Under bridge access apparatus with cross-linking member connecting tower with vehicular chassis

An under bridge access apparatus, comprising:

• (a) a tower including a ladder section, and a platform section connected to said ladder section and that moves relative thereto;
• (b) a vehicular chassis including a turntable mounted on said vehicular chassis for rotation about a vertical axis thereof relative to said vehicular chassis, and a tiltable frame mounted on said turntable that pivots relative to said vehicular chassis;
• (c) a cross-linking member including a pair of elongate arms pivotally joined intermediate respective lengths thereof and extending between and connecting together said tiltable frame and said tower, a first arm of said pair of arms including an end mounted at a fixed location on said tiltable frame and another end slidably mounted on said ladder section, a second arm of said pair of arms including an end slidably mounted on said tiltable frame and another end slidably mounted on said ladder section, each of said first and second arms extending between and being pivotally connected to respective said ends thereof, wherein the cross-linking member moves between a first position, in which the cross-linking member extends vertically relative to said chassis, and a second position, in which the cross-linking member extends orthogonally relative to said chassis;
• (d) a first cylinder connected to said tiltable frame and to said cross-linking member such that said tower moves between a retracted position and an extended position relative to said tiltable frame by extension and retraction of said first cylinder;
• (e) a second cylinder connected to said ladder section and said end of said first arm of said pair of arms slidably mounted to said tower such that said ladder section slides between upper and lower positions relative to said cross-linking member by extension and retraction of said second cylinder;
• and
• (f) a catwalk extending between said tower and said base, said catwalk including a first walkway mounted on and against movement relative to said tiltable frame, and a second walkway mounted to said end of said second arm of said pair of arms slidably mounted to said ladder section, such that said second walkway moves only linearly relative to said first walkway during extension and retraction of said cross-linking member whereby said catwalk remains generally horizontal during the extension and retraction of said cross-linking member when said cross-linking member is in said second position.