At movement of mechanical system the sum of works of all operating forces on some moving is equal to change of its kinetic energy T, i.e.:

where and value of kinetic energy in initial and final positions of system.

For  our considered task:

i.e., kinetic energy of all system in initial and final positions is equal to zero.

Hence, the force developed by system of mobile elements, does not make work.

 

 

The system of mobile elements for the working period changes the kinetic energy  in an interval:

(39)

 

Increase of kinetic energy is a translation of system of mobile elements in a working condition.

Decrease of kinetic energy a stop of mobile elements during a running cycle.

From this interval we shall define work on moving mobile elements:

(40)

 

 

The capacity developed by system of mobile elements for the working period:

 

(41)

 

The note:

Values of work and capacity are found from a condition, that elements of mobile system completely stop after end of a running cycle. In real devices it to do it is inexpedient. It is desirable to change speed of mobile elements only on one coordinate.

In that case, it is possible to use a stock of kinetic energy of mobile system for translation of the FE in a working condition. Thus values (40) and (41) will be much less.