Lanyards are still important and common components of personal systems protecting against falls from a height. Experience with dynamic strength tests of lanyards indicates that test methods based on ...EN and ISO standards do not make objective assessment possible. This paper presents the results of theoretical and laboratory investigations of the performance of adjustable lanyards during fall arrest. The obtained results indicate that methods of testing and assessment based on those standards demonstrate considerable shortcomings when applied to low elongation lanyards. The assumptions for improved requirements and test methods of lanyards made of e.g., steel wire and aramid ropes are also presented.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Based on the requirement of dynamic strength in free-wheeling toys at the toy safety standard, we designed and developed the practical automatic dynamic strength tester. The tester, taking Siemens ...S7-224 PLC to control the motion of Minas A4 Series AC Servo Actuator, uses Pulse Train Output generator issued variable frequency high-speed pulse to control Servo Actuator, applies internal high-speed Counter to receive and count the feedback signal coding of Servo Actuator and applies Pulse Width Modulation generator to realize speed synchronization following function. Using this tester can not only be realized as the automatic test of dynamic strength in free-wheeling toys and greatly improved the precision of the test but also can enhance the level of whole system’s automation.
Geometrical parameters of the “wheelset—rail track” system are mutually related. Currently, a very topical issue is the question of a possible adjustment of the regulatory framework in the ...“wheelset—rail track” system in order to take into account the actual state of the track, turnouts and wheel park on the railway network.Any changes made in order to reduce the maintenance of wheelsets or tracks are possible only when the safety of train traffic is unconditionally ensured.The most difficult problem in determining the possibility of changing the standard for the minimum thickness of the flange of car wheels is the problem of passing the turnouts. In the event of an incorrect setting of the standard for the minimum thickness of the flange of the wheels, the passage of carriage along the turnout can be accompanied by unfavorable and even dangerous phenomena. The most dangerous of these are wheel strikes against retracted point rail, ramps on the crosspiece at large angles, and strikes against counter rails. These phenomena cause both disruptions in the geometry of the rail track of the turnout switches and crosses, and fractures of the elements of the turnouts. They should be excluded.Calculations and modeling based on the results of the study of statistical distributions of dimensions obtained by mass measurements on the railway network are the basis for the assignment of norms and tolerances in the “wheelset—rail track” system. The results obtained in the calculations should be verified by dynamic-strength tests directly on the track.The article discusses the results of dynamic and strength tests to determine the effect of cars with different geometric parameters of wheelsets on turnouts with pre-formed average network and maximum permissible dimensions of the rail track parameters on the turnout and in the cross node. The minimum thickness of the wheel flange in the tests was 21.5 mm. The carriages of the test train during the test trips were loaded to the maximum permissible size and in an empty state. The tests were carried out at the Test Center of the JSC “VNIIZhT”.
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