A shaft and B angled shaft are coupled by a universal joint, and in case that driven shaft I rotates with some constant angle speed, non-driven shaft II rotates inconstant angle speed.
Such an inconstant angle speed is called as “CARDAN ERROR”. If rotating angle of driven shaft I is shown as “a” and angle of joint as “b”, there is a relation as below, between shaft I and shaft II, “w1” and “w2”.
Minimum angle speed ω2 min=cos β ω1,w1 is repeated at the ratio of 1 cycle 1 – 2times.
However such an inconstancy with one joint can be offset by connection of 2 universal joints in a row.