This part of ISO 5673 specifies the power take-off (PTO) drive shafts of a tractor or self-propelled machine used in agriculture and the power-input connection (PIC) of its implement, establishing a method for determining PTO static and dynamic torsional strength while giving manufacturing and safety requirements. It is applicable only to those PTO drive shafts and guards mechanically linked to the shaft by at least two bearings. It is not applicable to PTO drive shafts guarded by location or to the mechanical characteristics of overrun devices and torque limiters, nor are environmental aspects considered; neither is it applicable to PTO drive shafts and their guards manufactured before the date of its publication.