Patent Application
20090091113
The present invention relates generally to an automatic barrier, and more particularly, relates to an automatic, extendable barrier that is mounted on a vehicle.
Buses often have a crossing arm that extends out from the front of the bus generally parallel to the longitudinal axis of the bus. The crossing arm is typically automatically deployed by the driver when the bus is temporarily stopped to pick up or let off passengers, particularly children. The crossing arm is intended to prevent passengers from walking immediately in front of the vehicle. When the crossing arm is deployed, passengers tend to walk around the barrier, a distance away from the front of the bus, where the driver can see them.
The conventional crossing arms are typically actuated by a motor to pivot the arm from a first position, generally parallel to a front bumper of the bus, to a second position, generally parallel to the longitudinal axis of the bus. However, the linkage between the motor and the arm has a relatively high failure rate due to the typical loadings associated with a cantilevered system, including loadings imposed by the arm itself, external loadings on the arm, and vibration, among other things.
Thus, there is a need for an improved barrier that is simple to operate and less vulnerable to failure.
The above-listed needs are met or exceeded by the present crossing arm for a vehicle including a plurality of hollow telescoping members. The telescoping members are mounted onto the vehicle and configured for extension with respect to a surface of the vehicle. The members define a variable volume chamber, where the chamber has a minimum volume when the members are nested, and the chamber has a maximum volume when the members are extended. An actuator is in fluid communication with the plurality of telescoping members and is configured for delivering fluid to the chamber to move at least one telescoping member with respect to a second telescoping member to extend the crossing arm.
A crossing arm having a telescoping axis that is parallel to a longitudinal axis of a vehicle includes a centermost telescoping member centered about the telescoping axis, and at least one generally hollow second telescoping member that is concentrically disposed about the telescoping axis. One of the second telescoping members is configured to permit the reciprocable telescoping motion of the centermost telescoping member with respect to the second telescoping member. A generally hollow outermost telescoping member is concentrically disposed about the second telescoping member. The centermost telescoping member, the second telescoping member and the outermost telescoping member are in sealed fluid communication with an actuator configured for delivering fluid. The centermost telescoping member is extensible and retractable when the actuator is actuated.
An alternate embodiment of crossing arm for a vehicle includes a plurality of hollow telescoping members. The telescoping members are mounted onto a side surface of the vehicle and configured for extension generally parallel to the longitudinal axis of the vehicle and from the side surface of the vehicle. The members are sealingly and slidingly attached to each other to define a variable volume chamber, where the chamber has a minimum volume when the members are nested, and the chamber has a maximum volume when the members are extended. An actuator is in fluid communication with the plurality of telescoping members and is configured for delivering fluid to the chamber to move at least one telescoping member with respect to a second telescoping member to extend the crossing arm. A fluid tank is mounted on the vehicle and in fluid communication with the actuator for delivering fluid to the actuator.
Referring to
The crossing arm 20 is employed for the purpose of preventing people from passing too closely to the front of the bus 10 so that they can be observed crossing the path of the bus by the driver. The crossing arm 20 is telescopically moveable from a retracted position (
In the preferred embodiment of crossing arm 20, the crossing arm includes a plurality of telescoping members 22 that are generally cylindrical and hollow. The telescoping members 22 concentrically nest with each other about a telescoping axis “T” that is generally parallel to the longitudinal axis “A”, while in the retracted position. In the extended position, each of the telescoping members 22, except for an outermost member 24, extends from a proximal end 26 of the crossing arm 20 along the telescoping axis “T” to be generally horizontal with respect to the ground.
A centermost telescoping member 28 has an enclosed distal end 30, a proximal end 32, and a body 34 extending between the ends. The distal end 30 is preferably rounded to eliminate sharp corners. A generally annular lip 36 is disposed on an exterior surface 38 of the body 34 at the proximal end 32.
Adjacent to and concentric with the centermost telescoping member 28 is the second telescoping member 40. The second telescoping member 40 is generally similar to the centermost telescoping member 28 in that it has a distal end 42, a proximal end 44, and a body 46 extending between the ends. However, the distal end 42 of the second telescoping member 40 has an opening 48 defined by a generally annular shoulder 50. The opening 48 permits the centermost telescoping member 28 to protrude out from the distal end 42, and to slide relative to the second telescoping member 40.
