Do electric hoists installed on special cranes need to meet dual limit requirements

The load capacity of special equipment cranes is generally over 3 tons, and they are used in large factories, bridge construction, construction sites, etc. Compared with small electric hoists, they not only have a larger load capacity, but also must participate in annual inspections and have strict requirements for hazard investigation, especially in terms of limit requirements.

Because the height limit is a safety device on the crane that restricts the movement stroke and working position, its function is to automatically cut off the power source when the lifting device rises to the set or limit position, so that the lifting device will no longer continue to rise, avoiding accidents such as component damage caused by collisions between the lifting device and the crossbeam, drum, and arm components. Its safety significance is significant.

For example, special equipment cranes are currently required to meet dual limit requirements. The equipment mentioned here includes newly manufactured bridge and gantry cranes, which should be equipped with two different forms of height limit devices, namely dual limit devices, such as heavy hammer, flame arrester, pressure plate height limit devices, etc. Any two types of height limit devices should also be installed in the equipment in use, and a set of height limit devices different from the original configuration form should be added.

For electric hoists installed on special equipment cranes, corresponding requirements should also be met. Some electric hoists have touch type micro limit switches and friction clutches to ensure that subsequent safety accidents caused by the failure of the upper limit of the lifting mechanism leading to toppling do not occur.