Crash attenuator apparatus
Apparatus for absorbing energy when impacted by a vehicle includes a backstop structure, a track extending to the backstop structure, a plurality of collapsible tubes supported by spaced independently movable supports on the track, and stabilizer structure stabilizing the supports in three planes during movement of the supports on the track and collapse of the tubes.
1. Apparatus for absorbing energy when impacted by a vehicle, said apparatus comprising, in combination:
a backstop structure affixed to the ground and extending upwardly therefrom;
an elongated track extending along the ground toward said backstop structure, said track including two parallel rails spaced from one another, each of said rails having channel defining structure defining an elongated channel, said elongated channels spaced from one another;
a plurality of supports including tube support structure mounted for independent movement along said track and extending upwardly from said track, said supports being spaced from one another along said track and spaced from said backstop structure, said supports disposed at right angles relative to the direction of movement of said supports along said track;
a plurality of elongated, collapsible, hollow metal tubes supported by said tube support structure in fixed position relative to said supports and extending between adjacent supports with opposed ends of said tubes abutting said adjacent supports, said tubes having longitudinal axes extending parallel to one another, parallel to said track and disposed at right angles to said supports; and
stabilizer structure including the channel defining structure of said rails operatively associated with said supports stabilizing said supports to prevent tilting of said supports backward or forward, sideways or about a vertical pivot axis whereby said tubes are maintained at right angles to said supports when said supports move along the track toward said backstop due to impact between the apparatus and a vehicle, and whereby each of the collapsing tubes between adjacent supports will collapse substantially uniformly about the longitudinal axis thereof when compressed between said adjacent supports, said channel defining structure including spaced upper and lower elongated guides and said supports including rigid frameworks, said stabilizer structure further including wheels attached to said frameworks and supporting said frameworks positioned in said longitudinal channels between said upper and lower elongated guides.
2. The apparatus according to claim 1 wherein said supports include wheel mounts attached to said frameworks and wherein said wheels are rotatably mounted on said wheel mounts and positioned on and supported by said lower elongated guides, at least two wheels on each wheel mount, with one wheel disposed behind the other wheel.
3. The apparatus according to claim 1 wherein said stabilizer structure additionally includes low friction plates attached to said frameworks and engageable with upper rail surfaces of said rails adjacent to said channels.
4. The apparatus according to claim 1 wherein said tubes have four sides and have a square cross-sectional configuration.
5. The apparatus according to claim 4 wherein said tubes are supported with two sides thereof disposed vertically and two sides thereof disposed horizontally.
6. The apparatus according to claim 4 wherein said tubes are supported with all four sides thereof disposed at substantially 45 degrees relative to horizontal and vertical.
7. The apparatus according to claim 1 additionally comprising a nose assembly spaced from the support most remote from said backstop structure and responsive to vehicle impact on said nose assembly to move toward the backstop structure.
8. The apparatus according to claim 1 wherein said track is attached to said backstop structure.
9. The apparatus according to claim 1 additionally including overlapping side panels connected to said supports and telescoping responsive to movement of said supports along the track toward said backstop structure.
10. The apparatus according to claim 1 additionally including shock absorber structure at said backstop structure.
11. The apparatus according to claim 7 wherein said support most remote from said backstop structure includes tube support structure supporting tubes with distal tube ends thereof spaced from said nose assembly before vehicle impact on said nose assembly.
12. The apparatus according to claim 1 wherein said rails are I beams.
13. The apparatus according to claim 1 wherein the elongated channels of said rails face inwardly toward one another.