Abstract: A method for performing an “AND” operation on two independent inputs in a fail-safe manner includes cascading two charge pumps to output a condition signal representing the “AND'ed” state of the inputs. Each independent input has an active state asserted by a waveform of predetermined frequency and duty cycle, and an inactive fail-safe state asserted by a zero voltage. The method includes supplying power to a first charge pump, supplying power from the first charge pump to a second charge pump, and supplying each of the independent inputs to one of the respective charge pumps. A condition signal is output using an output from the second charge pump. Additionally, the method verifies the correctness of the frequency and duty cycle of each independent input using a cross connection scheme. This method provides a high-power, low-loss, and low-cost electrical circuit for operating devices responding to specific voltages, for example, vital relays.

Abstract: A railway car brake system includes a pneumatic brake cylinder and a relay valve for controlling pressure in the brake cylinder. The relay valve is responsive to a pilot pressure which is generated by a pilot valve connected to the relay valve, the pilot valve including at least one piezoelectric element. The system also includes a controller connected to the piezoelectric element to control the pilot pressure and thereby control braking. The pilot valve releases braking upon loss of power to the at least one piezoelectric element to thereby provide a failsafe release of braking. The pilot valve may also include a first piezoelectric element for controlling fluid flow from a pressure source to the relay valve, and a second piezoelectric element for controlling fluid flow from the relay valve to atmosphere.

Abstract: A system and method for dynamically controlling the operation of a plurality of unmanned freight trains operating over a predetermined track layout. The method includes generating a movement plan that provides for the operation of the freight trains over several alternative routes within the track layout. A wireless communication system is used to transmit speed and braking commands to the freight trains. Commands for the wayside resources are transmitted, using wireless communications, as necessary to carry out the movement plan.

Abstract: This invention relates to a system and method of detecting a broken rail in a railway system. The track sensing circuitry of the present invention applies a voltage source at each end of a block of rails and senses the current flowing through the circuitry. The present invention will detect broken rails continuously in a block, even with a train present (except for a break directly beneath the train). Since the rail is continuously checked, the only restriction imposed on train spacing by this track circuit configuration is that only one train can be present in a block at a time.