Downshifting and turning with 80k pounds

I don't think he meant taking a turn at 40 mph. I think he's asking if he's doing 40, what gear and what speed should he be down to for the turn. That's how I took it at least.

For the OP, in the city I always take 4th in the majority of turns. 9 or 10 speed.

 

Obviously you've never overheated your brakes. Downshifting is an extremely important part of controlling your slow down. Lets say you start coasting along at 40, and someone pulls out in from of you or jams on brakes... You're not gonna press the brakes hard and magically stop in time. You're not gonna magically find your gear in a split second either, therefore, you are NOT in control of the truck, sure you are in control of the steering wheel, but that is only part of the equation.

 

1. Depends on your truck's engine and transmission. With a big 600hp engine and an 18spd you can start out in higher gears. There's really no single answer that fits all situations. Starting out in higher gears requires slipping the clutch more. If the truck is jumping while trying to slip the clutch, then you're starting in too high a gear.
2. Again what transmission are you using? 10th gear in an 18spd, 13spd, or 10spd? What speed is the ramp rated at? If that ramp has a big yellow/black sign that says 30mph you better be sure you're darn close to that, and 10th gear with a 10spd is not going work out so well. 10th gear in an 18spd may suffice.
3. Good turning gear is the one that will allow you the proper speed to safely and smoothly make the turn. One other component to this is your trailer. I drag a 40' end-dump with a 10' spread/lift axle. For turns I must lift the axle, thus putting a lot of weight on the rear-most axle/tires. It also takes away from the stability of the trailer, since there is less tire area contacting the pavement. I don't think I've ever considered making a turn at any speed greater than 15 mph. I have a 13spd transmission, most of the time the highest gear to make a turn is 4th.

Concentrate on completing the turn smoothly and safely, not how fast. When turning you're going to cause wear to those rear tandem tires. They will be sliding/skidding, not rolling forward as your steer tires do. This is unavoidable, but making turns slower can help to minimize that wear.

One more very, very important thing to consider is the road surface, especially this time of year. If you're on a slippery surface, than you better be in a lower gear, moving very slow. The trailer will push that tractor, causing your steer tires to break traction, and just shove you in a straight line with the trailer. Just this past week I delivered salt to a DOT facility. It was located on a sand road, and the entrance was slimy mud. I was only moving 5 mph to make the turn, and the trailer kept pushing the tractor. Had I been in a higher gear, I would of been in the ditch. The same can happen on a city street, downhill grade and the pavement is wet. You start into the turn too fast and your going wish you hadn't. Once that trailer tries to take control away from you, it's a fight to regain it.

 

I am new, and when I was in school, I did exactly what you do. And I don't think I ever coasted more than half again the length of my truck. Some instructors said you should never coast; others said no more than about the length of the truck.

 

I call BS. Controlling your truck involves driving it in a manner that doesn't heat your brakes to the point that you can't bring the truck to a full stop with service brakes alone. And it also involves anticipating other drivers' irrational actions, as well as driving at a speed and following distance that makes panic stops unnecessary.

Also you say that you're not going to 'magically find your gear' in time if you're coasting. So how are you going to 'magically find your gears' while you're downshifting during a panic stop? Are you going to lift your foot from the brake to apply throttle and double clutch to grab that next lower gear? No, you're not.

There's nothing magical about finding the right gear. I've only got 9 months in, and I can always grab the gear I need at any time - most times without even glancing at the speedometer.

Again, I'm with BW on this one.

edit: Maybe you're one of those drivers that doesn't start slowing down until you hit the beginning of the ramp. I'm not one of those. Depending on the grade and length of the ramp, I may be as slow as 30mph and in 8th gear by the time I'm off the highway. In town, I'm looking ahead to the next traffic light, watching the traffic and crosswalk timers, and controlling my speed so that I never have to use my brakes before I get through the next intersection. The only time I'm ever coasting is when I'm in gear with the clutch engaged, and that's only after I've downshifted to 7th, 8th or 9th AND if I'm anticipating a complete stop.

 

Taking a 90 degree turn in a 9 speed, I would generally downshift and slow to about 15-13 miles per hour to 4th gear and slightly power through it at the apex of the turn like Otter said. Now I have the 13 speed so 5thLo at 20 miles per hour, braking down to about 17-15 will work for those same turns without lugging the engine down (low RPM's) that would happen in 5th gear (Hi) with the 9 speed.

