Relais mit stufenweise betaetigtem Anker

511,563. Automatic exchange systems. TELEFONAKTIEBOLAGET L. M. ERICSSON. Sept. 30, 1938, No. 28495. Convention date, Nov. 27, 1937. [Class 40 (iv)] [Also in Group XXXVII] In a two-step relay particularly for use in telephone circuits as a combined line and cutoff relay wherein the successive energization of two windings A, B causes an armature 11 to move to its fully attracted position in two steps, movement from rest to the first step causes the engagement of contact springs 5, 7, movement from first step to second step causes the shifting of a latching member 2, return movement from the second step to the first causes the separation of contacts 5, 7 and movement back to rest restores all parts to their original position. In the form shown in Fig. 1, the armature 11 engages a projection 10 on the spring 5 causing the spring 5 to engage the spring 7. During the second step the springs 5 and 7 move up together and the latch 2 under the action of a spring 4 moves to a vertical position in which a portion 8 comes beneath a projection 8. During the first half of the return movement therefore, when the contact 5 is allowed to move down, the contact 7 is retained in its uppermost position. During the'last half of the return movement, a projection 9 moves the latch 2 back to its original position. There are numerous modifications described but in all of them circuit is made during the first step and broken during the first portion of the return movement. Other contact springs are actuated simultaneously. Fig. 4 shows a subscriber's line circuit. Upon receipt of an incoming call winding A will be energized closing contact 5 and energizing a relay C which then starts the call finders over the contact 30. Owing to the high resistance of C, winding B cannot operate the relay through its second step until the calling line has been found whereupon relay moves through its second step and opens contacts 31, 32, 33. If the connection is then released while the receiver is still removed or if there is a permanent loop, winding B will be de-energized but A will remain energized, the armature being now in its intermediate position with the contact 5 open. This ensures that no other call can be initiated.