The diagram shows typical loads applied to a shaft during power transmission and the resultant deflections (assumed to be small for the purposes of this guide). Not all the loads shown will be present in every case.

Torsional loads: due to the torque being transmitted

Transverse loads: applied by many transmission elements (eg: belts)

Axial loads: result from the use of some transmission elements (eg: helical and worm gears)

Twist: due to torsional load