Interesting read taken from Big Rigs 26 Feb 2016 - edited
THESE days not only are synchromesh gear boxes just as good in heavy vehicles, but the technology, even for automatics, is good enough as well.
What seems to have developed is a sort of stigma towards synchros and autos, as well this mentality that if it’s not a road ranger it’s not a real truck. These days the only trucks that really use road rangers are the American brands such as Kenworth, Freightliner, Western stars, Fords and Macks.
Even these brands though are now primarily building automatics.
The European and Asian brands such as Mercedes, Scania, Volvo, Iveco, MAN, Isuzu, Hino, Mitsubishi, DAF and most UDs have been using synchromesh for a long time.
The only real reason I can understand companies persist with the road rangers is because the non-synchromesh manual transmissions are mechanically simpler and more easily manufactured with fewer moving parts than automatic transmissions.
They require less maintenance and are also easier as well as cheaper to repair due to their mechanical simplicity.
Bit of a catch-22 if you ask me; sure, they are easier to fix but they are also easier to break.
Someone who isn’t using a road ranger properly can stuff a clutch brake in less than a day, meaning they have the potential to require a lot more frequent maintenance.
OK so now we know what a road ranger is, let’s talk about how to drive one.
A few important factors you need to know are half clutch, timing, rev range, road speed when changing gears. If you press the clutch too far you will activate the clutch brake (if fitted).
The clutch brake is there to slow down the top shaft (input) of the gear box, which is only needed when you are stopped. This feature is designed to stop the top shaft from spinning, allowing the slide gear to move along and engage without grading, meaning if stopped you can easily drop it into a starting gear.
If you activate the clutch brake by pressing the clutch too deep while driving, the top shaft cannot be slowed down due to the high speed which can cause the clutch brake to blow to pieces.
We don’t need to break the drive and instead only put weight on it and change the gears by matching the revs.
Practice this without the motor going and do so until you are brain dead, the more y drop down too far.
Revving too low or too high when changing down means the top and bottom shafts are not spinning at the same speed and will fail to mesh.
TIMING is crucial
As you depress the clutch once, you pull the gear out, on second clutch compression, you put the gear in. Count 1-2 on every change. This should be the time it takes between each gear change, don’t rush it.
Remember to hold weight on the gear stick before engaging the clutch, this way it comes out of gear at the same time as the clutch is pressed and into the next gear at the same time as the second compression. This pre-loading technique helps to eliminate room for error which occurs when trying to find gears and double pumping the clutch at the same time.
A common mistake when learning is either the hand moves faster than the foot, or the foot moves faster than the hand.
THE correct revs will vary depending on make and model but as a general guide try not to lose more than 200 rpm when changing gears.
The low gears should be changed at 1000 - 1200 rpm and the high gears changed at 1300 -1500rpm.
Drive up to 1200rpm, gear out and let revs drop to 1000rpm to drop gear in. With the high gears drive up to 1500rpm then place gear in when revs drop to 1200rpm. For beginners this is so hard to do, so as with the clutch, practise with motor on revving up to 1200rpm and letting off to 1000rpm you cannot let it drop under 1000rpm otherwise gear will not select.
ROAD speed needs to be monitored constantly. You must learn what speed the truck is doing in every gear.
You can do this slowly once you not be for everyone.
If you are thinking about getting your heavy vehicle licence do some research and find out what gearbox you will need for your particular job.
Years ago it was better to get the road ranger straight away so you never had to worry about it again (which is still true), however these days they are becoming few and far between. If you haven’t had much experience with trucks before, it might work out to your benefit to start on synchromesh and get some experience before attempting the more complicated gearbox.
You can always upgrade it later, usually at minimal cost because you are now only learning one new thing as opposed to 20.
This upgrade can even be done when attempting you next licence upgrade such as stepping up to MC.
For most, this is the preferred method as training and assessment can be completed as a competency assessment rather than another assessment with the department of transport.
Weekly we deal with students who are upgrading their HR or HC licence up to the MC class into a road ranger.
"While the above story is of interest, it does lean slightly towards getting the synchromesh over the non- synchromesh licence. In our experience we would always suggest a Road Ranger over a synchromesh licence for one reason.
- If you have an Open HR Licence you will be able to drive any type of HR - with no restrictions."
We have been training Road Rangers for over 20 years - if you're willing to put the time and effort in, its well worth it! Remember that it may take up to 15 hours or more to master the "Road Ranger" - so be patient.
Shift Training P/L