Quote:
Originally Posted by alexthedoobieman
It is possible. Diesel Electric locomotives have successfully used this technology for decades. The rational is that tremendous loads can be moved from a dead stop. The drive wheels are relatively small compared to vintage steam locomotives so no transmission is actually needed.
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I think you have this mixed up. I don't think the size of the drive wheels has anything to do with not needing a transmission. Whether you have big wheels that need a transmission for lower gears or small wheels that need a transmission for going faster, you'd still need one. The reason diesel locomotives don't need a transmission is just because it uses electric motors. The big advantages to not having a transmission are weight saving, fewer moving parts, and less maintenance on not only the transmission, but the diesel motor itself. A motor that needs to only operate at a certain RPM for sustained periods lasts much longer than one that constantly changes RPMs (think highway miles vs. in-town miles in a car and their effect on the longevity and wear on the motor). Other advantages include electric motors just being more efficient than a transmission, having each axle powered by its own electric motor (instead of having them all bolted together like steam engines), and each electric motored axle is independently controlled, meaning that if one slips power can be adjusted. Wheel slip is one of the biggest problems a locomotive can have.