The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 15, 1992
Filed:
Sep. 21, 1990
Forrest H Ballinger, Grain Valley, MO (US);
Harmon Industries, Inc., Blue Springs, MO (US);
Abstract
A reliable and consistent electrical contact path between the rails of a railroad track established by the shunting effect of the wheels and axles of a train is ensured by applying an alternating current signal to the rails at a voltage level sufficient to overcome poor wheel/rail contact and cause a wetting current to flow between the rails. This likewise provides a current path for railroad control and communication signals, such as the island circuit signal of a grade crossing warning system. The effective range of the wetting current signal is limited by providing the signal with a frequency of 10 KHz or higher to inductively isolate the signal source and associated stretch of track from any shunts beyond that stretch. To avoid interference with other types of electronic track equipment, the signal is applied only when required. In grade crossing warning systems, it is controlled in a fail-safe manner.