for increasing the reliability of contact closure in safety relays , a contact spring is provided with two contact pieces which are disposed at the free end of the contact spring , spaced transversely of the longitudinal axis thereof and cooperate with contact pieces disposed on a common fixed contact . the contact spring has a zone in which it is not only flexible but also sufficiently torsional about its longitudinal axis in order to ensure the closure of both contact couples . disposing the free end of the contact spring carrying the contact pieces at an angle with respect to the fixed contact achieves smooth and low - bounce contact closure and at the same time provides the function of a pre - contact and a main contact .