Methods and system for controlling latching exhaust valves

摘要

A pneumatic braking method and system for a vehicle is provided. The system includes a brake cylinder, a reservoir, a latching exhaust valve (LEV) movable between an open position and closed position and fluidly connected between the reservoir and the brake cylinder. The LEV includes a first solenoid having a first pilot fluidly connected to the reservoir and a second solenoid having a second pilot fluidly connected to the reservoir wherein the pilots are configured to be controlled electronically and pneumatically, said selectable between electronic and pneumatic control based on the vehicle operating requirements. The solenoids are configured to be piloted with pneumatic pressure from the reservoir and an electronic controller that includes a release on failure circuit. The release on failure circuit is configured to control the LEV during at least one of a loss of power to the braking system and a failure of the electronic controller.