GEOMETRICAL ANALYSIS OF THE HINGE MECHANISM OF A CENTRIFUGAL LIFT SPEED LIMITER WITH TWO OUTPUT LINKS

The article draws attention to the emergence of new promising designs of double-acting centrifugal speed limiters with a horizontal position of the axes of their devices controlling the excess speed, for example, the design of the speed limiter Vega, manufactured by Dynatech, with a horizontal position of the axis of its centrifugal device controlling the overspeed and the counter arrangement of its working bodies. The structural scheme of a similar speed limiter developed at JSC “Mogilevliftmash” is presented, which differs by collinear arrangement of the pulley and its centrifugal mechanism. The attention is paid to the absence in the free press of the design and calculation methodology of the above-mentioned speed limiters with the counter arrangement of the working bodies. The structural scheme is analyzed and attention is drawn to its asymmetry. The geometrical analysis of the articulated crank-and-rocker mechanism of the speed limiter with two output links (rocker arms) connected by connecting rods with a common input link (crank) is carried out. The dependences of the displacement of the output links on the angle of rotation of the input link are established for both parts of the mechanism, and their difference is confirmed. For the investigated speed limiter with specific dimensions of the mechanism links, the actual asynchrony of the displacement of the output links is determined. Attention is drawn to the necessity to ensure invariance of operation of the double-acting speed limiter regardless of the direction of rotation of its pulley. It is shown that non-synchronous movement of working bodies can lead to partial loss of functionality of the speed limiter and, accordingly, transformation of the double-sided limiter into a single-acting one. The problem of expediency of selection of possible variants of optimum combination of sizes of links of the mechanism is formulated for reduction of movement asynchrony of its output links and possibility of using the investigated structural scheme in precision mechanisms, in particular, in the double-acting centrifugal lift speed limiter.