Abstract: The trolley pole is mounted on a cylindrical bearing member secured to the side of an electric mule or locomotive for pivotal movement about a vertical axis. A latch mechanism provides a segmental plate horizontally disposed acentrically of said cylindrical bearing member for movement with it so as to turn in a horizontal path when the trolley pole and its mounting cylinder are turned, and a latch assembly adjacent said path fixed to a contiguous portion of the locomotive housing having a horizontally pivoted detent that normally rests with its free end within the path of the segmental plate in registration with the latter so as to lock the plate and its associated cylindrical mount and trolley pole in one selected position.