Liner Boy is the third major mecha of Kyukyu Sentai GoGoFive and easily the most unusual member of the team's arsenal. Built by eldest Tatsumi brother Mondo (with help from Kyoko Hayase), he is the only GoGoFive machine equipped with his own A.I. unit: Liner Boy needs no pilot, has his own voice and personality, and is effectively treated as the "sixth" Tatsumi sibling. Launching from Bay Area 55, he first appears as Max Liner, a futuristic high-speed bullet train, can also take the Max Shuttle (space shuttle) form, and finally stands up into the Liner Boy robot.

His big moment comes when he links with Victory Robo: using the V-Mode Braces and the command "3-5-6, V! Max Formation!", the two combine into Max Victory Robo, the powered-up core robo of GoGoFive. Liner Boy can additionally dock onto the Grand Liner, making him a versatile support mecha that fights on his own, serves as armor, or acts as the docking module for the team's super combination.

In Power Rangers Lightspeed Rescue the mecha is renamed Max Solarzord; paired with the Lightspeed Megazord (Victory Robo) it forms the Lightspeed Solarzord. Even in the American adaptation he keeps that autonomous, "living" personality, which makes him a genuine standout among all the Zords.

As a DX toy he was released in 1999/2000 by Bandai Japan as "DX Liner Boy" and by Bandai America as the "Deluxe Max Solarzord." The classic converts from train/shuttle into robot and docks onto Victory Robo / Lightspeed Megazord to form the big super combination, carrying the die-cast content typical of the DX GoGoFive line for a satisfying heft. In 2020 Bandai also reissued the mecha as a Super Mini-Pla model kit (forms Max Liner / Max Special / Liner Boy, compatible with Victory Robo and Grand Liner) — a highly articulated collector's alternative to the vintage DX.