Fuel efficiency

Good point about the glider kit, wish Kenworth would get their heads out of their -ss-s. Would love to have lift axle on trailer also.

 

WHY DOES EVERYONE WANT A 18SPD. ITS COMPLETE OVERKILL OTR. YOU'RE BETTER OFF WITH A 10 SPEED. YOU GUYS SEEM TO BE OVER COMPLICATING THIS. ON A 10SPD, 9TH IS USUALLY A 1 TO 1 RATIO WITH 10TH BEING YOUR OVERDRIVE. ON A 18SPD, 7TH HIGH IS A 1 TO 1 AND BOTH 8TH LOW AND HIGH ARE OVERDRIVES. I THINK A GOOD RATIO FOR YOU WOULD BE IN THE LOW 3s. TALL TIRES, NOT LPs. MICHELIN ALL POSITIONS SEEM TO WORK WELL.

WHAT MOTOR DO YOU WANT TO RUN? WHAT MPGs ARE YOU SHOOTING FOR?

 

BRO Is your caps LOCK STUCK???? IF so START pounding ON THE KEYBOARD AND YELLING!!!!

 

It all depends of the application. I pull heavy and run a lot of hilly two lanes. Having the ability to split the gears in this application allows me to keep the engine right where it operates best. A 10 is fine for many OTR applications, but I don't like the RPM spread for my application. Many fleets like MVT and Wally World do fine with 10's and tall ratios like 2.64. The nice thing about an 18 is that flexibility it provides. It is not overkill. I may not use ALL the gears ALL the time, but every one of them will get used at some point depending on what I am doing at the time. For me, it is better to have the flexibility than to not have it when I could use it. And it handles higher torque levels better. I have saved enough in weight on other specs on the truck that the added weight of an 18 over a 10 is inconsequential. There are many instances where all the gears are not used with a 13, 15, or 18, but drivers that have used them have used each one of those gears at one time or another to fit what they were doing at that time. You mention the 10 with 9 being direct. What about the 10 direct which would be a better application with a tall rear end?

I would guess a good counter question to yours, ducatijay, is "why are there so many against using an 18 and think it is overkill?" Each person needs to look at what they do, where they do it, and what would work best for their application. I have nothing against a 10. In fact I even like a 9 in some applications. But that is why we have so many transmissions choices.... there is no one size fits all solution to every application, even though fleets and the OEM's would like to make us believe it. And the plain truth is that many fleets spec 9's or 10's simply because their drivers would have 13, 15, and 18 spd trannies laying in parts all over the road because many do not know how to use them without blowing them up.

 

I am plated for 117k lbs, and run midwest to west and north west. You can keep that 10 speed in my case.
All depends on the weight and lanes traveled in my experience.

Martin

 

our company is running all DD13 and DD15 engines with 10 spd OD and 10 spd direct with 3.55 rear end Cascadia's.

Fleet average is 6.3 mpg and the newer (2010) trucks are over 7 mpg.

The cruise is set to 65 mph and the foot to 67 mph on some trucks.

I am driving a 2009 and averaged about 5.8 on history and last week was able to get it up to 6.6 MPG by adding in Lucas upper cylinder lube to the fuel.

We run close to gross all the time at 78,000+ and run in the upper midwest region primarily, ILL, WI, MO, MN, IA and SD.

 

According to the bossman, the fuel charts are claiming to get better mileage on the DD13.