Patent ID: 7931317
Filing Date: 2011-04-26
Classification: E01F

Abstract:
1. A trailer mounted crash attenuator, said attenuator comprising a front vertical frame attached to a tongue, a strike plate attached to a rear vertical frame, an intermediate vertical frame mounted on an axle, said axle mounted on wheels, each of said front, intermediate and rear vertical frames having top and bottom rails with opposing tracks and a longitudinal guide, a scissor assembly having an upper and a lower horizontal scissor frame mounted on the front, intermediate and rear vertical frames, each of said scissor frames having two groups of parallel scissor arms, each scissor arm of each group with the exception of a scissor arm closest the front and rear vertical frames is pivoted to three scissor arms of the respective other group at the middle and at its two ends, said pivoted ends of the scissor arms of the upper and lower scissor frames interconnected with vertical uprights, said scissor arms of each of said frames connected at the middle to a scissor arm of the respective other group with a pin having an enlarged head, said vertical uprights at the front, rear and intermediate frames mounted on rollers which are reciprocated in the tracks on the front, intermediate and rear vertical frames to permit the upper and lower horizontal scissor frames to fold on impact each of said longitudinal guides on the front, intermediate and rear vertical frames having a longitudinal slot for receipt of one or more of the enlarged heads of the pins at the middle of the scissor arms on one of the scissor frames to keep the scissor arms from twisting as the upper and lower horizontal scissor frames fold on impact, and, at least one self-adjusting shock absorber with staged metering such that it becomes stiffer as it is compressed, said shock absorber mounted in the scissor assembly.