Transfer system of work machine, work machine, and method of predicting lifetime of transfer system in work machine

A transfer system of a work machine comprising:

• a drive source;
• a first clutch including a first member that rotates by receiving motive power from the drive source and a second member switched between an engaged state in which the second member is engaged with the first member and a disengaged state in which the second member is not engaged with the first member;
• and
• a controller that calculates a coefficient of friction between the first member and the second member based on a time period elapsed from a first time point when a number of relative rotations of the first member and the second member attains to a first number of rotations to a second time point when a second number of rotations smaller than the first number of rotations is attained, in a state in which transfer of motive power from the drive source to the first member that is rotating is cut off and in the engaged state.