Design for Retractable Staircase for Buses
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Concept 2: In concept 2, gas springs act as the load-bearing components and the
driving force of the motion of the retractable step. To ensure smooth folding of the
retractable step, an inversion of a single slider crank mechanism, i.e., Whitworths
Quick Return Mechanism, was employed to provide the same. In the mechanism, the
slider was connected to the door which provided the requisite input motion in the
form of rotation of a slotted link which enabled the folding motion of step.
Concept 3: In concept 3, sensors were used to detect the opening and closing of the
door. When the door opens, sensors provide signals to a linear actuator which drive
a parallelogram linkage to unfold the step.
This concept is the most efficient solution to our problem, but components used in
this concept are costlier in comparison with those used in other concepts. The delay
associated with detection of the opening and closing of the door increase the overall
unfolding time of the step.
Fig. 2 Side view of concept 2
Fig. 3 Model of concept 3