There are many types of U-Joints, some of which are extremely complex. The simplest category named Cardan U-Joints, will be either block-and-pin or bearing-and-cross types.
U-joints are available with two hub types solid and bored. Sturdy hubs do not have a machined hole. Bored hubs have a hole and so are named for the hole shape; round, hex, or sq . style. Two bored styles that deviate from these common shapes are splined, that have longitudinal grooves inside bore; and keyed, that have keyways to U Joint prevent rotation of the U-joint on the matching shaft.
Using the incorrect lube can result in burned trunnions.
Unless or else recommended, use a superior quality E.P. (severe pressure) grease to program most vehicular, industrial and auxiliary drive shaft applications.
Mechanically flexible U-Joints accommodate end movement simply by by using a telescoping shaft (square shafting or splines). U-Joints function by a sliding action between two flanges that happen to be fork-designed (a yoke) and having a hole (eyesight) radially through the eye that is linked by a cross. They enable larger angles than versatile couplings and are being used in applications where high misalignment needs to be accommodated (1 to 30 degrees).
Always make sure fresh, fresh grease is evident for all U-joint seals.
Can be caused by operating angles which are too big.
Can be the effect of a bent or sprung yoke.
Overloading a drive shaft can cause yoke ears to bend. Bearings will not roll in the bearing cap if the yoke ears are not aligned. If the bearings quit rolling, they continue to be stationary and can “beat themselves” in to the surface area of the cross.
A “frozen” slip assembly won’t allow the travel shaft to lengthen or shorten. Every time the drive shaft tries to shorten, the load will be transmitted in to the bearings and they’ll indicate the cross trunnion. Unlike brinnell marks caused by torque, brinnell marks that are caused by a frozen slide are always evident on the front and back areas of the cross trunnion.
Improper torque about U-bolt nuts can cause brinelling.
Most producers publish the recommended torque for a U-bolt nut.
Improper lube procedures, where recommended purging is not accomplished, can cause a number of bearings to be starved for grease.