the road.
A universal joint in action transmitting power to an inclined shaft
The Troutbeck School 