A generally annular lip 52 is disposed on an exterior surface 54 of the second telescoping member 40. The second telescoping member 40 is slidable within an adjacent telescoping member 22.
In
The outermost member 24 forms an outer housing 56 of the crossing arm 20. The outermost member 24 is generally cylindrical, having a distal end 58, a proximal end 60, and a body 62 extending between the ends. At the distal end 58, the outermost member 24 has a generally shoulder 64, similar to the shoulder 50 on the second telescoping member 40. The proximal end 60 is sealingly engaged with a hose 66.
The crossing arm 20 is actuated by an actuator 68, as known in the art and commercially available. The actuator 68 is supplied with fluid, typically air, from an air tank 70 mounted on the bus 10, however it is contemplated that the actuator can use any type of fluid (i.e. liquid or gas). The actuator 68 pushes the fluid through the hose 66, which is connected to a chamber 70 formed within the crossing arm 20.
The telescoping members 22 define the generally fluid-tight chamber 72 having a variable volume. When fluid is pushed into the crossing arm 20, the telescoping members 22 are preferably deployed in sequence with the centermost telescoping member 28 extending outward (in the direction of the arrow) first, then the second telescoping member 40, in sequence until all members are fully telescoped. With the telescoping members 22 extended, the chamber 72 has increased volume as compared to the retracted position.
The driver preferably initiates the actuator 68 with an input device 74 located in the cab of the bus 10. It is contemplated that the actuator 68 can be configured to actuate only when the bus 10 is stopped. The actuator 68 is preferably configured to regulate the force with which the telescoping members 22 are pneumatically deployed outward. Further, the length of extension of the crossing arm 20 can be determined for each individual bus 10, or can be based on regulations for bus operation.
The shoulders 50, 64 on the larger diameter telescoping members 22 allow each smaller telescoping member 22 to engage the shoulder with the smaller member's lip 36, 52, thereby preventing the smaller member from disengaging from the crossing arm 20. It is contemplated that other mechanical stops can be used instead of a lip/shoulder engagement.
When the telescoping members 22 are retracted, the actuator 68 will draw out the fluid from the chamber 72 and put it back in the tank 70. This creates a vacuum in the chamber 72, and each telescoping member 22 will withdraw into the nested position to create a smaller chamber volume.
The telescoping members 22 are preferably plastic, and more preferably high impact plastic. However, any rigid lightweight material can be used.
Preferably, the crossing arm 20 is near perfectly horizontal in the extended position when mounted on the side surface 14 of the vehicle 10 horizontally. In other words, the telescoping members 22 preferably do not sag when they are extended. It is preferable for the crossing arm 20 to be straight and rigid on windy days when the arm is likely to be buffeted about by cross winds.
It is contemplated that additional lips or other mechanical structures can be added along the length of the telescoping members 22 to keep the crossing arm 20 generally aligned with the telescoping axis “T”. For example, an additional shoulder/lip at the distal end of each telescoping member 22 (with the exception of the centermost member 28) will counteract the bending moments of the telescoping members 22 distal from it. The shoulder/lip at the distal end of the outer member 22 would interface with the shoulder/lip of the proximal inner tube, thus preventing the segments from shooting out of the crossing arm, and also reinforcing the chamber seal. Alternately, the lip can be thicker along the length of the telescoping member 22. Further, the amount of fluid deployed into the chamber could also act to keep the deployed arm generally straight.
Referring now to
The guard structure 76 includes a generally “wedge”-shaped body 78 that extends from the crossing arm 20 to the side surface 14 of the bus 10. The body 78 includes a front surface 80, a back surface 82 configured for attachment to the vehicle 10, a side surface 84 attached to the crossing arm 20, an upper surface 86 and a lower surface 88. The front surface 80, the upper surface 86 and the lower surface 88 are preferably smooth.
While particular embodiments of the present crossing arm have been shown and described, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.
