When it is a specific case of pressure reaching a minimum value, the motor must act by turning it back on. It is necessary to emphasize that the return of the drive contact in the electric motors is carried out automatically by means of a spring. There are also one-touch pushbuttons, which may be of the normally open type, NA, or normally closed, NF. https://www.mrosupply.com/electrical/circuit-protection-and-distribution/power-meters-power-supplies-solar-transformers/phase-converters/5054062_pam-300hd_phase-a-matic/ The control buttons are identified according to the standards specified by the machine manufacturer.

Therefore, when the manual button is replaced by a roller, the limit switch can be found, which is normally used in pneumatic and hydraulic circuits, and is widely used in the movement of loads, driven in the stop of a crate, crate, or any other type of cargo.

Other types of signal elements are thermostats, pressure switches, level switches and limit switches, which can be rollers, for example.

All these elements exert a control action considered subtle, that is, it does the on and off function. To illustrate, in case the pressure of a system reaches a limit value, the action of the pressure switch will basically be to move the contacts off the system.