(57) Horizontal platform lifting device, including a parallel arranged driving shaft (1)
superimposed on a lower horizontal support base (3), on both sides of which two similar
side lifting units are arranged parallel and opposite each other, which are simultaneously
driven by some driving means. Each one of the mentioned side lifting units includes
two pairs of superimposed St Andrew's crosswise linked levers (4), of which the lower
one has one of its lower ends (6) linked to a fixed point in the lower support base
and the other lower end arranged slidingly over the actual base. The upper ends of
the lower St Andrew's cross are linked to the lower ends of the upper cross and one
of the upper ends of the upper cross is linked to a fixed point of the lower side
of the lifting horizontal platform, while the other upper end of the upper cross is
arranged slidingly over the mentioned lower side of the mentioned lifting platform.
The mentioned driving means include a pulling cord coiling drum, a first cord returning
shaft (12), a second returning shaft (13), and a free transversal bar (14) fitted
at its ends with two wheels (15) which are supported on the internal edges of the
respective angles formed by the pairs of linked levers (4) at the connection points
(8) of the bar which forms the second returning shaft.
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