I have been driving now for about 5 years and this idea has be percolating in the back of my mind for a good while.
I would like your thought's on it.. here go's nothing..
I haul a regular 53 ft dry freight trailer. I don't get in the dirt much and am usually on highway's 99% of the time.
ok the speed limit's on the highway's varies any ware from 55 to 85 and depending on how my truck was setup the gearing would be ok at some speed's and not others. this has always bugged me.
What if I used a really high gear rear end something like 2.75 ratio, with a 13 speed tranny and an aux 4 or 5 speed tranny on the end of the 13.
the 5speed aux tranny I would use to adjust the final gear ratio.
so I slow states like ca, ohio and illanoies I would put it in the lower gears to make the truck sit in my sweet spot at 55 mph. When I get to a faster state I put the aux tranny in to a higher gear so I can maintain the engine rpm in the sweet spot at say 65mph and so on all the way up to 85mph.
I would want the aux tranny to have gears that only change say 100-200 rpm per gear.
I don't know much aux tranny's other then I have seen them used on dump trucks.
this idea is not about getting the best fuel mileage but it's about letting my truck go the legal speed limit anywhere I happen to be with out over or under revving my engine.
thank you for your time and consideration, your thought and opinion's will be muchly appreciated