Patent ID: 6776268
Filing Date: 2004-08-17
Classification: B60T

Abstract:
Unitized brake equipment for a railcar comprising:a. a brake cylinder; b. a single piston having a piston head end movably housed in said brake cylinder and a piston rod end connectable to a brake member for applying braking force on said railcar; c. a first volume communicating on at least a portion of a first side of said piston head, pressurization of said first volume causing said single piston to move in a first direction to increase braking force on said railcar; d. a second volume communicating on at least a portion of a second side of said piston head, pressurization of said second volume tending to cause said single piston to move in a second direction to decrease braking force on said railcar; and e. a control valve portion controllable responsive to an electrical brake signal selectively coupling at least one of said first and second volumes with at least one of each other, a source of pressure, and the atmosphere to control pressure in said first and second volumes and move said single piston to control braking force on said railcar in a graduable manner; f. a third volume connectable via said a control valve portion to at least one of said first volume, said second volume, and said source of pressure; g. wherein said control valve portion further comprises a valve between said second volume and the atmosphere, and a piston travel interlock valve between said valve and atmosphere, said piston travel interlock valve movable between first and second positions responsive to travel of said single piston, said piston travel interlock valve isolating said second volume from said valve in said first position and connecting said second volume to said valve in said second position, said second position corresponding to a predetermined amount of travel of said single piston in said first direction.