L46A1 Mast SectionThe cause of the slide Hook, a simple circuit to prevent the empty slide hook of the tower crane
The empty slide hook of the tower crane is very dangerous Especially in the process of falling from high speed to low speed, once a slip Hook, light through the floor floor damage equipment, serious injuries and construction personnel. Why would there be a slide hook? In order to solve this problem, the crane manufacturer, http://www.fx68.net , has designed a simple circuit to prevent the overhead crane from slipping into neutral. The reason is that there is a long time gap in gear shift (such as too long gear gap, damaged contactor coil, aging delay head and so on) . In the control circuit of multi-speed Motor, in order to prevent short circuit between phases in the shift process, it is necessary to design 0.1 second neutral, otherwise it will cause the breaker trip or the contactor burn. In the control circuit of the brake motor of the lifting mechanism, the normally open contacts of each gear are connected in series. Once the contactor of a gear is not absorbed, the lifting mechanism will brake and stop working.
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There is a doubt: This circuit in each shift, the brake motor will be short of electricity and braking once, that will not damage the brake motor and the lifting mechanism? In our opinion, as long as the neutral time is within the appropriate range, it will not cause damage to the brake motor and the lifting mechanism. Because the brake mechanism has a braking distance, the brake motor will not brake until the power is cut off for about 0.5 seconds. If the neutral time is controlled under 0.2 seconds, the brake motor will move but not brake It is only when the gap is more than 0.5 seconds that the brakes really kick in, and there is a sense of concern. What does a half-second or more mean, anyway? That means a major security breach! Even if the brake at this time will cause damage to the lifting mechanism, that is the only choice to lose the pawn to protect the car.
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