U Joint

There are many varieties of U-Joints, some of which are very complex. The easiest category named Cardan U-Joints, happen to be either block-and-pin or bearing-and-cross types.

U-joints can be found with two hub styles solid and bored. Sound hubs do not have a machined hole. Bored hubs own a hole and so are named for the hole form; round, hex, or sq . style. Two bored styles that deviate from these prevalent shapes are splined, which have longitudinal grooves within the bore; and keyed, which have keyways to avoid rotation of the U-joint on the matching shaft.

Using the incorrect lube can cause burned trunnions.
Unless or else recommended, use a superior quality E.P. (intense pressure) grease to services most vehicular, industrial and U Joint auxiliary travel shaft applications.
Mechanically flexible U-Joints accommodate end movement by by using a telescoping shaft (sq . shafting or splines). U-Joints function by a sliding motion between two flanges that are fork-designed (a yoke) and having a hole (eyes) radially through the attention that is linked by a cross. They allow larger angles than versatile couplings and are being used in applications where large misalignment has to be accommodated (1 to 30 degrees).

Always make sure fresh, fresh grease is evident in all U-joint seals.

Can be caused by operating angles which are too big.
Can be the effect of a bent or perhaps sprung yoke.
Overloading a drive shaft can cause yoke ears to bend. Bearings won’t roll in the bearing cap if the yoke ears are not aligned. If the bearings quit rolling, they continue to be stationary and will “beat themselves” in to the surface of the cross.
A “frozen” slip assembly won’t allow the drive shaft to lengthen or shorten. Each and every time the travel shaft attempts to shorten, the load will be transmitted in to the bearings and they will indicate the cross trunnion. Unlike brinnell marks caused by torque, brinnell marks that are caused by a frozen slip are generally evident on leading and back surfaces of the cross trunnion.
Improper torque on U-bolt nuts can cause brinelling.
Most suppliers publish the recommended torque for a U-bolt nut.
Improper lube procedures, where recommended purging isn’t accomplished, can cause one or more bearings to be starved for grease.