Universal Joints and Driveshafts H.Chr.Seherr-Thoss · F ... - Index of

26 1 Universal Jointed Driveshafts for Transmitting Rotational Movements
the tracks is undefined [2.9, p. 47] and the joints cannot function at articulation
angles less than about 18°. Hence in 1933 Rzeppa introduced the “pilot lever” as an
auxiliary control device (Fig. 1.23b). However with wear the auxiliary steering fails
and the balls jam and so in about 1960 these joints were superseded by joints with
track steering.
The cage is extended spherically. The lever with two outer balls and a centre ball
is located in three places: in the joint shaft, in the spherical extension and in the inside
part of the joint. The spacing of the three balls is chosen so that, when the joint
articulates, the cage puts the balls into the plane of symmetry p. With this steering
system the full track depth is maintained which gives a high transmission capacity.
With increasing wear however, this auxiliary steering fails and the balls jam.
In 1933 Rzeppa also suggested the use of saucer-shaped rings as a mean of auxiliary
steering (Fig. 1.29). The spherical surfaces S and T with generating radii r a and
r i steer the cage, together with balls, into the plane of symmetry p, implementing the
offset principle once more.
Further steering devices or combinations of the various types of steering are
feasible.
From 1934/39 Rzeppa provided for the tracks of the outer joint body to be
undercut free; they followed straight lines inclined to the axis and they diverged
from one another towards one side and could only be incorporated from there
into the joint body (US Patent 20 46 584).With this design, however, it was no longer
possible to achieve an adequate track depth at large articulation angles so that there
a
b
Fig. 1.29a, b. Auxiliary steering of the ball cage into the constant velocity plane according to
Alfred H. Rzeppa 1933 using saucer-shaped rings which amounts to the offset-principle (US
patent 2010899 and German patent 624463). a Rings S and T, b joint. The rings S and T rotate
about their centres O 1 and O 2 which are displaced by the same amount c from the joint centre
O. Ring T slides on the spherical face R of the outer body and on the spherical face S which is
joined to the inner race. Thus the centre O 1 of the hemisphere R is raised during articulation,
while O 2 remains stationary. The line O¢ 1O 2 steers the cage, with the balls, into the plane of
symmetry p again according to the offset-principle