There are many types of U-Joints, a few of which are extremely complex. The easiest category named Cardan U-Joints, will be either block-and-pin or bearing-and-cross types.
U-joints are available with two hub designs solid and bored. Sturdy hubs do not have a machined hole. Bored hubs possess a hole and are called for the hole condition; round, hex, or sq . style. Two bored models that deviate from these common shapes are splined, which have longitudinal grooves inside the bore; and keyed, that have keyways to avoid rotation of the U-joint on the matching shaft.
Using the incorrect lube can result in burned trunnions.
Unless usually recommended, use a high quality E.P. (excessive pressure) grease to services 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 action between two flanges that are fork-shaped (a yoke) and having a hole (vision) radially through the attention that is linked by a cross. They let larger angles than versatile couplings and are used in applications where high misalignment needs to be accommodated (1 to 30 degrees).
Always make sure new, fresh grease is evident by all four U-joint seals.
Can be due to operating angles which are too big.
Can be caused by a bent or U Joint sprung yoke.
Overloading a drive shaft could cause yoke ears to bend. Bearings won’t roll in the bearing cap if the yoke ears are not aligned. If the bearings stop rolling, they continue to be stationary and will “beat themselves” into the surface area of the cross.
A “frozen” slip assembly will not allow the travel shaft to lengthen or shorten. Every time the drive shaft attempts 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 will be the effect of a frozen slide are always evident on the front and back floors of the cross trunnion.
Improper torque upon U-bolt nuts could cause brinelling.
Most companies 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.