The model has been one of the most complex projects ever undertaken by Bachmann. The opportunity to create a ground-breaking model also presented a range of engineering and production challenges. It is fortunate that six of the prototypes survive in preservation, enabling the team to conduct extensive site visits, creating a wealth of dimensional and other data, photographs and notes. It was clear that there are a vast number of detail differences between the eight original prototypes when new, plus modifications made during the vehicles' working lives, making a huge research project.
The complex rigging and gearing of the machines has been faithfully reproduced to imitate prototype operation as accurately as possible in this scale. Operation of the crane's jib and hook is achieved by a key mechanism in the rear of the crane body. The boiler hatches are demountable using a magnetic tool included in the accessory pack, permitting access to two sockets that turn to raise and lower the crane jib and hook. The tiny 'Safe Lifting Angle' indicator on the cab side operates in tandem with the jib mechanism. The four outriggers are poseable, the chimney can be stowed or raised, the roof hatch is hinged and the cab platform is hinged for access.