There are many varieties of U-Joints, some of which are extremely complex. The simplest category known as Cardan U-Joints, will be either block-and-pin or bearing-and-cross types.
U-joints are available with two hub models solid and bored. Sturdy hubs do not have a machined hole. Bored hubs currently have a hole and so are known as for the hole condition; round, hex, or square style. Two bored variations that deviate from these prevalent shapes are splined, that have longitudinal grooves within the bore; and keyed, that have keyways to avoid rotation of the U-joint on the matching shaft.
Using the wrong lube can bring about burned trunnions.
Unless in any other case recommended, use a high quality E.P. (serious pressure) grease to support most vehicular, professional and U Joint auxiliary drive shaft applications.
Mechanically flexible U-Joints accommodate end movement simply by using a telescoping shaft (square shafting or splines). U-Joints function by a sliding motion between two flanges that will be fork-shaped (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 must be accommodated (1 to 30 degrees).
Always make sure fresh, fresh grease is evident for all U-joint seals.
Can be due to operating angles which are too large.
Can be caused by a bent or perhaps 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 will “beat themselves” in to the surface of the cross.
A “frozen” slip assembly will not allow the travel shaft to lengthen or shorten. Each time the drive shaft tries to shorten, the load will be transmitted into the bearings and they’ll indicate the cross trunnion. Unlike brinnell marks caused by torque, brinnell marks that are caused by a frozen slip are usually evident on the front and back floors of the cross trunnion.
Improper torque in 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 a number of bearings to be starved for grease.