The vehicle does not move
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We have a crane with two motors: one is responsible for the up and down movement, and the other is responsible for movement along the guide rails. It was working normally before, but now it’s malfunctioning – it can only move upward; it cannot move downward or sideways. Individual testing showed that the coils of the 4 AC contactors were all in good condition; applying voltage directly to the coils allowed them to engage properly. Thinking it was a problem with the control handle, I tried shaking it off, but it still didn’t work. Finally, the wiring was modified; each coil needs to be powered separately in order to function properly. Does anyone know why the fault occurred before the route was changed?
You are referring to electric hoists, right? Such electric hoists have limits – they can rise but not descend, probably because the cut-off limit switch has not been reset. They don’t move side to side because both limit switches have been activated; these limit switches are connected in series with the contactor coil.