As explained under 2.1, on a single joint the output velocity deviates from the input velocity. This means, the speed ratio is not uniform. This non-uniformity (fluctuation) can be calculated as a dimensionless value:

Fluctation rate

If the preconditions listed in Chapter 1 for obtaining a complete motion compensation cannot be met, it must be aimed for that: U <= 0,0027.

Design requirements might dictate the use of a universal driveline that employs more than 2 joints. This universal driveline, how-ever, must then incorporate an intermediate bearing.
Here, also, the condition applies:
Uges <= 0,0027.
Here, URes expresses the total fluctuationof the driveline.
Observe, when determining URes:
a) Joints with the same fork position get the same sign.
b) The fluctuation rate of each joint must be calculated individually U1, U2, U3.
c) c) The signs must be observed when adding:

Since the rate of fluctuation is a function ofdeflection angle ß, a limiting condition canbe set in regard to the resulting deflectionangle ßres

ßres corresponds to the deflection angle ofa single joint
if it were to replace the entiredriveline.