had my first lesson today with the tractor trailer

You can also practice double clutching in p/u truck with a standard transmission,you can also float gears in a p/u with a standard transmission.
Obviously not quite as many gears but you will get the general idea because floating gears in a p/u you also have to get the rpm's right for it to work.

 

the transmissions are synchronized? i was use to driving the 6 speed kenworth T300's when i got my class B CDL. i thought that transmission was synchronized. 10, 13, and 18 speeds are synchronized? then why are they harder to shift than a 6 speed?

what is the difference between synchronized and unsynchronized transmissions?

 

Synchronized transmission is one with built-in mechanisms to automatically equalize the speed of its gears with the engine rpm's to allow smooth shifting without the need to double-clutch.

 

The only part of a truck transmission (10, 13, 15 18spd etc.) that has synchronizers is the range box. Even the automated mechanicals (eaton ultashift etc.) arent synchronized; the engine's computer does the same job as a driver floating gears. There are synchronized truck transmissions like the six speed eatons in straight trucks, which are fully synchonized, and also the five speed with two speed rear end types that were quite common a few years ago, but you won't see those in much of anything larger than a 33,000 gvw straight truck. Anything the average OTR driver will deal with is a plain old run of the mill crashbox. Either double-clutch or float 'em. I prefer the latter myself.

 

Agreed, but you should tell them that there's a difference in rubbing, grinding, and banging a gear. Grinding and banging are not acceptable and you can have damage depending how hard one does it.

 

Did you know how to drive a manual shift before school Danny? I am asking because I have all my life but I don't think driving a big rig is anything like that, I mean and 18 gear, whatever. I saw a video on it but it really wasn't shot very well so I couldn't see what the guy was doing with his hand while he was double-clutching. You'll get it though. Hang in there and keep sharing your stuff because I for one, surely appreciate it. I hope to start school soon if my grant comes through

 

the video I watched showed the use of the tac, which I have not used but once or twice in my entire life. Do you always have to use the tac I wonder? Seems like I've just gotten used to "the feel" and also, keeping the truck/car at the same speed. What I mean is, when I am going up a hill in my small truck, when I start to lose speed I shift accordingly. I don't know if that makes sense but I am thinking in a big truck, when you get the "feel" of it, you'll just know when to shift without using the tac. I'm sure on the other hand, it's gonna be better for me to learn to use the tac and I am also sure I will be expected to

 

Yup, and that's why you have to double-clutch. You don't have those nifty little rings between the sliders and main shaft gears to match everything up for you. You can practice double clutching with a pickup truck or car transmission to get the rythm down but you really don't get the same effect (it won't grind when you miss a gear). As far as floating gears with a synchronized transmission, its not a good idea because with a smaller engine the operating range is too wide and most of them don't allow you to dial in the throttle precisely enough. You can do it with the six speed eatons (mated to something like a DT 466) pretty well but even then you only wind up wearing out the sychronizers faster which just puts more crud in the oil.