Home » Knowledge Base Articles » How Constant Velocity (CV) Joints Work

How Constant Velocity (CV) Joints Work

A simple diagram and explanation of how CV joints work.
If you have ever looked under a Jeep vehicle, then you may have seen the drive shafts and the large, cross like devices that connects them to the transfer case. This device is generally termed as a double cardan u-joint. This style of joint is defined as 2 single u-joints mounted back to back and joined at the center by a yoke.  This style of connection works for many vehicle applications. The first cardan (U-joint) is used for the driveshaft angle, while the 2nd cardan is used to eliminate velocity errors (drive shaft vibrations).  The 2nd cardan is also used as the Constant Velocity joint in this particular setup.

To have a driveshaft transmit power without increasing vibration and function at a high angle, a true Constant Velocity joint would have to be used.  This type of joint utilizes a series of ball bearings within a coupler to provide a smooth transfer of power at a constant rotational speed. These are mainly used on vehicles with independent suspension systems.  Other applications can be any vehicle with a full time four wheel drive system and a solid front axle. The angle of operation for this type of unit is increased over the standard cardan style.  The axle joint is protected by a rubber boot with grease inside to help with lubrication.  If the boot becomes torn, contaminants can get inside and grease can be lost causing premature failure and wear.

Article Type: 
How It Works