Abstract: A solenoid is provided which, in the preferred embodiment, has a bobbin having an axial opening in it. A divider is mounted within the opening. Respective ones of a first pole piece and a second pole piece are located on opposite sides of the divider. A permanent magnet is moveably mounted from the axial opening and is moveable independently of the second pole piece between at least a first position adjacent to the divider, and a second position adjacent the second pole piece. The construction provides a fast acting, low cost latching solenoid construction.

Abstract: A shutoff and exhaust valve for tractor-trailer air brake systems operates to open or close communication between the tractor and trailer service lines in accordance with the pressure in the tractor emergency line and the trailer service line is exhausted to atmosphere through the same valve.