[sparkycuda]

Interesting that you were breaking the teeth on final gear. In a spur gear setup, that is the gear producing the most torque, all concentrated on a single tooth. Planetary gearsets typically have three or more gears meshing on the output, spreading torque over several teeth, so less strain on individual gears. On 1:1 bulldozers, some final drives distribute torque over 5 or 6 planet gears.

Always look for the binding conditions others have mentioned, but using planetary sets do have an advantage in large torque applications.

Ken