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Abstract: The mechanisms of the elevators in X usually have a simple structure with hinged, scissor-type bars, having one or more levels. In the last period, models of elevators with articulated bars in X with complex structure with triad type kinematic chains were made. For such an elevator with triadic chains, a construction diagram (dimensioned drawing) is presented, after which the kinematic diagram of the plane mechanism with articulated bars and guided rollers is executed. The structural-topological analysis aims at the mobility calculation and is complemented by a frictionless static calculation.
Keywords: Elevator mechanisms, kinematic analysis, complex triad, kinematic chains.
1. Introduction
Elevators with articulated bars in X are flat structures mounted in parallel with one or more levels, being operated with hydraulic or pneumatic cylinders. These lifts are used more and more in car services, for lifting vehicles for current repairs below at the bottom.
In most of them, elevators with articulated bars in X are used for work at height (fig. 1, 2), at the top of which there is a platform, on which workers work [1,2,3,4].
Being built for higher heights, these elevators are operated with relatively long hydraulic actuators [5,6,7].
For working at lower heights (fig. 3, 4) non-articulated X-lifts with two levels are used, where the work table is moved vertically with a mechanical screw actuator.
It is noted in these elevators that the X-shaped bars are not articulated with each other, the respective bars being opposite and unequal in a deltoid quadrilateral (fig. 3), respectively opposite equal bars and articulated by the horizontal actuator provided with a screw (fig. 4).
These height-adjustable tables are mounted on the elevator with non-X-articulated bars, but articulated at the base on a four-wheeled carriage (fig. 5).
There is also the solution of making an elevator mechanism with articulated bars (fig. 6) and a single level, having in its structure two dyadic chains denoted LD (2,3) and LD (4,5).
2. Structural analysis of the X-bar elevator with complex chains
The dimensioned construction diagram (fig. 7) of an articulated X scissor elevator mechanism [8] is followed, after which the appropriate kinematic diagram (fig. 8) with articulated bars is deduced.
The construction diagram (fig. 7) also shows the screw actuator, which is driven by a...