The single joints transfer the initiated uniform motion non-uniformly, because in one revolution of the driving shaft the driven shaft is accelerated twice and slowed down twice. The size of the cyclic irregularity depends on the working angle ß.
To keep the motion uniform, two single joints (or one drive shaft) or one double universal joint must be used. If minor irregularities in rotation are acceptable or the working angles are only small, just one joint may also be used.
The working angle ß must be equal at each end of the intermediate shaft for uniform transmission of motion.
Improperly assembled drive shafts reinforce the irregularities of the rotary motion instead of compensating for them. This may destroy the joint bearings and splines. For this reason, the marks on the splined shaft and the socket must be in line when assembling the two halves of the drive shaft.
It is also important for the bearings to be installed as close as possible to the drive shafts.
Proper lubrication of drive shafts in friction bearings is essential for sustained operation. If drip-feed lubrication is not possible, the joints should be greased once a day. The joint may also be covered with a GN 808.1 protective boot which is filled with oil or grease.