Question on automatics

[Gummiente]

Excuse my ignorance here, but while I've had lots of experience with automatic transmissions in cars and pickup trucks I've no idea about how they operate in heavy trucks. I've been told that within a year I will be assigned a new International Pro Star with an auto trans as Kriska completes the replacement of their fleet. Having had very limited seat time in trucks to begin with, I am curious to know how these operate. Is it as simple as "PRNDL" or do you have to push a button for every upshift and downshift? Are they the equivalent of 10 or 13 speed manual setups? Can you still use engine braking (as in backing off the throttle and using engine compression, not the Jake Brake) to slow down?

[FLHT Ron]

Gummi,


The plows I drive are automatics. You still use a clutch to put them in DRIVE REVERSE and NEUTRAL. Once in DRIVE the truck changes gears on its own. You can over ride the Auto and lock it in a gear for hills etc. They do have a manual button and you can change gears the same as a manual transmission.

The one draw back I have is the truck wants to switch gears when you don't want it to.

Hopes this helps!

Ron

[buzzy]

they are auto shifters with manual overides. You have to watch when you're stopped on a grade as they will roll back if you aren't on the brake and throttle at the same.

when you are parked they need to be left in neutral.

[Gummiente]

Hmmm... Ron, when I went to a career day in Oshawa a couple months ago, I sat in one of the new Kriska 2010 Pro Stars... I distinctly remember there was no clutch pedal at all, only brake and gas pedals. Buzzy, does the true automatic have a manual shift option for 10 speeds or is it just for D, L2 and L?

[buzzy]

depending on tranny, they can be manual overide up to 18.

[Gummiente]

Ok, that helps. Re your advice about starting on a hill, I'm guessing that has to do with 48,000lb and gravity overcoming the "creep" function of the automatic? By keeping one foot on the brake and one on the gas, that would lock the torque converter and prevent the rig from rolling backwards when releasing the brake...?

[buzzy]

10/4...mr. truck driver.

[liner]

Ok, that helps. Re your advice about starting on a hill, I'm guessing that has to do with 48,000lb and gravity overcoming the "creep" function of the automatic? By keeping one foot on the brake and one on the gas, that would lock the torque converter and prevent the rig from rolling backwards when releasing the brake...?

These automatics have no torque converter..only a clutch.It is just your basic tranny with a clutch (no peddle) and instead of the driver doing the shifting it's done by computer.By keeping one foot on the throttle on an incline all you are really doing is riding the clutch.Its best to just keep your foot on the brake pedal.

[Gummiente]

10/4...mr. truck driver.
You're being funny, right?

[buzzy]

These automatics have no torque converter..only a clutch.It is just your basic tranny with a clutch (no peddle) and instead of the driver doing the shifting it's done by computer.By keeping one foot on the throttle on an incline all you are really doing is riding the clutch.Its best to just keep your foot on the brake pedal.

There is a lag in the torque conversion. When you release the brake to use the throttle on an incline, they will roll backwards unless you're driving with both feet.

[buzzy]

You're being funny, right?

Always. :36_6_4[1]:

[bikerboy]

There is a lag in the torque conversion. When you release the brake to use the throttle on an incline, they will roll backwards unless you're driving with both feet.

Not all them! i was just reading in highway star or some magazine like that, that eaton just came out with a new thing on their auto's

when ever you come to a stop and hold the brake pedal, as soon as you take your foot off the brake, the abs automatically holds the brakes on for another 3 seconds or until you hit the gas, whichever comes first, so that prevents rollbacks, and the 3 second limits prevents drivers from using this function as a parking brake.

[bikerboy]

Their are at least 2 types of autos in big trucks, there is the allison automatic, which is just like a car automatic, except there is no park on the shifter, but it does have torque converter and acts just like a car auto.

you don't see these in highway trucks normally, but were common in garbage trucks and school buses and other light duty jobs.

Then there is the autoshift. a manual trans that is shifted by a computer, some had a clutch pedal, some did not, the computer runs the clutch, none of them have park on the shifter either, just use truck parking brakes.

I have only ever driven allison autos. And the companys i have worked for are all old school guys and who knows how long it will be before they ever buy an autoshift.
i prefer the 18 speed manual over any other trans. with an 8LL a close second.


hey ron, snowplowing with an auto?? does that work well? we only run 18 speeds and 500 hp ISX cummins in our plows. it is alot of things to do at once sometimes, trying to shift, turn, drop plow and wing and turn on sander all at once.

[buzzy]

we had 6 auto shifters. we now have 2 and by february 0. we will never, ever buy another one.

The tractors have done as many miles on hooks as they have been doing miles on their own.

The trannys can't hold up to 63,500 kgs gross wt we haul. And they aren't worth a rat's waste in the snow

[buzzy]

hey ron, snowplowing with an auto?? does that work well? we only run 18 speeds and 500 hp ISX cummins in our plows. it is alot of things to do at once sometimes, trying to shift, turn, drop plow and wing and turn on sander all at once.

Now, that's a safety concern!

[maan]

we had 6 auto shifters. we now have 2 and by february 0. we will never, ever buy another one.

The tractors have done as many miles on hooks as they have been doing miles on their own.

The trannys can't hold up to 63,500 kgs gross wt we haul. And they aren't worth a rat's waste in the snow

Sounds like a nightmare..

[Gummiente]

And they aren't worth a rat's waste in the snow
Just out of morbid curiosity, why is that?

[maan]

Probably another severe duty scenario where they overheat, fail & breakdown.

