So this is what I've gathered to correctly upshift & downshift a semi.

1st, the pedal on the right is the accelerator. Throttle is also acceptable, although not technically the correct terminology on a diesel. Gas is a state of matter (liquid, solid, gas). Gasoline is what you use as fuel in most cars. Diesel is the fuel used in most trucks. When it is time to fill up, say you need to get fuel. And since I'm ranting... a "motor" converts electricity into rotational motion -- it isn't another term for the engine under your hood...

nitpicky lecture over...

As to your questions, when starting out I rarely press the accelerator until the clutch pedal is completely released. When I do 'slip the clutch' it is when I'm starting out in a higher gear in order to clear a busy intersection quickly. In doing so, I am knowingly trading the life of the clutch disk for a little better acceleration off the line. For you, in school, this shouldn't come up...

You're doing fine. Clutch in, shifter to neutral, clutch out, accelerator to proper rpm (pretty much skip this step on upshift), clutch in, shift to next gear, clutch out... The only real trick is to remember not to push the clutch to the floor (something you do only when completely stopped) -- just push it in enough to disengage the disc.

I think you have it, but just to be clear, the second clutch action happens only once. its 'double clutching' because you use the clutch once to get out of gear, and a second time to get into the next gear...

When starting out, dont try to do too much at once. If you need to slow down, brake, pause braking & downshift, resume braking... Once you get the coordination down and have some experience you can try braking while downshifting (either heal & toe downshifting if you prefer to double clutch, or left foot braking if you prefer to float)

Good luck!

 

Thanks Double Yellow, this break down helps me as a rookie driver. Double clutching is the hardest thing for me so far. I drove a manual for 15 years and old habits are hard to break. I just had trouble not pushing the clutch all the way when I shift. The hardest thing for me is to just barely push the clutch to shift. When I did shift correctly it shifts so smoothly that if feels like I missed the gear.

My advice for Gear Jammer is to actually try to not think and worry about about it so much and try to relax and just do what your trainer says. It is easier said than done, but its the best piece of advice I can give you.

Just remember slow and smooth. Seems to be the key to driving a truck.

 

That's the best advice you can get. Just take your time, learn the procedure step by step, and perform it step by step. The most common mistakes students make are rushing their timing and missing a step, resulting in excessive grinding and missed gears. The two techniques that will save your hide while learning are recovering a missed gear and idling into a gear. Way more useful than what they call bump and run. The first two will help you pass your road test, the third will cause you to fail.

 

You should never "slip the clutch" in a heavy truck unless it is absolutely necessary (an example would be starting a heavy load on a steep grade when the truck is geared too fast, although, you should avoid these situations generally).

Heavy truck clutches are not made to slip, they are made to grab, and it does wear the clutch badly when you slip it. You should be selecting a low enough gear to start the truck without having to touch the throttle until the clutch is fully released.

Regarding up shifting, it's a relatively simple procedure to explain, but, takes practice to get good at. It's not entirely accurate to break it down into "steps", as, it should become a fluid motion. When you begin it will be a series of steps, but, as you get practiced at it, it will become a more fluid motion rather than a progression of a.), b.), c.), etc. When you engage the clutch, pulling it out of gear shouldn't be a matter of even a second, it should almost be (though not quite) concurrent with you engaging the clutch. Your time spent in neutral is all about timing. Unlike a car or a pickup, a heavy truck transmission is not synchronized, meaning you CANNOT simply floor the clutch to get it into the next gear. You, not the vehicle, has to time things. Transmissions and engines react differently, so every truck shifts a little differently.

Regarding down-shifting, it's the same process, in reverse, except when you go into neutral you'll "blip" the throttle. How hard you are going to have to stab the throttle is also going to vary from truck to truck. Some trucks have a very stiff throttle spring, other's, almost none. The stiffer the throttle, the harder you'll be "tapping" the throttle to bring the RPMs up.

The only time I touch my brakes when I'm downshifting is if the light goes red or something happens in front of me where getting stopped is more important that getting the truck into gear.

The range change is actually a matter of debate, for some. A lot of guys are taught to "pre-select" when using the range change. This means you flip the switch up or down (depending on whether you're upshifting or down-shifting, respectively), and then go into neutral. The transmission will not shift the range until it passes through neutral, so, until you pull the truck out of gear, if you are in 5th on the low-side, it will not up-shift the range until you up-shift the transmission. HOWEVER, I do not really "pre-select" when I'm shifting the range-change. I flip the range basically right as I shift. Its simply the way I was taught.

Another thing to understand about the clutch in a heavy truck versus is a car is that you DO NOT engage that clutch fully when you are shifting. You only engage the clutch far enough for the transmission to go in and out of gear. Because heavy truck transmissions are not synchronized they feature what is called a "clutch brake". It's a device that slows the transmission down when the clutch is fully engaged. You will use this to put the transmission into gear when getting started. A transmission is still turning when in neutral, and to get it in gear you must slow the rotation of the gears. Engaging the clutch brake achieves this purpose. HOWEVER, engaging the clutch brake (flooring the clutch pedal) at speed is a good way to destroy the clutch brake. So, DO NOT fully engage the clutch when you are shifting, you'll tear up the clutch brake. Only enough to go in and out of gear.

As a matter of simplicity, leave the jake off when shifting until you get good enough at it to handle it with the jake engaged, if ever. Some drivers never turn the jake on when shifting.

Shifting, more than anything, is a matter of practice. Your first month of driving a truck will be a circus of bad shifts. You'll pick up up-shifting faster than down-shifting, up-shifting is simpler, the coordination between foot, arm, and brain is less complex than on a down-shift.

Practice, practice, practice.

 

Both responses were great imo. I've been driving now for about 9 months, so for what its worth just relax. The shifting will come and by time you are out of training you will have it down. Somebody might say that I am minimizing it, but you really can and probably will overthink a lot of things. Shifting being one of those things. The comment abot fluidity vs a to b to c is right on. I float, keep the Jake's engaged all the time and really never touch the brake unil the final few feet before stopping. The Jake's jacked me up during training at first and my finisher would reach over and turn them off....lol. But as you become more fluid and youf timing becomes second nature you will just go up and down the tree without a thought or glance at the Speedo.

 

Oh and like the other responses, DO NOT slip the clutch. These trucks have more than enough power to pull out without stalling as you ease off the clutch provided you are in a low enough gear vs weight. In 9 months I've only had to feather the throttle once and that was starting from a stop on a steep upgrade weighing in at 79300. (Like Colorado referenced)

 

All great advice. Just relax and listen to your trainer. Know that you WILL grind gears and miss shifts, after more than 600,000 miles I stilll do on occasion. Biggest bit of advice...ask lots of questions about everything. You are paying good money. Get what you are paying for!

 

If you (or your instructor) ever feel like you are getting too rough with your shifting, try holding the shift knob with just the tips of your thumb, index, and middle fingers -- it can help you feel what's going on inside the transmission a lot better than when you're doing white knuckled bench-press motions.