Functional principle

The functional principle

Safety “Made by Gelbau”

The closing edge safety system consists of a one piece extruded rubber profile as the sensor element and the evaluation electronics. The switching chamber of the rubber profile contains either two or four electrically conductive, mutually insulated rubber layers with integrated copper wire which serve as the switching surface. The connected evaluation electronics constantly monitors the closed circuit current.


When the switching strip is operated by mechanical pressure, the switching surfaces inside will touch each other. The chance in resistance value is detected by the evaluation electronics and the movement of the gate, door or machine part immediately stopped. Whether it’s a roller gate for a logistics warehouse, a lifting platform for the municipal theatre or a protective feature for a press – the Contact-Duo and Contact-Optima-Profile performs its duties reliably whenever shear and pinch edges constitute a safety problem. With its action range of 360°, the Quadro-Profile is used primarily as a safety feature for the closing edges of passenger doors on busses and trains.


For a functioning system, you need not only the profile and the evaluator unit, but also a terminating plug connector, which serves as an electrical termination. A plug connector with cable constitutes the link between the profile and the evaluator unit. In addition, the ends have to be closed off with end caps. With the Contact-Optima-Profile the end caps are installed only to close off the compensation chamber. For the Quadro-Profile, you also use a flexible wire jumper in addition to these components.


A flexible copper wire has been permanently extruded into the two parallel electrically conductive and mutually insulated rubber layers.

Mechanical pressure will trigger electrical contacting, which causes the potentialinsulated safety contact to open at the evaluator unit.