In these sort of cranes, hoist would seat on bottom flange of girder and moves along it.
Main Specifications Of Under-Slung Single Girder Overhead Cranes
Connection between girder and end carriage:
Considering special conditions of the place which the crane would be setup, there are variety of designations to connect end carriage to the girder to achieve maximum hook level.
Regarding to the top wins and losses it could be understood that under-slung single girder crane could be a good choice for capacities lower than 10 ton and for special buildings.