It's a Team's Life
What is M for?
Recently after a conversation with a colleague I came to the conclusion that some drivers aren't using their transmission correctly. First let me say it's the AMT or Automated Manual Transmission that I'm referring to, whether it's a Fuller UltraShift Plus, Volvo I-Shift or a Detroit DT-12.
A lot of people call it an automatic but in reality it is not. In my world an automatic is a fluid drive transmission like the one in your car or an Allison automatic that are put in trucks. These transmissions have a pump that pumps fluid through the inside of the transmission to make you go. In an AMT, it is a manual transmission with all the gears and some sort of clutch. It is, simply put, a manual transmission that had the shifter removed and a x,y servo installed. That servo is operated by a computer that talks to the engines computer to get everything right for each shift. That is greatly simplified but that's the idea.
So what does M stand for? On each shifter paddle there are markings to tell you what each movement of said paddle will do for you. On most there is "D" which we all know is Drive, this will make us go forward. There is also an "R", which is reverse making you go backwards. Different manufacturers have other things happen when you move the paddle up, down, forward and back. There is also a switch that indicates Auto or Manual; this is the operating switch I'm referring to.
The Auto and Manual switch puts the shifting responsibilities on to you, the driver. Now I'm not saying you should use this function all the time, but there are times that you should take control of the shifting. Here's my example of when you should be in manual mode, you doing the shifting. You just finished climbing the Grapevine just north of L.A. You made it to the top in eighth gear, your loaded and need to stay in a lower gear to get to the bottom safely. Here's the thing, if you leave the transmission in Auto, engine brake on high you will get to the bottom, but you may overheat your brakes. The reason is, in Auto mode when the engine reaches a certain RPM the transmission will up-shift continuously till it reaches top gear unless you apply the brakes to keep you slowed down. This could be a hair-raising experience.
My goal is to go down a mountain without touching the brakes, that way if there is a need for the brakes I have them to use. By putting the transmission in Manual, it essentially locked in the gear you chose. Choosing which gear is different for each transmission. For us it's seventh or eighth gear depending on the load. In Manual mode the transmission will stay in the chosen gear and utilizing the engine brake we get to the bottom without touching the brakes, unless something happens that we need to, safely.
Sometimes the engine brake is so powerful in the highest setting that it will slow the truck down to far and in these instances I adjust the engine brake without touching the throttle to speed the truck up while still maintaining control.
The transmission can be placed in Manual mode for other reasons also. In heavy traffic that is slowly rolling put it in manual in a low gear and the transmission will not be going thru gears up and down trying to find the right one. Just don't forget to put it back in Auto mode for the most efficient shifting.
When we are
driving for fuel efficiency we strive for the lowest RPM the engine is
comfortable with and the opposite is true when going down a hill, as we want
high RPM to get the engine brake to be as efficient as possible.
Bob & Linda Caffee
TeamCaffee

Saint Louis MO
Expediters since January 2005
Expediting isn't just trucking, it's a lifestyle; 

Expediting isn't just a lifestyle, it's an adventure;

Expediting isn't just an adventure, it's a job;

Expediting isn't just a job, it's a business.