U Joint

There are many types of U-Joints, a few of which are incredibly complex. The easiest category called Cardan U-Joints, happen to be either block-and-pin or bearing-and-cross types.

U-joints are available with two hub models solid and bored. Stable hubs do not have a machined hole. Bored hubs own a hole and so are known as for the hole shape; round, hex, or sq . style. Two bored models that deviate from these common 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 wrong lube can result in burned trunnions.
Unless or else recommended, use a superior quality E.P. (extreme pressure) grease to service most vehicular, industrial and auxiliary drive shaft applications.
Mechanically flexible U-Joints accommodate end movement simply by using a telescoping shaft (sq . shafting or splines). U-Joints function by a sliding motion between two flanges that happen to be fork-formed (a yoke) and having a hole (vision) radially through the eye that is linked by a cross. They allow larger angles than versatile couplings and are being used in applications where great misalignment needs to be accommodated (1 to 30 degrees).

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

Can be caused by operating angles which are too big.
Can be caused by a bent or sprung yoke.
Overloading a travel 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 stay stationary and will “beat themselves” into the area of the cross.
A “frozen” slip assembly won’t allow the drive shaft to lengthen or shorten. Each and every time the travel shaft tries to shorten, the strain will be transmitted into the bearings and they’ll indicate the cross trunnion. U Joint Unlike brinnell marks caused by torque, brinnell marks that are caused by a frozen slip are constantly evident on the front and back floors of the cross trunnion.
Improper torque on U-bolt nuts could cause brinelling.
Most suppliers publish the recommended torque for a U-bolt nut.
Improper lube procedures, where recommended purging isn’t accomplished, can cause a number of bearings to be starved for grease.