5. Additional moments on the drive line Bearing loads
on the in- and output shaft
5.2 Bearing loads on in- and output shaft with Z-arrangement
5.3 Bearing loads on in- and output shaft with W-arrangement
5.4 Caused by axial displacement forces
In Section 2.2 it was shown that the torque is being transmitted only in the spider plane and that depending on the fork position, the spider can be perpendicular either to the input axis
or the output axis.
What additional forces and moments this causes on the driveline as well as on the bea-
rings of the in- and output shaft, is explained briefly in the following chapter.
The adjacent illustration shows the location and direction of the additional forces and moments on drivelines having a Z-arrangement, in particular for yoke angles j1 = 0° and j1 = 90°. This shows clearly, that the driveline center part is stressed by the torque which fluctuates between MdI · cos ß and MdI/ cos ß in torsion and by the additional moment MZII periodically alternating, in bending. (See also Section 6.8).
Likewise, in- and output shaft are stressed by MZI and MZIII periodically alternating in bending. The resulting bearing load A and B vary twice per revolution between O and maximum value.
Driveline-center part stressed in bending
Driveline-center part stressed in bending
According to the adjacent illustration, with the W-arrangement, an additional force, “S“ is introduced,
caused by the additional moments MZII acting in the same direction. The maximum force value occurs at fork position
j1 = 0° , and it is being transmitted to the input- and output shaft by the faces of
the spider pins.
In- and output shaft stressed in bending
In- and output shaft stressed in bending
If a driveline with an adjustable spline is being changed in length while under torque, in both cases, Z- or W configuration, addition bearing loads are introduced, resulting from the friction caused in the spline. The axial displacement force Pa responsible for these bearing loads is calculated as follows:
dm is the spline pitch diameter, Ü the spline overlap. Depending on configuration and lubrication, the coefficient of friction for steel on
steel must be assumed to range from 0.11 to 0.15. Plastic coated splines have considerably better sliding characteristics. Here, the friction value is approximately 0.08. Rilsan coated splines are available from size 0.109 up.
