What’s the difference between a universal joint and a constant velocity joint?



If a UJ transmits rotation from one axle to another, surely it has to transfer the velocity, otherwise the axles will get twisted because one is rotating faster. If it does transmit velocity, then what is the difference between it and a constant velocity joint?

In: Engineering

have you already taken a look at the wikipedia page?


Both essentially serve identical purposes, the transfer or rotational force from a fixed axis to a variable axis. The difference comes down to the design. A universal joint connects the 2 axle ends via an x shaped coupler with bearings on it. You can see these under larger box trucks and on the front drive of larger 4×4 trucks, anywhere a connection needs to be made from a fixed transmission to a moving axle or tire.

A cv joint uses a more complex joint hidden under a boot filled with grease. It’s harder to explain simply but basically there is an inner socket and an outer “bone” the bone goes into he socket and bearings go between the bone and the socket that transfer the energy to or from the bone. The bearings are round so the bone can move int he socket while still transferring rotational force.