Movable or removable closures – With traffic director or controller; e.g. – one-way
Reexamination Certificate
2000-08-17
2001-12-11
Redman, Jerry (Department: 3634)
Movable or removable closures
With traffic director or controller; e.g., one-way
Reexamination Certificate
active
06327818
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to an improved gate device for preventing pedestrians and vehicular traffic from crossing railroad grades. Specifically, the present invention relates to gate devices that protect lowered railroad crossing gate arms from damage.
BACKGROUND OF THE INVENTION
Railroad crossing gate arms are lowered from a vertical position to a horizontal position to block traffic from crossing railroad tracks when a train is present. When lowered to their horizontal position, gate arms can suffer damage from passing vehicles, wind pressure and vandalism. Damage frequently results in broken gate arms that sever at their point of attachment to a crossing gate mechanism. Such damage risks exposing pedestrians and vehicular traffic to improperly guarded train crossings. To maintain safety and the integrity of grade crossing equipment, railroads expend substantial resources monitoring, repairing and replacing damaged crossing gates. Thus, in the first instance, it is advantageous to protect lowered gate arms from damage.
Various methods of protecting gate arms from damage were known to the prior art. Employing camblocks and ball bearings, U.S. Pat. No. 4,897,960 issued to Barvinek, et al., (hereinafter referred to as “Barvinek”) describes a mechanism designed to provide flexibility to lowered gate arms. Barvinek discloses a housing for pivotally mounting a support tube that swings a partially translucent, internally illuminated, impact-resistant gate arm away from an applied force. A camblock is mounted inside the housing, allowing the gate arm support tube, having a pair of ball bearings retained within, to rotate around a retaining pin that extends upwardly through the center of the camblock when force from a passing vehicle is applied. Downward force on the rotating gate arm support tube, applied by a coil spring mounted on the retaining pin, forces the arm to return to its original position parallel with the groove of the camblock when the force dissipates. However, Barvinek suffers from numerous problems. Relying on camblocks and ball bearings, Barvinek is expensive to manufacture, monitor and maintain. Moreover, Barvinek cannot return a displaced gate arm to a position parallel with the groove of the camblock if the gate mechanism rises while the gate is displaced. Finally, Barvinek provides no control over the rate of gate arm return and cannot prevent gate arm over travel into the flow of traffic.
Alternatively, U.S. Pat. No. 5,469,660, issued to Tamenne, (hereinafter referred to as “Tamenne”) employs a spring and hydraulic piston system. Tamenne discloses a pivot assembly allowing a lowered gate arm to rotate away from traffic when a passing vehicle applies pressure and then to return to its original position once pressure is removed. The pivot assembly is mounted on a counter-weighted gate arm mechanism and includes springs mounted on a shuttle post assembly to return the gate arm to a position perpendicular to the flow of traffic. The pivot assembly includes a hydraulic piston to buffer the rate of gate arm return and a weight channel to counterbalance the gate mechanism's main counterweight when the gate arm is rotated away from passing traffic. However, Tamenne also suffers from numerous problems. Tamenne's hydraulic piston system, like Barvinek's camblock and ball bearing system, is expensive to manufacture, monitor and maintain. Further, Tamenne's weight channel counterbalance places an imbalanced strain on the gate arm pivot assembly, risking damage to the gate arm mechanism. Tamenne also decreases safety at crossing grades when the gate arm is displaced, because the weight channel swings from a position generally parallel with the flow of traffic to a position generally perpendicular to the flow of traffic and through an area where pedestrians may be standing. Like Bamivek, Tamenne is incapable of returning a displaced gate arm back to its normal position if the gate mechanism rises while the gate is displaced.
Therefore, a need exists for a crossing gate mechanism that can rotate a crossing gate arm out of the way of a damaging force while safely and efficiently returning the gate to its normal position, that is capable of being adjusted for installation in conditions requiring varied gate arm lengths and flexibilities, that is capable of preventing excessive impact when the gate arm returns to its normal position, that prevents gate arm over travel upon return from a displaced position, that is capable of being adjusted for varying gate arm return force requirements, that is less expensive than existing spring-based crossing guard mechanisms, and that is not subject to the potential for deterioration of a cam-and-bearing based crossing gate mechanisms.
SUMMARY OF THE INVENTION
The present invention provides a crossing gate mechanism for use in a railroad crossing gate. In one embodiment, the crossing gate mechanism includes a gate arm adapter for receiving the gate arm and allowing rotation of the gate arm away from a normal operating position approximately perpendicular to a flow of traffic upon application of a displacement force. The gate arm adapter is capable of being pivotally mounted to a vertical support structure to allow the rotation of the gate arm. A return force mechanism coupled to the gate arm adapter provides for a return of a displaced gate arm adapter to the normal operating position upon removal of the displacement force. In the one embodiment, the crossing gate mechanism further includes a latch hook assembly that holds the gate arm adapter in its normal operating position in the absence of a displacement force. In another embodiment, the crossing gate mechanism further includes a drag brake that retards a rate of return of the gate arm adapter to the normal operating position from a displaced position upon removal of the displacement force.
In another embodiment, the crossing gate mechanism includes a crossing gate arm, the gate arm adapter, and a return force mechanism attachment point. The gate arm adapter receives the crossing gate arm and includes a hinge pin that allows rotation of the gate arm away from the normal operating position upon application of the displacement force. The return force mechanism attachment point is diametrically opposite the hinge pin from the gate arm, and the return force mechanism attachment point, the hinge pin, and the gate arm are disposed in a generally linear relationship.
In another embodiment, the crossing gate mechanism includes a latch hook assembly. The latch hook assembly includes a pivotally levered latch that selectively restrains the gate arm adapter in its normal operating position, and a latch hook pressure mechanism that applies a leveraging force to the pivotally mounted latch to produce a pivotally levered force of the latch. The latch hook assembly further includes a hook and drag surface that receives the pivotally levered force of the latch upon application of a displacement force to the crossing gate mechanism.
REFERENCES:
patent: 873162 (1907-12-01), McGladdery et al.
patent: 1628651 (1927-05-01), Burress
patent: 2295419 (1942-09-01), Miskelly
patent: 2826840 (1958-03-01), Cooper et al.
patent: 4124955 (1978-11-01), Kochis
patent: 4364200 (1982-12-01), Cobb
patent: 4897960 (1990-02-01), Barvinek et al.
patent: 5469660 (1995-11-01), Tamenne
patent: 5653058 (1997-08-01), Zaimins
patent: 449464 (1991-10-01), None
patent: 2231844 (1974-12-01), None
Banner & Witcoff , Ltd.
Redman Jerry
Western-Cullen-Hayes Inc.
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