Patent ID: 6896339
Filing Date: 2005-05-24
Classification: B60T

Abstract:
1. A pneumatic braking system for a vehicle comprising: a brake cylinder; a reservoir; a brake pipe; a latching exhaust valve (LEV) movable between an open state and a closed state fluidly connected between the reservoir and the brake cylinder, said LEV comprising a first solenoid comprising a first pilot fluidly connected to said reservoir and a second solenoid comprising a second pilot fluidly connected to said reservoir; said pilots configured to be controlled electronically, said pilots configured to be controlled pneumatically, the electronic or pneumatic control being selectable based on vehicle operating requirements, said solenoids configured to be piloted with pneumatic pressure from said reservoir; and an electronic controller comprising a release on failure circuit, said release on failure circuit comprising a complex programmable logic device (CPLD) configured to control said LEV during at least one of a loss of power to said braking system and a failure of said electronic controller, said release on failure circuit further configured to control said LEV such that pneumatic pressure in said brake cylinder is maintained if power to said system is lost and the pneumatic pressure in said brake pipe is below a specified threshold, said release on failure circuit further configured to control said LEV such that pneumatic pressure from said brake cylinder is exhausted if power to said system is lost and the pneumatic pressure in said brake pipe is above a specified threshold.