[hotshoe36]

I know of 3 different types of automatics: The Allison is like BB said, a hydraulic uniy that depends on fluid pressure, and is a different animal. I knew a guy who had one in a highway truck, years ago. He liked it, but admitted to higher fuel consumption. He could get off the line very quickly, but made less power (as compared to my Fuller) at higher speeds. This cost him drive tire life until he learned to feather the throttle at lower speeds.
The Meritor has no clutch pedal, and is a computer-operated mechanical (normal) tranny, and the other one is the same except that the driver clutches first gear, and the computer does the rest. All of 'em have manual overrides, but we see all of 'em shifting at inopportune times on the Coquihalla in winter.

[PavementPilot]

...but while I've had lots of experience with automatic transmissions in cars and pickup trucks I've no idea about how they operate in heavy trucks...

One thing, they are automated not automatic. An automatic has a hydraulic valve body inside it to actuate the drives. Automated is a air or electric drive servo on a manual gear box that physically moves the shift forks from gear to gear. While I have driving a 6 speed Alison automatic with tridem and Super-B's I have also driven the automated Eaton 13 and 18 and the Meritor ZF 12 speed with and without clutch. Both Eaton and Meritor ZF use air servos on their gear boxes.

[ralph]

One thing, they are automated not automatic. An automatic has a hydraulic valve body inside it to actuate the drives. Automated is a air or electric drive servo on a manual gear box that physically moves the shift forks from gear to gear. While I have driving a 6 speed Alison automatic with tridem and Super-B's I have also driven the automated Eaton 13 and 18 and the Meritor ZF 12 speed with and without clutch. Both Eaton and Meritor ZF use air servos on their gear boxes.

FINALLY...someone that gets it/uses the correct terminology!

What's with your new signature line Pavement Pilot....do tell, do tell.

[PavementPilot]

What's with your new signature line Pavement Pilot....do tell, do tell.

Hey Ralph, go to my 'I haz jawb' (http://www.truckstopcanada.ca/forum/showthread.php?t=3843&page=2) thread to read more. I dont want to sidetrack this thread.

[1320]

always wanted to repeat a statement from an driver older then dirt i met down south

"Auto shift what???....Automatics are for sissy's...trucking aint for Sissy's"


^ was meant as a joke...however...some agreement to his statement..I road tested a pete 387 with an auto during after interview..Hated every second...although offered the job i had to decline the postion

[ralph]

What a great way for fleets to keep new/inexperienced drivers captive. Throw them in an automated transmission equipped truck and they will forget their formal training in regards to manually shifting. Limits where they can go to ply their trade afterwards doesn't it?

[FLHT Ron]

hey ron, snowplowing with an auto?? does that work well? we only run 18 speeds and 500 hp ISX cummins in our plows. it is alot of things to do at once sometimes, trying to shift, turn, drop plow and wing and turn on sander all at once.


I think they work fine. Like you said, one less thing to worry about. Just gotta remember to lock it into 8 or 9 on a 10 speed to keep you at the right speed to spread. It is alot easier than trying to switch gears and run all of the other stuff! Besides, you can hold onto a Timmies and still run everything else!!:rofl2[1]:

[maan]

slushboxes.. steel vs oil..

[Pipeman]

Before very long, they will all be autoshift or automatics.

I remember running 5 X 4, 4 X 4, and 9 speed roadrangers. What the hell, only 1 stick ???? We survived, and the auto's will also survive.

[Nosyaj]

Not all them! i was just reading in highway star or some magazine like that, that eaton just came out with a new thing on their auto's

when ever you come to a stop and hold the brake pedal, as soon as you take your foot off the brake, the abs automatically holds the brakes on for another 3 seconds or until you hit the gas, whichever comes first, so that prevents rollbacks, and the 3 second limits prevents drivers from using this function as a parking brake.

Don't mean to be a smart donkey but I just couldn't resist! Big trucks run on diesel not gas. Thats why most drivers call it a throttle!:nenernener:

[bikerboy]

Don't mean to be a smart donkey but I just couldn't resist! Big trucks run on diesel not gas. Thats why most drivers call it a throttle!:nenernener:

yes i know, i think i was just typing fast and gas was quicker to type.
its a throttle!

[maan]

Gas is so common that most wouldn't know the diff.

Even with gas, it would be correct to say throttle.

Hit (or press) the (gas) pedal ..

Never heard hit or press the diesel..

Diesel also means engine type..typically or comes to mind.

You don't think engine typically with the word gas..

& no ..i'm not drunk bb,............................................... :rofl2[1]:

[Pipeman]

When I first came to Alberta in the mid 60's, I drove a Model LR Mack that had 3 transmissions in it.

Today, give me an Allison Automatic any time !!!

[MHL1965]

My last ride had an Autoshift with a Detroit 515hp (Century Class). The one before it had the same tranny with the Mercedes (A CMF Columbia) and 385hp. You would never know the two tranny's were identical.

I am sure the final drive may have been different but they were both 10 speeds and they just worked different. The lack of power in the Columbia had me HATING that tranny. The Detroit made me tolerate it. I drove a stick for 10 years, so it wasn't like I was some newbie, but I grew to really appreciate the auto in traffic. It wasn't as good on hills because it wouldn't downshift until I fell right off the torque curve, so I often shifted it in manual mode. Just a little paddle on the column and I would slap it up and down through the gears like an f1 driver.

Now, If I had a choice? I dunno. I really got used to NOT having a clutch and that stick in the way. That said, you get a little more control with the stick. I think if the Autobox I had was a 13 speed, I wouldn't want to go back to a stick but maybe. I do know this much. Auto's are not going away, and they are getting better and better with each year. They just make more sense fatigue wise in traffic....

[SEBOAM]

I have been driving for 15 years and the company I work for gave me a new volvo last year with the I shift. I love it.I get to drink my coffee and never put it down.I can hear the grumbling now but I do aprox 120 stops over 5 days .I also get 7.8 to 7.9 mpg with a double bunk truck.The truck may not be the best fit and finish but the service and the costs to the owner are are good.