How does auto shift work in a rig

Ok, you have 4 basic styles of automatics in trucks.

First you have Allision. This type is like the one in your personal vehicle. It does have a torque convertor. You apply the brakes and hold them down when you shift into or out of drive, neutral, and reverse. It is a simple push button system. No hard work there.

The next kind that you have is Eaton Fuller automated transmissions. These are the standard transmission, but with shift solenoids where the shifter would be. These are then split up into two types. Autoshift and Ultrashift.

Autoshift has a clutch that you have to use on take off and stops. Again with these you have to release the parking brake, hold down on the service brakes, select the direction that you want to go (R for reverse, D for Drive, N for nuetral, and L for Low Range) push the button on the selector pad and the light should light up if it is in that gear direction. If it beeps at you it means that it will not go into gear and that you are doing something that it does not like. Reselect Neutral and try again. With the autoshift you must also have the clutch pushed in to put it into gear.

Now to the Ultrashift, I don't care for these that much. These have a centrifugal clutch and will not normally activate (make the truck move) until it hits around 750 rpm. This one does not have a clutch pedal. For this one you put you foot on the brake and hold it while you select the direction that you want to go. Once it is in gear the light will stay on beside the direction indicator/letters. This kind is very hard to do presice movements such as backing up 1 foot or less because it wants to go, there is no easing into it moving. The best way to back up with this kind of transmission for tight manuering is to apply slight pressure on the brake so that you can get the rpms up around 750 and then slowly release the brake so that you can better control the speed for small movements of the truck.

The last one is the Meritor auto. I do not know much about this one as I have only driven this type of transmission in a truck a handful of times. It is very similar to the Ultrashift except for the fact that it had a paddle shifter. I never did get the hang of that transmission. I doubt that the trucks your boss is looking at has that type of transmission in it.

The Allision and the Eaton Fuller Autoshift and the Ultrashift both have a manual mode on them. They either will have arrows on the panel to push for up shift and downshift or it will have a pushbutton on the side of the shifter. Yuo can put it into manual mode while going down the highway at anytime. The thing is that when you push the buttons on manual shift it is mearly a suggestion to the transmission. If you put the transmission into manual mode and the TCM sees that you are "over revving the engine" it will automatically do an upshift for you. The engine rpm has to be within a certain spec for upshift and downshifts. You can also have it in the automatic mode and use the shifter selectors to downshift or upshift as needed but again the engine rpm has to be with in a certain frame. The thing about doing it this way is that it will do the shifting for you and then you can upshift or downshift it when you think is nessecary, but it will still be in automatic mode. If yo do this and it beeps at you it is basically telling you that it will not shift into that gear because of the RPM of the engine is outside of it's shift range maybe you are running to high of and RPM and you want to downshift, you push the button, it will beep. The manual mode helps with climbing hills. If you take two identical trucks except for the tranmission, one a 13 speed Autoshift and the other an Eaton Fuller 13 speed manual trans, and have a race up a steep hill the manual trans truck will win every time. The shifts on an automated transmission take longer so yu will lose a lot of speed going up hills very fast.

Hope this helps you.

Greg

 

Between March 2001, and January 2003, I drove for a company that was 98% autoshift.
All of the trucks I drove during this time frame had a clutch, which you only used to start off with, and when you came to a stop. After you released the clutch, the transmission would shift on its own. Unless you had it in the 'hold' position. I read the other post that said it would shift even if it were in the 'hold' position, but none of the trucks I drove would.
I started off in a Volvo. It had a floor mounted shifter. You squeeze the release button and move the shifter into whatever gear you needed, such as D, or R. If you put it into the 'hold' position, you could manually change gears by pressing an up or down arrow button.
For the most part, I drove Macks. They had a swing away gearshift, that was mounted to the bottom of the seat. So, no matter how high, or low, you had the seat, the shifter was in the same spot. No trying to reach high or low to grab for it. The swing away part was pretty nifty. When you parked, you just swing the shifter bracket toward the back of the seat. Therefore, it wasn't in your way when you wanted to go back to the sleeper. It operated just like the one in the Volvo.
The Freightliner had a paddle shifter that stuck up off the steering column. It had a small button that you would slide between neutral, drive, reverse, and hold. In hold, to manually change gears, you would pull the paddle toward you to shift up, push down to shift down.
The International had a touch pad on the lower part of the dash.

Like i said, this was in the 2001 to 2003 era, and they may have drastically changed.
The purpose of 'hold' was to hold the same gear. Like, if you were going down a steep hill, and you needed to stay in one gear and use the engine brake to keep the speed down. Otherwise, you would just keep going faster, or overheating your brakes.

 

I hated having to hook up to trailers in my yard with an Ultrashift. My company had one for a few weeks as a sub unit. Once you start to get under the trailer the truck just stops. You have to hammer on the gas to get it to go under all the way. This made it very hard not to hit the pin with way more force than needed. That truck sucked and it was no fun to drive at all. Only good thing about it was when stuck in traffic on the highway... Other than that they're garbage in my opinion

 

You know what I am talking about with the go - no go with the ultrashift. It is not much fun for short movements of the truck/trailer.

 

I need help!!! Recently I was at a yard viewing trucks for sale. It was a 2006 freightliner c120. The engine was running and when I was exiting the truck my knee accidently bumped the gear shift and sent the truck in motion hitting two other parked trucks. I quickly jumped in the driver seat and pressed both the brakes and the clutch at the sametime but it failed to stop the truck right way. Now the company wants me to pay for all the damages but I can't help but feel there might have been a defect with the gear shift since it moved so easily or one of their employees did not correctly place the gear shift into place. Has anyone ever experienced anything similar? Please advise how to fight it?

 

The auto I drive has a manual option on it, allowing you to manually shift. Handy in bad weather or slow moving situations.

 

FreightLiner SmartShift is garbage
The Volvo unit is really nice

 

I have an a UltraShift MXP. It does not have a centrifugal clutch. It is has an electric servo motor that operates it. I can do as fine of a move as I want. Can even rock it some if stuck.
In manual mode the first fifty percent of the throttle works to simulate clutch operation, above that it takes off. Takes a bit of getting use to but handy when loading grain and I only have to move the truck two feet at a time.