1. An access device for providing access between a lower level and an upper level, the access device including a main body
which includes an upper section and a lower section which is pivotally connected to the upper section, the upper section being
mounted for pivotal movement about an upper section fixed pivot mounting between an access position and a stowed position,
the device further including a drive mechanism operable to cause movement of the upper section between the access and stowed
positions, the upper and lower body sections being pivotally movable relative to one another between an extended position
in which they are disposed generally end to end and a retracted position in which they are disposed generally side by side
in a folded configuration such that the upper and lower body sections are positioned substantially vertically or at a rearwardly
inclined angle in a position which is upward and rearward of the upper level, the device further including a control link
assembly for controlling the movement of the upper and lower sections between the extended and retracted positions, the control
link assembly being movable in response to movement of the upper section between the access and stowed positions and including
a motion generating link operatively mounted for pivotal movement in response to movement of the upper section between the
access and stowed positions, the motion generating link being operatively connected to the drive mechanism, the control link
assembly further including a first transfer link assembly operatively connected to the motion generating link and being movable
by the motion generating link in response to movement of the upper section between the access and stowed positions, the first
transfer link assembly including a first link member having one end portion pivotally connected to the upper section of the
main body, and a second link member operatively connected to the first link member in spaced relation to the aforementioned
one end thereof, and wherein the control link assembly further includes a coupling link pivotally mounted to the upper section
of the main body and operatively connected to the first transfer link assembly and a second transfer link assembly operatively
connected to the coupling link and the lower section of the main body, and wherein the first and second link members, the
coupling link and a portion of the upper section of the main body form a four bar linkage, the first link member being operatively
connected to the motion generating link, and wherein the coupling link includes two arms which extend away from one another
from a junction region, one of the arms being connected to the second link member, the two arms forming a generally V-shaped
configuration, with a cross arm extending between the two arms in spaced relationship from the junction region, and wherein
the second transfer link assembly includes a third link member and a fourth link member, the third link member being connected
between the coupling link and the fourth link member which in turn is operatively connected to the lower section of the main
body, and wherein the device further includes adjustable link means which is operatively connected between the coupling link
and the lower section of the main body so as to urge it towards either the fully extended or retracted positions, the adjustable
link means including an elongated element, one end of which is operatively connected to the lower section of the main body
and the other end is operatively connected to the other arm of the coupling link.
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