Floating the gears question.

I never heard it called floating the gears, I just heard it called progressive shifting, the truck I drive has a 10 spd roadranger the engine shifts at 16 and 13 hundred rpms. (it is a Mercedes 4000) In a Sterling, it is an amazing workhorse of an engine.. 450 hp, great motor for a company truck. But to do the double clutch thing it is basically for timing your shifts, clutching like you would in a car would not help you in a truck, if the rpms and speed are not right it wont go in no matter what you do, I have been driving since 1979 with a couple breaks to go back to school and get a degree. I learned to hate attorneys (became a paralegal) for 10 years) now I am doing what I loved back in the truck for the last ten years. Yay!! Thinking of OTR again, I have been local for 10, the money is not there. What do you all think? Help.

 

Floating is shifting without the clutch

Progressive shifting is shifting at different rpms. For instance your in 7th gear and go up to 1300rpm, then shift to 8th and go up to 1400, then go to 9th and go up to 1500rpm then go to 10th.

Although all vehicles are different. My prostar like to stay in the lower rpms with the maxxforce engine while my detroit liked to be higher in the rpm range

 

The synchros do not have to hold up to torque they just help mesh the gears they work kind of like a clutch brake. I drove in Europe for years and 99% of transmissions in big trucks are fully synchronized. The Mercedes truck with a 15.7ltr V-8 and 500hp did just fine with the 16 speed transmission. I rarely saw a gvwr under 130,000lbs in that one. The Liebher truck crane I was around had the same transmission and was just shy of 195,000lbs without counter weights and winches.

 

The trucks you drove, were they auto or manual?

 

All manual transmissions and you have to clutch each shift. They are a 8 speed with a splitter for each gear. They usually shift a h pattern 1-4 than you push over the detent and shift 5-8. The crane had a torque converter with the manual transmission. That would help with take off and moving in tight places. Was always weird to put a manual in gear other foot on the brake and than let the clutch out and it just sit there. In the early 90's they went to electronic pneumatic transmissions (EPS) which you just had a small shifter and the transmission was shifted electronic over air. I think nowadays most of them are full automatics. When I came to this country and sat in the first truck I was in total disbelieve about the trucks. A 379 Pete was like something that was outdated in the 60s over there. We all liked the american trucks to look at, but when I had to drive one the excitement wore of quickly. Two stroke diesel, upright steering column with no adjustment, standing pedals and a clutch you needed to be build like Schwarzenegger to push.
I do miss my 8v-92 Detroit, since the sound made up for all the complains. At least it was not a twin stick.

 

I hear ya, yeah in my truck I don't use the clutch unless im starting or stopping because my truck doesnt like to double clutch or clutch at each shift. I for one love driving the hood trucks haha. I do like having a steering wheel I can tilt and telescope but I've lived with one for awhile and its not too bad.

Your 8 speed H-pattern shifting sounds like our 8 and 9 speed trucks.

 

Not quite since you do not have a high and low range selector. The h pattern are side by side instead on top of each other. Just think of a 6 speed with two extra slots for 7 and 8. I had to drive a 10 speed a while back and kept forgetting 6 gear made me feel like a rookie.

 

Oh gotchya now.

Ethan

 

oh cmon georgia overdrive is fun especially down a big hill lol j/k

 

Floating the gears in a heavy truck (well, any vehicle with a manual transmission) involves manipulation of the throttle. It's difficult to describe completely as it's partially based on feel and rhythm. The basic gist is once you reach the desired RPM for a shift you let of the throttle (I don't really "dump" off the throttle, it's a bit more nuanced than that). At this point the transmission will slide out of gear. You move to the next gear, and with proper timing it will smoothly drop into the next gear. Get back on the throttle and you've just shifted. There's always been a debate going on whether or not its "proper" technique to float or double-clutch a heavy truck. Most of the time it's whatever you're comfortable with. From what I've seen it's typically the bigger companies that will tell you to double-clutch and smaller companies tend to prefer floating.

There are certain situations that require a bit more precise and thoughtful shifting if you're going to float, primarily if you're floating gears on a downhill incline, as the drag on the transmission will cause it want to stick in gear. As many note, however, once you learn to float your gears you'll wonder why you ever used the clutch so much. It's there to start and stop, that's the way I was taught.

I tend to float the gears in my truck. Situations where I double-clutch would largely include grabbing gears on a steep inclince when I'm heavy. It's also wise to use the clutch ever so often (even just breaking it out of gear) when you're heavy to relieve the torque on the drive-train completely.

I do float the gears in my pickup. I've heard back and forth about the whole thing of floating gears on a synchronized transmission. Often the reason given for not doing it is that it will eat up the synchros, but, that being said, most people tend to forget synchronizers are a wear item in a manual transmission. In all honesty, I can't see why it would damage the system if you're doing it properly and matching RPMs. A little rubbing of the gears together isn't going to kill the transmission. What you don't want to feel is a big crunch or shock to the transmission. That means you've essentially forced the gears together and it's a good way to knock a tooth or two off.

Remember, as has been noted, that heavy truck transmissions are unsynchronized, and as such you have to match road-speed, transmission speed, and engine speed when shifting. Unlike a car or a pickup, you can't just floor the clutch and drop it into the next gear and let the synchronizers match everything up. Another reason why you NEVER floor the clutch unless in an emergency situation in a big truck is that you have what is called a clutch brake, which will slow the transmission down when at a stop so that you can get it into gear. Flooring the clutch hard, especially at speed, can damage the clutch brake. When you double-clutch a heavy truck you really only should engage the clutch as far as necessary to pull the rig out of gear. In my pickup, if I am shifting with the clutch, I will double-clutch. I know it's not necessary, but, it just doesn't feel right to floor the clutch and yank it into gear.

That being said, don't sue me if you screw up your transmission, whichever way you choose to shift.