are three common types of U-joint designs.
Single U-joints retained by either an inside or outside snap ring.
Coupled U-joints commonly called the double-Cardan constant velocity joints.
U-joints held in the yoke by U-bolts or lock plates.
Single Universal Joint
single Cardan/Spicer universal joint is also known as the cross or four-point
joint. These two names aptly describe the single Cardan, since the joint itself
forms a cross, with four machined trunnions or points equally spaced around the
center of the axis. Needle bearings used to abate friction and provide smoother
operation are set in bearing cups. The trunnions of the cross fit into the cup
assemblies and the cup assemblies fit snugly into the driving and driven
universal joint yokes. Universal joint movement takes place between the
trunnions, needle bearings, and bearing cups. No movement should take place
between the bearing cup and the hole in the universal joint yoke. The fit
between the hole in the yoke and the bearing cups is known as a press-fit.
Retaining rings hold the bearing cups in place in the universal joint yoke.
Replacing a single U-joint requires that the technician know more than the make
and model of the vehicle. It might be necessary to know the type of U-joint and
the yoke span to obtain the proper replacement part.
Spicer Style In this angle U-joint design an outside snap ring fits into a
groove machined in the outer end of the yoke. The bearing cups for this style
are machined to accommodate the snap ring.
Mechanics or Detroit/Saginaw Style In this design, an inside snap ring or
C-clip fits into a groove machined in the bearing cup on the side closer to the
grease seal. When installed, the clip rests against the machined inside portion
of the yoke. The snap ring in the Detroit/Saginaw style is injected nylon. That
is, the snap rings are retained by nylon injected into the retaining ring
Cleveland Style In an attempt to combine U-joints to obtain more coverage,
the Cleveland style is used for some applications. The bearing cups for this
U-joint are machined to accommodate either Spicer or Mechanics style snap rings.
If a replacement U-joint comes with both style clips, use the clips that pertain
to your application.
Double-Cardan Universal Joint
often installed in front-engine rear-wheel-drive luxury automobiles, the double-Cardan
universal joint smoothly transmit torque regardless of the operating angle of
the driving and driven members. It is, therefore, classified as a constant
velocity universal joint. Observe the left and right universal joint
centerlines. The bisect the angle made by the input driving and the output
driven universal joint. Constant velocity operation is the result.
double-Cardan universal joint is made up of two Cardan universal joints linked
together by a coupling yoke. A centering ball socket is inside the coupling yoke
between the two universal joints. This ball and socket maintain an axial
relationship between the two universal joints. The ball joint divides the
universal joint operating angle into two equal parts, so each universal joint
operates at half of the operating angle. Since the two universal joints operate
at the same angle, vibrations and fluctuations in speed from the front joint are
nullified by the vibrations and fluctuations in speed from the rear universal
joint. The canceling angles produce a smooth transfer of engine torque. The
double-Cardan joint is often a vital part of a two-piece drive axle shaft.