Downshifting without revving up the engine?

It is a 2013 Freightliner with a new transmission. I don't know what brand the transmission is.

He has 30 years of driving experience. I asked him why he downshifts at 1100 without revving up the engine. I asked him did you read instructions to do that in the manual for the transmission or the manual for the truck. He said that he downshifts at 1100 without revving up the engine because that is how he has always downshifted through his 30 year career. So if it only works because it is a synchronized transmission, he must have been driving trucking with synchronized transmissions all his life.

 

Yes, he is able to get it in the next gear without touching the throttle. I don't remember whether or not the engine would jump several hundred RPM's.

 

As god prefers diesels said.
And being able to float shift helps.

 

Both ways is called being a good operator. The old timers that I grew up with did it both those ways. It depended on the many different situations you encounter while “pushing a diesel”. Back in the days of no mufflers Ed’s way would be done during times when you were trying to keep your smoke and noise down. I.e Late at night passed residence’s or places where you don’t want to be a loud sob.
Ed is most likely just using more brake to slow truck down with that style.

 

Still can’t wrap my head around the fact that if you are in 10th at 45mp rpm’s at approximately 1100 you downshift to 9, you need rpm at approximately 1500.

unless double clutching and you drop it in 9th and the rpm rises naturally?


That’s the part I don’t understand is the rpm either will rise naturally or you need to raise it to prevent a hard strain on the drive train no?

 

you are a seasoned driver and you of all people should know that physics wont allow for a downshift out on the real world road without revving to match the speed. its not humanely possible. unless of course its a company truck, you can grind a ram it into gear and break something forcing it in. So claiming you sat with some old timer in his passenger seat go from 1400 rpm at 40 mph to next lower gear when truck idled down to 700 rpm when it should have been 1800 is complete nonsense. Double clutching is only a timing thing. IT does not synch the gears like it does in a honda accord. Posting a video of the old cogger at doodson upshifting at idle around the yard is the same thing all cdl school kids can do. Old man doodson isnt gonna come off a highway at 40-50 mph downshifting without reving
Its very simple. for most trucks there is a 400 rpm drop between gears. so you need 400 rpm rise. split shifting with 18 you have a 200

 

I agree, and I understand the physics of shifting... but I have seen it done. It dosent make sense in my own mind either. I can idle shift up and down around a yard without touching the throttle myself but i understand that at that low rpm there is very little difference between gears.

The old guy that I saw do it always seemed the that the shifts were done at a much lower rpm than than one would normally downshift... Like maybe shifting at around 1000 rpm, in an old corn binder that I would downshift at like 1600. And it was never a very quick shift either... Maybe the transmission had alot of wear or slop... IDK. I've never been able to replicate it at anything above an idle.

 

I know what you mean and It’s hard to explain. I do it all the time without thinking about it. Its able to be done. The best way to explain how it can be done is how a truck can be left in top gear and brought down to a slow crawl just by lifting off the throttle and letting it slow down naturally. It will darn near idle down and just at the time when it starts to fight against the high gear its in (buck and shake) then you can select the gear it needs for the current speed and it falls right in without touching a peddle.

 

Ed doesn't have a synchronized transmission.
Even if Ed is double clutching you still have to match rpm to road speed to gears.
Ed is most likely pulling it out of gear and then braking to slow road speed to match next lower gear. Ed isn't driving efficiently. Ed isn't using engine braking. Don't be like Ed.

What Ed is doing is pointless. Yeah you can pull it out of fear and coast and brake and then let it slip into the next gear but if you are slowing to stop you will have to pull it right back out of that gear and down to the next.

I skip gears while down shifting all the time, but to do so you have to increase your engine speed a lot. But you get better engine braking that way, with or without the Jake brake.

 

Who ya calling an old timer, sonny.