Boss wanted me to train a new driver

18 speed, 20 mph is 4HI, basically a 18 speed is like an 8 speed with the ability to split all gears with a hi/lo grey button. you could also use 5LO at 20 mph but you would be lugging it a little. you could get away with it on level ground.

we really need 18 speeds because the trucks are quite heavy (102K max gross) and we pull allot of hills. the other transmission we have in some of our trucks is a 13 speed, 13 speeds only allow you to "split" the upper ranged gears. i have a hill on my route that i split gears on both lower and upper range gears, so sometimes it is necessary

 

eaton 18 speed shift pattern - Yahoo Image Search Results

 

it has been quite a while since i shifted a 10 speed, would take a little getting used to after shifting an 18 speed, every transmission is a little different.