A Caterpillar Crane is a mobile crane that runs on caterpillar treads, several
different Caterpillar Cranes can be seen all around Sodor and they are mainly used in quarries and other work sites. Some scrapped cranes have also been seen several times.
The ERTL models for the caterpillar cranes incorrectly refers to them as a "he" as if there is only one of them and as if they're sentient.
It's likely that the Caterpillar Cranes may have been intended for Thomas & Friends' sister show, TUGS, as they are more detailed than most of the other vehicle props, and were possibly made shortly before TUGS' cancellation.