Patent Description:
Warning systems have been developed to warn people and cars of an approaching train at a railroad grade crossing. Railroad grade crossings, sometimes referred to as level crossings, are locations at which railroad tracks intersect roads. A constant warning time device, also referred to as a grade crossing predictor (GCP) or a level crossing predictor, is an electronic device that is connected to the rails of a railroad track and is configured to detect the presence of an approaching train and determine its speed and distance from a railroad grade crossing. The constant warning time device, in combination with a crossing controller, will use this information to generate constant warning time signal(s) for controlling crossing warning device(s).

Crossing warning devices are devices that warn of the approach of a train at a crossing, examples of which include crossing gate arms (e.g., the familiar red and white striped wooden, fiberglass or aluminum arms often found at highway grade crossings to warn motorists of an approaching train), crossing lights (such as the red flashing lights often found at highway grade crossings in conjunction with the crossing gate arms), and/or crossing bells or other audio alarm devices. A crossing gate serves as a barrier across a highway when a train is approaching or occupying a crossing. The crossing gate is typically combined with a standard flashing light signal that provides additional warning before the arm starts to descend, while the gate arm is across the highway, and until the gate arm ascends to clearance. A gate mechanism contains mechanical and electrical devices to control the gate. The gate mechanism is either supported on the same post with the flashing light signal or separately mounted on a pedestal adjacent to the flashing light signal post.

Existing crossing gate mechanisms can be tampered with by having a pedestrian lift the gate arm(s). Lifting the gate arm(s) removes the physical barrier between the public and the rail crossing, and therefore creates an unsafe condition. This is most prevalent where there is a sidewalk arm present and due to gearing within a mechanism if a pedestrian lifts a sidewalk barrier the primary vehicle barrier will lift as well. This gives the appearance that the crossing is open/opening to vehicle traffic and is therefore unsafe.

Existing crossing gate mechanisms are described in document <CIT> or in <NPL>.

Briefly described, the present invention provides a gate mechanism, specifically a tamperproof gate mechanism utilized for example in railroad crossing gate applications.

A first aspect of the present disclosure provides a linkage operably coupled to a crossing gate arm, wherein the crossing gate arm is movable between a vertical position and a horizontal position via the linkage, wherein the linkage is in a first position when the crossing gate arm is in the vertical position and in a second position when the crossing gate arm is in the horizontal position, and wherein the linkage in the second position mechanically locks the crossing gate arm in the horizontal position.

A second aspect of the present provides a railroad crossing gate comprising a crossing gate arm, and a gate mechanism with a linkage operably coupled to the crossing gate arm, wherein the crossing gate arm is movable between a vertical position and a horizontal position via the linkage, wherein the linkage is in a first position when the crossing gate arm is in the vertical position and in a second position when the crossing gate arm is in the horizontal position, and wherein the linkage in the second position mechanically locks the crossing gate arm in the horizontal position.

To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments. In particular, they are described in the context of a gate mechanism, specifically a tamperproof gate mechanism utilized for example in railroad crossing gate applications.

The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present disclosure.

<FIG> illustrates an example railroad grade crossing <NUM>, also referred to as level crossing, in accordance with an exemplary embodiment of the present disclosure.

The railroad grade crossing <NUM> includes multiple railroad crossing warning devices, also referred to as grade crossing warning devices, which warn of an approach of a railroad vehicle, e.g. train, at the crossing of road <NUM> and railroad track <NUM>. The railroad crossing warning devices include for example a crossing gate arm <NUM> with (or without) gate arm lights <NUM> spaced along the arm <NUM>, crossing lights <NUM>, railroad crossbuck <NUM>, and/or other devices not illustrated herein, as for example crossing bells or other audio alarm devices. The crossing warning devices <NUM>, <NUM>, <NUM> are in communication with a constant warning time device <NUM>, also referred to as grade crossing predictor or GCP, via connecting elements <NUM>, which are for example electric cables. It should be noted that the components of <FIG> are illustrated schematically and are not drawn to scale, in particular are not drawn to scale in relation to each other.

The constant warning time device or GCP <NUM> is configured to detect the presence of an approaching train, determine its speed and distance from the railroad crossing, calculates when the train will arrive at the crossing, and uses this information to generate constant warning time signals for controlling the crossing warning devices <NUM>, <NUM>, <NUM>. Typically, a normally energized master relay <NUM>, only shown schematically herein, is arranged between the GCP <NUM> and the warning devices <NUM>, <NUM>, <NUM>, for example along the connecting elements <NUM> and operably coupled by the connecting elements <NUM>, wherein an output of the GCP <NUM> feeds a coil of the master relay <NUM>. According to a preprogrammed time, for example a number of seconds and/or minutes, before projected arrival time of the approaching train, the GCP <NUM> is configured such that the output feeding the coil of the master relay <NUM> is turned off to drop the master relay <NUM> and to activate the crossing warning devices <NUM>, <NUM>, <NUM>. It should be noted that the GCP <NUM>, the master relay <NUM> and the warning time devices <NUM>, <NUM>, <NUM> will not be described in further detail as those of ordinary skill in the art are familiar with these devices and systems.

