This design dates back to the late 1950’s, and has several useful features incorporated into its design. The motor has a flywheel, which then has a small pinion gear. A very large drive gear meshes with the pinion; this large drive gear occupies the entire wide of the locomotive’s cab. The drive gear is fitted to a shaft which goes to the front of the locomotive. There, a coiled steel belt provides power to the from truck of the locomotive.
It is an interesting design, but the large gear limits this mechanism to powering only locomotives with wide cabs or bodies. In operation, the steel spring drive produces an odd surging in the locomotive, with the locomotive speeding up and slowing down, not as realistic as today.
So, too, the brass locomotives of the 1960’s were beautiful, but many of them simply would not run at all. And if they did run, they required a good deal of effort by the locomotive’s owner to wreak out adequate performance.
So, in that context, the Lionel locomotives of the 1960’s were not as bad as they seem today. And, in many ways, they helped the model railroad hobby to improve. While Athearn’s Hustler locomotive remained belt driven until the end, the comparable Lionel Husky had a gear drive. And a headlight, something that the Hustler never had.