Is coasting in neutral bad

Illegal.

 

Why would an auto kick into neutral... what happens when you hit the brakes.. gotta be rough on driveline...

 

the auto freightliners i drove did that, too. and wouldn't hold cruise control on the desired speed, it would frequently slow down unless placed in manual mode.

 

Owning a 2014 crapscadia is bad. Coasting in neutral not a problem!!

 

You are required to have power on your drive wheels.

In some States as of this writing it is illegal to coast, as in moving down the highway or road in neutral.

More particularly with big trucks you must have the tractor in gear as you cross railroad tracks. You cannot shift while on the tracks. It is your responisbility to make sure you can finish a railroad crossing in one move without interfering with traffic or trains.

I have a feeling that this subject will draw strong opinions. If I had a choice between coasting and driving down the hill in nuetral, I rather do it in gear. Coasting introduces more problems than it's worth. For example if you are on a twisting downgrade in a rain and have the tractor in gear as you roll downhill you might actually be giving that trailer something to "Lean on" with it's weight. If you took it out of gear, that trailer might "Slip out" and put you into a tractor jackknife because there is nothing to hold it back once you exceed the traction available as you coast.

If you had a 6 mile downgrade and you were able to get to the bottom with the engine off burning zero fuel. Congrats. But you still have more uphills all around on the Earth. There is no way to continue to burn zero fuel. Unless you find a battery big enough to run a big truck from A to B without burning fuel.

A long time ago I was with DM Bowman of Frederick Maryland, and later with Williamsport. But I focus on Frederick because we had what was called a Trip Master computer that recorded idle time, shifting, speeds most particularly and other things. Each evening we downloaded the contents of the computer into the Ternimal. If you kept idle time to a certain percentage of overall engine hours each week, you got paid a extra 60 dollars or so. So you turned off the engine at every traffic light, and turned it back on when the light turned green. It was the easiest way to get your 60 dollars per week. Even though you replaced several starter motors each year. (Silly aint it? All this work to save a few dollars is wasted anyway when starter motors go out fleet wide....)

Using the tripmaster data. Coasting did not save a #### thing in fuel. Shutting off the engine did. In fact, besides the speed rules, you were counseled and then fired if you were a coaster in nuetral with their trucks. When you consider that every load without a Plant Supplied Pump you had your engine at 2300 RPM driving a exhaust turbo blowing off the tanker load of cement for a hour and 15 minutes or so several times a day. Throwing down a ocean of fuel as it were.

Ever since that foolishness with Bowman, I made sure to join only companies that has one rule, A speed Governor whatever it might be 72? 68? etc. Only one company FFE back in the late 90's took pains to mislead drivers with a false 65 mph speedometer Readout when it's actually a secretly governed 63 mph truck. That showed up when I bought GPS and started to wonder why the mile averages were not showing 65 like it was supposed to. An investigation with GPS and my Laptop revealed that FFE had our truck at 63 and the speedometer was defective. THAT raised a big ruckus once I showed the evidence to the shop and then to safety. Apparently insurance rates for a 63 mph truck was a great deal of money savings fleetwide compared to say 65 mph trucks that they advertised back then. Enough to keep stuff like that a secret then. Im over it. And they are too.

Finally but not last... I offer you this parting shot.

When I started back in the 80's 4 or 5 miles to gallons was great. When I stopped in the 2000's 6 miles to the gallons was considered great.

Isnt that terrible. Fuel mileage sucked then it still sucks today. Why arent we getting 50 miles to gallon and robots driving everywhere? Money. That's why.

 

As long as the engine is actually running, the transmission oil pump will function, so it will not bother the tranny to coast down a hill in neutral.
I think a modern engine will use next to zero fuel when going down a hill as it is programmed to give a certain amount of fuel for a given rpm, if the engine is going faster due to gravity, it would give zero fuel. Therefore I think you may actually use more fuel by having it in neutral as it has to give itself fuel to keep running, vs zero fuel in gear going down hill.
But I'm no engineer.