<FIG> illustrates a simplified view of a railroad crossing gate application <NUM> with sidewalk arm in accordance with an exemplary embodiment of the present disclosure. The railroad crossing gate application <NUM> is a crossing warning device and can be located at a crossing <NUM> as illustrated in <FIG>, wherein the crossing warning device <NUM> can be configured as crossing gate <NUM>.

The railroad crossing gate <NUM> comprises a first crossing gate arm <NUM> and a second crossing gate arm <NUM> which serve as barriers across a road or highway or sidewalk when a railroad vehicle, e.g. train, is approaching or occupying a crossing. The first crossing gate arm <NUM> can be configured as vehicle arm for roads, highways etc., and the second crossing gate arm <NUM> can be configured as pedestrian arm for sidewalks, or vice versa. It should be noted that the vehicle arm <NUM> is typically longer than the pedestrian arm <NUM>. The gate arms <NUM>, <NUM> may comprise gate arm lights spaced along the arms <NUM>, <NUM>.

The railroad crossing gate <NUM> further comprises a gate mechanism <NUM> for operating the crossing gate arms <NUM>, <NUM>. Such mechanisms <NUM> comprise for example a gear train in combination with an electric motor for moving the gate arms <NUM>, <NUM> from a vertical position (when the gates are open) to a horizontal position (when the gates are closed). Direction of movement of the gate arms <NUM>, <NUM> is illustrated by arrows <NUM>.

Existing gate mechanisms, such as mechanism <NUM>, can be tampered with by having a pedestrian lift the pedestrian gate arm <NUM> (or the vehicle arm <NUM>). Lifting the gate arm(s) <NUM>, <NUM> removes the physical barrier between the public and the grade crossing, and therefore creates an unsafe condition. This is most prevalent where there is a sidewalk arm present and due to gearing within the mechanism if a pedestrian lifts a sidewalk barrier the primary vehicle barrier will lift as well. This gives the appearance that the crossing is open or opening to vehicle traffic and is therefore unsafe.

<FIG> illustrate multiple front views of a crossing gate mechanism <NUM> in accordance with exemplary embodiments of the present disclosure.

<FIG> illustrates crossing gate arm <NUM> in a vertical position VP, where the crossing gate arm <NUM> is lifted and pedestrians and/or vehicles can cross railroad track(s).

<FIG> illustrate intermediate positions of the crossing gate arm <NUM>, where the gate arm <NUM> moves from the vertical position VP to the horizontal position HP or vice versa. <FIG> illustrates the crossing gate <NUM> in the horizontal position HP, where the gate arm <NUM> is descended and pedestrians and vehicles cannot cross the railroad track(s). It should be noted that the components of <FIG> are illustrated schematically and are not drawn to scale, in particular are not drawn to scale in relation to each other.

In an exemplary embodiment, the crossing gate mechanism <NUM> comprises a linkage <NUM> including gear <NUM>. The linkage <NUM> is operably coupled to a crossing gate arm <NUM>. In our example, only the crossing gate arm <NUM> is shown, but the gate mechanism <NUM> may be configured to be coupled to and operate more than one crossing gate arm <NUM>, for example two crossing gate arms, as illustrated for example in <FIG>.

The crossing gate arm <NUM> is movable between a vertical position VP, illustrated in <FIG>, and a horizontal position HP, illustrated in <FIG>, via the linkage <NUM>. The linkage <NUM> is in a first position when the crossing gate arm <NUM> is in the vertical position VP, and the linkage <NUM> is in a second position when the crossing gate arm <NUM> is in the horizontal position HP. The linkage <NUM> in the second position mechanically locks the crossing gate arm <NUM> in the horizontal position HP as illustrated for example in <FIG>. By mechanically locking the crossing gate arm <NUM> in the horizontal position, the gate arm <NUM> cannot be manually lifted, for example by a pedestrian, which increases safety for pedestrians and vehicles at a grade crossing.

The linkage <NUM> comprises an over-center linkage. In particular, the gear <NUM> of the linkage <NUM>, when in operation, rotates over-center when the crossing gate arm <NUM> moves from the vertical position VP to the horizontal position HP. The direction of rotation of the gear <NUM> is illustrated by arrow R.

In an example, the linkage <NUM> comprises multiple components, such as for example a first connecting member <NUM> rotatably coupled at a first end to the crossing gate arm <NUM>, and a second connecting member <NUM> rotatably coupled at a first end to the gear <NUM>. The first and second connecting members <NUM>, <NUM> are rotatably coupled to each other at their respective second ends. The linkage <NUM> comprises a third connecting member <NUM> which provides stability and support for the first and second connecting members <NUM>, <NUM>. The third connecting member <NUM> is rotatably coupled to a stationary part of the mechanism <NUM>, such as for example a housing <NUM>, and further coupled to the connecting point where the second ends of the first and second connecting members <NUM>, <NUM> are coupled to each other.

