Underhung Cranes are used typically for lighter capacity applications, where end approach or application requires a building supported system. The wheel operates on either the lower flange of rolled sections (I-beam or wide flange) or patented track.
Engineered Lifting Systems can design and furnish underhung cranes and components for a host of applications.
Underhung cranes can be provided in single and double girder configurations based on span, capacity, mechanical clearances and service factors.
Here are a few samples:

This 5-ton underhung crane is used daily in a Class C application

5-ton underhung crane used in steel processing

20-ton underhung crane Class A service was designed to meet critical end approaches