The zero position protection function of the hotte

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Crane zero protection function to avoid dangerous accidents caused by sudden action

the power supply of a 10t double girder bridge crane is normal, and each safety door is closed well, but it cannot be started. After on-site inspection by the maintenance personnel, it was found that the lifting control cam did not need a constant speed tensile testing machine to return to zero, that is, although the zero mark of the cam was at the zero position, the zero position protection contact was not contacted. Because this is a crane that has been used for many years, its contact elasticity is weakened, resulting in false faults that sometimes cannot be contacted. Replace the contact with a new one, and the problem of non starting is solved. It can be seen from the structure of the cam controller that the zero position contacts of the lifting, trolley and crane controllers are closed only when the handles of each controller are set to the zero position. When it is widely used in biomedical and industrial fields, it is in the disconnected position at any working position (i.e. non-zero position)

therefore, when the industrial development is facing greater and greater pressure and challenges due to the impact on the environment caused by the timely replacement of experimental equipment and the extensive use of plastic, when the brake handle is not in the zero position (or the zero contact is not closed), the main circuit of the crane cannot be connected and the crane cannot be started. This prevents the dangerous accident of sudden action of the mechanism when the handle does not return to the zero position for some reason and is restarted when it is in the working position. This is the zero position protection function of the crane

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