What is the primary method for precise positioning of pistons in air cylinders?

The primary method for achieving precise positioning of pistons in air cylinders typically involves utilizing mechanical stops as these provide a fixed, reliable means of limiting the cylinder's travel. Mechanical stops physically restrict the movement of the piston, ensuring that it reaches or maintains a desired position without reliance solely on variable factors like air pressure or other system controls.

While electronically controlling the direction or stop of the pistons can be effective, relying solely on a solenoid or directional control valve (as suggested in one of the choices) does not guarantee precision because the system may experience factors such as air compressibility and system inertia. Reducing air pressure can affect the force output of the cylinder but does not inherently provide the precision needed for accurate positioning. Moreover, stating that precise positioning cannot be done undermines the various mechanisms in place, such as mechanical stops, that facilitate this function in pneumatic systems.