The gear <NUM> is configured as segment gear and not as a full circular or round gear. For example, the gear <NUM> can be configured as half gear, wherein teeth of the gear <NUM> extend over a range of about <NUM>°. However, the segment gear <NUM> may comprise other configurations, for example may extend with teeth over a range of up to <NUM>°.

The crossing gate mechanism <NUM> further comprises housing <NUM>, wherein the linkage <NUM> is positioned in the housing <NUM>. A first structural element <NUM> and a second structural element <NUM> are arranged on an inner sidewall <NUM> of the housing <NUM>. The structural elements <NUM>, <NUM> can be fixed elements which serve as stopping point for the gear <NUM> and/or linkage <NUM>. In an example, the structural elements <NUM>, <NUM> are configured as spring buffers and each comprise for example a spring <NUM>, <NUM>. The second structural element <NUM> serves as stopping point for the gear <NUM>. The first structural element <NUM> provides a resting location for the linkage <NUM> in an unpowered descent of the crossing gate arm <NUM>.

In the first position of the linkage <NUM>, the gate arm <NUM> is in the vertical position VP (see <FIG>). The second connecting member <NUM>, which is coupled to the segment gear <NUM>, is not in a maximum stroke position which is considered "center". When the gear <NUM> rotates clockwise, as shown by arrow R, see <FIG>, the second connecting member <NUM> will reach the maximum stroke position and is in center and in a vertical position. As the second connecting member <NUM> continues to rotate clockwise, the member <NUM> moves past the center position, i.e. over-center, see <FIG>. In the over-center position, which corresponds to the second position of the linkage <NUM>, the linkage <NUM> mechanically locks the gate arm <NUM> in the horizontal position HP, because a force that pushes the gate arm <NUM> trying to lift the gate arm <NUM> cannot operate or "back-drive" the mechanism. Instead, the segment gear <NUM> will hit the second structural element <NUM> which serves as a fixed stop. In order to lift and "unlock" the gate arm <NUM>, the gear <NUM> must be rotated in the correct direction to remove the physical barrier. The correct direction is counterclockwise (the opposite direction of the arrow R).

The mechanism <NUM> with the linkage <NUM> and gear <NUM> is operated and powered by a gear train <NUM> and an electric motor <NUM>. The gear train <NUM> can comprise one or more stages (gears) operably coupled to the electric motor <NUM>. It should be noted that the gear train <NUM> and electric motor <NUM> are only shown schematically.

The described mechanism <NUM> is unique in that by rotating the gear <NUM> over-center to turn the gate arm <NUM> to the horizontal position HP with the gear <NUM> resting against element <NUM>, any attempted lifting of the gate arm <NUM> results in the gear <NUM> driving into structural element <NUM> and therefore mechanically locking the gate arm <NUM> in the downward horizontal position HP. For the purposes of the figures, specifically <FIG>, the 'droop' of the gate arm <NUM> below horizontal is exaggerated to demonstrate the principle when in practice it would be unnoticeable. The first structural element <NUM> equipped with spring buffer (spring <NUM>) acts as the resting location for an unpowered descent of the gate arm <NUM> and also provides a force to ensure the gate arm <NUM> does not return to the 'droop' state once torque is removed from the gear <NUM>. In a powered descent, the gate arm <NUM> effectively comes to a balanced rest between first structural element <NUM> and second structural element <NUM>.

The mechanism <NUM> provides passive latching of the gate arm(s). If the gate arm(s) is/are lowered without power, the gate will sit against the spring <NUM> of the first structural element <NUM>, intentionally not latching the crossing gate arm <NUM> so that emergency services may raise the gate arm <NUM> if needed. If the crossing needs to remain closed for a long period of time, authorized personnel may manually advance the mechanism to latch so that a pedestrian would not be able to lift the arm(s). Additionally, if the gate were to lose power once lowered and latched, it does not release the latching mechanism and will remain held in the down position (horizontal position) until powered up or manually raised. The mechanism <NUM> may be overridden by authorized personnel by manually advancing the internal gearing, but this is secured from the public.

Claim 1:
A crossing gate mechanism (<NUM>) comprising:
a linkage (<NUM>) operably coupled to a crossing gate arm (<NUM>), the linkage (<NUM>) comprising an over-center linkage,
wherein the crossing gate arm (<NUM>) is movable between a vertical position (VP) and a horizontal position (HP) via the linkage (<NUM>),
wherein the linkage (<NUM>) is in a first position when the crossing gate arm (<NUM>) is in the vertical position (VP) and in a second position when the crossing gate arm (<NUM>) is in the horizontal position (HP), and
wherein the over-center linkage (<NUM>) in the second position mechanically locks the crossing gate arm (<NUM>) in the horizontal position (HP).