Common Terms

Glossary of Common Driveshaft Terms

Bearing Plate	A retainer plate fixed to the back of a round bearing used to position the bearing in the yoke.
Balancing	A procedure in which the distribution of mass in a rotating body is checked and altered where necessary to ensure that vibration does not occur during operation.
Ball Seat	A full or segmented angular contact bearing located in a socket that supports and centers the ball stud.
Ball Stud	A yoke generally used in CV applications which incorporates a stud onto which a ball is mounted.
Brinnelling	Failure that occurs when the static forces between two curved surfaces in contact result in local yielding of one or both mating members to produce permanent surface discontinuity. Example: Needle roller indents on a u-joint trunnion or trunnions.
Cardan Universal Joint	A non-constant velocity universal joint consisting of two yokes connected by a cross through four bearings and driveable by external sources.
Center Support	A rolling bearing element surrounded by rubber, mounted in a bracket configuration used to mount the support to an outside structure.
Centering Socket Yoke	A yoke assembly that functions as a self-aligning bearing and provides support and a means of centering in double cardan universal joints.
Companion Flange	A flanged member that attaches a driveline to drivetrain components, typically affixed by some bolt-together method.
Critical Speed	The speed at which the rotational speed of a shaft coincides with the natural vibration frequency of the shaft, causing a dynamically unstable condition.
Cross and Bearing Kit	Drive member with four equally spaced trunnions in the same plane and four bearing cups with attaching parts. Also referred to as a universal joint kit or u-joint kit.
Cross Hole	A through hole located in each ear of a yoke used to locate a round bearing.
Double Cardan Universal Joint	A near constant velocity universal joint consisting of two trunnion type Cardan universal joints whose trunnion yokes are connected by a coupling yoke or H-yoke with internal supporting and centering means.
Driveline	An assembly of one or more driveshafts with provisions for axial movement, which transmits torque and/or rotary motion.
Driveshaft	An assembly of one or two universal joints connected to a solid or tubular shaft member.
Driveshaft Length Center to Center	The distance between the outermost universal joint centers on a driveshaft.
Drive Train	Term used for the unit of all components from the Transmission to Rear differential. Also referred to as Power Train.
Ear	One of two projecting parts of a yoke symmetrically located with respect to the rotational axis.
End Yoke	A yoke which attaches a driveshaft to another drive train component such as the transmission.
Flange Yoke	The yoke which attaches the driveshaft assembly to a companion flange.
Flinger	A protective shield used in front of and behind the bearing and rubber on many center supports and end yokes.
Galling	Failure that occurs when two sliding surfaces are subjected to such a combination of loads, sliding velocities, temperatures, environments, and lubricants, that massive surface destruction is caused by welding and tearing, plowing, and gouging. Example: Bearing cup/trunnion end galling on a cross and bearing kit.
Glidecote	The blue, nylon, wear-resistant coating on yoke shafts and tube shafts.
H-Yoke	A double yoke which connects the two halves of a double cardan universal joint.
Half Round Yoke Cross Hole	A semicircular hole located on the end of each ear of some end yokes and used to locate a round bearing.
Hub	The central part of a yoke used for attachment to another member.
Inside Lock-up	Term referring to either a cross and bearing kit or a yoke that utilizes a snap ring seated in a groove in the bearing cups and located inside the yoke ears to retain the kit in the yoke.
Joint Angle	The angle described by the intersection of rotational axis of the input and output members of a universal joint and measured on the same plane described by these areas.
Knuckle	A slange term used when referring to some driveshaft joint parts and components.
Liner	A sound and vibrational deadening material added to the inside surfaces of a tube.
Lock-Up	The dimensional distance between the two retaining surfaces in a driveline component used to locate the bearing surfaces.
Midship Stub Shaft.	A short shaft, generally splined, used in applications requiring more than one driveshaft. It mounts through the center of a support bearing and allows an additional driveshaft component to be fixed.
Outside Lock-Up	Term referring to either a cross and bearing kit or a yoke that utilizes a retaining ring in a groove near the outside edge of the yoke ear, rested against the outside face of the bearing cup.
Phase/Phase Angle	The relative positioning of the universal joint yokes on a driveshaft or driveline.
Retaining Ring	A removable ring used as a shoulder to retain and position a round bearing in a hole.
Ring Groove Round Bearing	The surface used for positioning a round bearing with a retaining ring. Consists of a round bearing cup with needle rollers designed to ride on a trunnion.
Seal	A flexible member which prevents the escape of lubricant and the entrance of foreign matter.
Slip Movement	A permissible length of axial movement.
Slip Stub Shaft	A short, machined shaft, generally splined, which, when used with a slip yoke allows axial movement.
Slip Yoke	A yoke which allows axial movement.
Snap Ring	Same as RETAINING RING.
Strap Bearing Clamp	A semi circular device that conforms to the bearing profile holding them in place in half round and some DC yokes.
Swaged Tubing	A tube with one or both ends having a smaller diameter then the middle section.
Swing Diameter	The maximum diameter of the circular path described by a rotating universal joint.
Thrust End	The end of a cross trunnion used as a thrust surface.
T.I.R.	Total Indicator Reading on a specific point thru 1 revolution of a shaft.
Torsional Damper	A mechanical device, generally an inertia ring, attached to a drivetrain component by means of a rubber inner ring to minimize driveline vibration in addition to balancing.
Trunnion	One of four projecting journals of a cross.
Tubing	The tubular connecting member of a driveshaft.
Tube Diameter	The outside diameter of a tube.
Tube Yoke	A yoke with a piloting hub for attachment of a tube.
U-Bolt	A clamping bolt with two parallel threaded legs used to retain a round bearing in certain end yoke designs.
Universal Joint	A device which can transmit torque and/or rotary motion from one shaft to another at fixed or varying angles of intersection of the shaft areas.
Wall Thickness	The measurement between the inside and outside diameter of a tube.
Weld Yoke	Same as tube yoke.
Wing Bearing	A member with a key and projecting wings used as the bearing base and positioning the thrust end of a cross trunnion.
Yoke Shaft	A one piece member designed to incorporate a tube yoke, tubing and stub shaft. It is used in close-couple applications and eliminates the need to use tubing.
Zerk	A lubrication fitting, usually threaded into a driveline component that will allow grease to be injected into the component, but does not allow grease to escape.