I generally always start off in LO gear and work through all the gears. This I believe is gentler on the transmission and clutch. I attended Motor Transport Driving School in the Marine Corps, one of the golden rules we were taught was to avoid touching the clutch unless changing gears. I recall in school our platoon Marines was driving down a steep dirt road in the old Jeeps with little trailers, we were instructed to put it in 1st gear at the top and leave the clutch alone, well one guy had it in either 2nd gear or just freaked out and touched the clutch, well he beat us all down the hill and rolled his Jeep.

Approaching an offramp. I'm a little bit torn on this one because at once I've always been taught that we on the road are not allowed to affect traffic behind us ie. slowing down for the offramp like when there is no deceleration lane, but also knowing the truck cannot often slow down enough in the short space of and offramp from 55 to a stop or slow roll as may be required at the bottom. My mentor always told me I was too aggressive exiting the offramps. Now I just do what I call a 'judgement call', knowing what is behind me, making a good signal in plenty of time so they know my intentions of getting off and slowing appropriately, or if no one is behind me doing the slowing that is required for the exit as necessary.

There is a pace and rhythm to operating these heavy vehicles. When I started out I did everything slower than necessary, did a whole lot of getting out to look til I got familiar with what that trailer was doing back there like when leaving a parking spot or turning sharp out of a fuel island etc, I was concerned about tail swing. Build up your confidence, trust in your equipment, but don't push it to the limit like some of these guys do out there, trying to 'show you how it's done son' attitude.

 

We were taught to drive our truck with safety in mind, and let everyone behind you deal with it. Don't worry about the traffic behind you; they have other lanes to use if they don't like how fast you're going.

 

well windsmith, your inexperience is showing. ##### happens out here, and "driving in a manner that doesent overheat your brakes" is an ideal situation. and if you can predict EVERY MOVE that other vehicles are gonna make, rational or irrational, you should be playing the lottery. Are you telling me that NOBODY has ever cut you off, or pulled out in front of you when they shouldnt have??? if thats the case, you've been driving in a bubble.

Also you say that you're not going to 'magically find your gear' in time if you're coasting. So how are you going to 'magically find your gears' while you're downshifting during a panic stop? Are you going to lift your foot from the brake to apply throttle and double clutch to grab that next lower gear? No, you're not.

you're showing your inexperience again, dont worry, you'll figure it out for yourself eventually.... who double clutches in a panic stop?? NO, I DONT LIFT MY FOOT FROM THE BRAKE... it takes a little time to figure out, but you CAN VERY EASILY use the ball of your foot to brake, while angling your heel sideways to blip the throttle to raise the rpms so you can downshift, thus, never removing your foot from the brake... I can slow down quick, fast, and in a hurry doing it this way.

There's nothing magical about finding the right gear. I've only got 9 months in, and I can always grab the gear I need at any time - most times without even glancing at the speedometer.

Good for you, let me know what happens when someone pulls out in front of you from a side street and you're coasting your truck at 40+ mph, i'm sure you can INSTANTLY pop the transmission into the right gear in the split second that you need to start slowing down. After all, thats what my comments are referencing, was going from COASTING to panic braking.

edit: Maybe you're one of those drivers that doesn't start slowing down until you hit the beginning of the ramp. I'm not one of those. Depending on the grade and length of the ramp, I may be as slow as 30mph and in 8th gear by the time I'm off the highway. In town, I'm looking ahead to the next traffic light, watching the traffic and crosswalk timers, and controlling my speed so that I never have to use my brakes before I get through the next intersection. The only time I'm ever coasting is when I'm in gear with the clutch engaged, and that's only after I've downshifted to 7th, 8th or 9th AND if I'm anticipating a complete stop.

Thats fantastic windsmith, you're cautious, but again, ##### happens.... and i'm talking about coasting in NEUTRAL, coasting while still in gear is NOT AT ALL what I was referencing here.

 

Well, once again this is turning into a "urinating contest" (filters won't let me use the correct term)...the OP is asking legitimate questions that every newbie in truck school asks....simply because driving a car and driving a big rig are different....he is accustomed to, and thinking like a 4 wheeler, regarding speed and turns.

Imagine this: There are 20 drivers sitting at the coffee clutch counter...guess what...two of them will not agree on how to accomplish any given scenario.

Just offer your point of view on the original question/scenario...and let the OP decide or try what he will.......

 

I take off in low loaded and 1stI if im empty. I have a 13coil speed.

I couldn't imagine taking off in higher gears unless its on the down side of the hill. I like my clutch and driveling the way it is.