The All Terrain Heavy Hauler (AT-HH) was a model of walker used by the First Order during its conflict with the Resistance. Two were used during the Battle of Crait to tug a superlaser siege cannon towards the Resistance base. Although their primary purpose was to tug massive ground weapons, they were far from defenseless. The actual cables used to tug the superlaser were composed of 27,572 steelton wires, and aside from their impressive defenses of a medium fire-linked dual laser cannon on each corner of the mech as well as matrixed composite armor comparable to the All Terrain MegaCaliber Six. They were also backed up by a complement of patrolling snowtroopers, AT-M6s, First Order AT-ATs, and TIE starfighters.
AT-HHs were designed to complete the unique job of pulling massive loads across the battlefield. Their unusual multi-legged design, comparable to crustaceans and insects, provided immense power while giving the insurance of still being able to move if one or more legs were damaged.
The walker had three rows of rotatable and reposition-able legs; with the front consisting of eleven, while the middle and rear rows had ten each. Redundant legs were included to serve as a back up once the primary legs had failed. Each leg was suspended from a sturdy dowel structure and made with heavy-duty hinge joints and refined durasteel bearings. They were powered by a main piston actuator, combined with heavy "knuckle" actuators and hydraulic "tendon" pistons. This design proved highly successful, with the tug walkers being able to complete their objectives with more than forty percent of their limbs inoperative during field tests on Dromondar Beta.
The flat top deck of an AT-HH was covered in thick armor plates and each corner had its own medium fire-linked dual laser cannon, four in total. The turrets were controlled from the two engineering and gunnery stations located on both the starboard and port areas of the walker. The bridge was located on the front of the deck offset towards the starboard side by the primary sensor node hub. It was there that the First Order walker pilots and the commander were stationed in a configuration comparable to an AT-AT.
In battle, AT-HHs used a combination of escorts and its own defenses for protection. Each strand in its tow cables used to connect the walker to its load were composed of a bundle of 27,572 steelton wires, and were able to withstand direct laser cannon fire. They can be used to haul anything from disabled warships to prefabricated base modules and are powered by its on board fusion reactor.
In 34 ABY, the First Order deployed a superlaser siege cannon to crack open a the frontal fortification of the Resistance hideout on the planet Crait. During the ensuing Battle of Crait, the cannon was successfully tugged underneath the planetary shield by two AT-HHs.
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