Double clutching

I'm in school also and learning the whole double clutching thing. I thought it would be like driving a car...WRONG! I've gotten a little better since we started driving 4 days ago, but I still need a lot of work. It is all about timing...and forgeting about how you drive your car. Tell me if I'm wrong...cars you want to rev high, trucks you don't...cars you what to give it gas as you are releasing the clutch, trucks you don't (instructors have said to release the clutch before giving it throttle, throttling as you release the clutch as you would in a car causes bucking.

Fozzy...I'm looking forward to the rest of your post.

 

Thanks folks, I had a long day in Texas,, this will get continued tomorrow sometime... I promise!

 

OK, the coffee kicked in and I'm feeling a little less like sleeping for a week. Where'd I leave off? Oh yeah!

Upshifting as everyone finds out is EASY because you really do not have to do much of anything because as you raise the rpm to gain speed, the next thing you have to do is shift to the next higher gear... this means that the rpm has to FALL to get into the next higher gear. remember the flight of stairs example?

Now here is the textbook double clutch and how I taught people to do it and get better, there are a few silly sounding rules, but I (and more importantly the students) found that it works!

Rule #1. Talk out loud to yourself! This will feel pretty silly, but it works! The phrase for upshifts is "tap - neutral - tap - shift.
Rule #2 when your clutch moves, the shifter moves at the SAME TIME! You need to practice holding your leg up in the air and kind of dangling it over an imaginary pedal, you do not want to train yourself to rest your foot on the pedals (thats a no no). You may want to do this in the bathroom..strange yet effective, grab the plunger and that can be your shfiter.. I don't suggest talking too loud or making pretend truck noises, this may cause someone to call the people with the butterfly nets) remember to practice moving you foot and your left hand at the same time.

A great point was made in another reply about not using the accelerator when starting off in a truck! This is true!!! (in trucks after 1985 that is). The ECM will give you all the fuel you need to get started no matter how heavy and no matter how steep the grade is, you select a gear depending on your gross weight and simply come off the clutch smoothly yet deliberately and the truck will start rolling and you can then get to shifting! This is another problem for the car transmission people! This is a habit that has to be broken for the car drivers. Sometime people who have never driven a stick shift car will shy away because the trucks have so many gears in them.. this is not necessary because non shifters get to learn the truck transmissions from scratch and do not have to re-learn and break bad habits of the car transmissions!

So heres an upshift... you start off , raise the rpm (and your road speed).. we'll use 1000 rpm for clarity... it doesn't take ANY time at all to get too 1000 rpms btw. This adds a little problem as the shifts at these first few shifts must be done rather quickly! Remember, you are trying to match the wheels to the transmission to the engine. If you screw around too long, the wheels stop moving and you are trying to sync and moving engine to a moving transmission to a STOPPED wheel... not too effective nor fun. The same thing goes if you are heavy on the clutch, if your engine is turning and the wheels are rolling but your size twelve is buried to the floor.. your transmission is NOT moving.

So,, raise the rpm and when they are up around 1000, tap the clutch and move the shifter to neutral... almost instantly tap the clutch and move the shifter into the next higher gear and instantly get off the clutch! Start applying power, raise the rpm to 1100, repeat the process, ALL shifts just chant the mantra.. tap neutral, tap shift.... this will help.. This gets you UP into the gears and going faster all the time...

Speed in gears? This is another area where a little knowledge helps a new driver a lot! In an automobile there are usually thee to six gears in the transmissions. Even in the low gears, if you rev really high, you can get the car to really go fast in the lower gears. Trucks will not do this! The speed is limited in gears electronically! If first gear the highest speed you will get with you foot buried in the floor is about 4 mph! The next gear, around 6 the next? 10 or 12. The usual best gear for puttering around town in is 7th gear. this of course depends on the transmission and gearing, but generally speaking, you'll be in a higher gear than you are used to.

Tomorrow, or whenever I get some time.. downshifting and the problems therein.. maybe I'll go over a little gear recovery problems too.. I'll try not to put anyone to sleep!!!

 

Fozzy : I am only familiar with the Freightliner with an eaton transmission, and the only part of your lesson that has me confused is your reference to 1000 rpm as a shift point. In my experience, 1200 rpm is the shift point meaning you need to accerate up toward 1500 - 1700 rpm so that when you come off the gas, double (or single) clutch, the rpms drop and by the time you are in the next gear, it has matched 1200 rpm again.
Conversely, downshifting, you slow to 1000,rpm, shift into nuetral then rev up to 1200 to match the next lower gear.
I'm especially curious as tomorrow I drive a Volvo for the first time in my 12 years, and have no idea what their standard engine/tranny is so am nervous about learning the shift with a trainer evaluating me during the road test.

 

Well, 1200 is good for a start, but you really do not need to rev even that high for the shift for example from 3rd to 4th. I taught progressive shifting and the lower rpm served two purposes. first it set in the students brains that they must raise the rpm progressively higher to get to the next gear. This also allows the shifts to come quicker and not waste as much fuel on average.

Another problem is that higher rpm means that the driver is simply waiting for the rpm to come back down to get the shift in. All the while the rpm is dropping, so is the road speed. If they are really high on the rpm, their road speed could fall so low than their shift just became unnecessary because their road speed just dropped to the last gears "speed range". This is usually where the student is grinding and clutching and cussing..

I explain it like this.. If I have a rock in my hand and I want to throw it at you... but first I must toss it straight into the air, why throw the rock 50 feet in the air only to have to catch it to then throw it at you? The higher the rpm, the longer the wait, the longer the wait, the more chance of a missed shift and of course the more fuel used. The higher rpm really doesn't do anything for you at all other than waste fuel and time.

More on this later... back to work!!

 

Follow tips left by others to pass the test with time and expereince you will find that floating the gears is the best thing but that to takes practice too.

 

Basically people float gears because they are simply too lazy to do it the correct way... There is no other reason other than that it's easier.. It's not "better" in aspect. The majority of drivers do float. That still doesn't make it anything but "easier".

 

Fozzy I like the way you teach. We need more like you to show the new drivers the right way. It's gets back to my opinion that I believe driver trainers should have at least 5 years experience and it should be another endoresement on the CDL. Companies should be held accountable for making sure their program is working and fined if it is not.

Too many new drivers think that shifting without the clutch will make you a "Truck Driver" and they're the same drivers that run the engine up against the peg when they shift. A clutch is alot cheaper to replace than a transmission and you can still get long life out of the equipment if you let the truck work for you instead of letting yourself work the truck. Good job and please keep it up.

 

Thanks Gas Hauler.. This is one of the reasons that the trucks get more and more technology in them. First of all it makes life easier.. secondly it removes the Dumas factor and makes it almost impossible to drive the truck incorrectly. I know I'll sound like a old codger, but the old trucks HAD to be driven correctly. I posted the other day about a truck that I got to drive from the shop to a customer and I'm telling you that I appreciated the technological advances that we ENJOY. New drivers really do not have much of an idea of what the old trucks were nor how easy to drive they are now! I drove a Kenworth C500 with a 5X4 trans, all springs, no air ride anything, no A/C, no power steering. Now, admittedly I never had to LIVE in the old equipment, but I sure drove enough of it to realize how spoiled I am now! LOL