Signal,28480-8640b-001-002-003 ser 2708a and up end item identification

An_electromagnetically_actuated_switch_having_contact_wipers_which_are_successively_rotated_over_fixed_bank_contacts._the_contact_wipers_are_progressively_advanced_over_the_fixed_bank_contacts_through_a_repetitive_series_of_stepping_operations._the_stepping_operation_may_be_a_continuous_forward_rotation_acting_through_360_degrees_to_return_to_its_normal_unoperated_position_or_it_may_be_designed_to_include_an_electromagnetic_and/or_mechanical_means_for_releasing_and_resetting_the_switch_to_its_released_position_for_a_subsequent_operation._the_contact_wipers_may_be_mechanically_held_in_contact_with_the_fixed_bank_contacts_after_the_armature_of_the_actuating_coil_has_released._the_switch_may_be_released_at_the_end_of_its_travel_or_at_any_intermediate_position._it_includes_items_designed_with_two_electromagnetic_actuators_that_enable_the_switch_to_operate_in_either_direction._for_items_having_the_dual_function_of_a_switch_and_a_relay_assembled_together_on_a_common_mounting,_see_relay-switch._for_other_than_electromagnetically_actuated_switches_whose_contact wipers are manually rotated over fixed bank contacts, see switch, rotary. Excludes:relay, rotary and switch, telephone (as modified).