Mechanical system

 A mechanical system manages power to accomplish a task that involves forces and movement.
   A mechanical system consists of (i) a power source and actuators that generate forces and movement, 
                                                 (ii) a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement, and  
                                                 (iii) a controller with sensors that compares the output to a performance goal and then directs the actuator input. 
    This can be seen in Watt's steam engine (see the illustration) in which the power is provided by steam expanding to drive the piston. The walking beam, coupler and crank transform the linear movement of the piston into rotation of the output pulley. Finally, the pulley rotation drives the fly ball governor which controls the valve for the steam input to the piston cylinder.
     A Mechanical System Shown Below: