The invention relates to a system (400) comprising a vehicle (402), an arm assembly (408), first and second cable portions (410a, 410b), at least one cable actuator (406), and an air supply line. The vehicle has a pneumatic source of pressurized air. The arm assembly has an end effector releasably coupled to an end of an axially-extendable arm coupled to the vehicle. The end effector has a gladhand coupling portion. The air supply line can be coupled to the end effector and can deliver pressurized air from the pneumatic source to a braking system of the trailer when the gladhand coupling portion is coupled to the gladhand receptacle of a trailer. After coupling to the gladhand receptacle, the end effector can be disconnected from the arm assembly to allow the remainder of the arm assembly to be stowed.