Rev Matching for Gear Changes

[liberace]

If you read the post from the beginning Pat, it’s CM who’s asking the initial question. Alixxx is big enough to apologise in the above post, so I think that answers your question. As for the old time transport company, their’s more than one way to skin a cat. In fact, I might just start a new thread on this as I’ve a couple of decent stories. Thanks for reminding me .

[marcustandy]

theghostofcain:
I am currently taking my C+E course. I have been told to do this when slowing down. First brake to get the speed down (revs to about 1000rpm) then lift the clutch up, at the same time increase the revs to match the speed. Then it’s back on the brake and repeat the procedure.

As far as I can tell, this is a way of getting round slowing the vehicle with the gears (which examiners don’t like), although technically that’s what you are doing.

marcustandy:
I’ve got two of my cat C+E students on test tomorrow and will get chance to chat to the examiner. I’ll canvass his opinions on this matter.

I spoke with the examiner today, ref the above. He was firmly of the opinion that any use of the throttle as described above would incur a ‘driving fault’ in ‘Controlled use of the: Accelerator’ of the Test Report.

Actually it was not a good day for me . Of my two students, the first passed with 5 driving faults ( ) and the second, who had only 1 driving fault, failed because he was 1 inch short of putting the rear of the trailer in the box . This is an exercise that he was spot on with all week (and last week when he did his cat C) but has let him down today.

It is especially frustrating for me, as out of 22 students since qualifying as a DSA Registered Instructor, he is the first to fail and so has gone my 100% record.

[cm]

Alex hi!

I for my part also apologise to you for throwing my teddy in the corner.

If I did’nt appear to understand transmissions before, thanks to all of you,

I DO NOW !!! I think!

Regards,

Charles

[paul_midway]

i fail to see how it matters

if its your own truck the you want to drive as economic as possible and reduce wear and tear as much as possible

but if its not then i dont see why anyone should be bothered how much wear is caused by doing this that or the other

just drive as you feel comfortable

i use both gears and brakes to slow me down in a truck and in car , the only time i didnt do this was on my test , the test was a long time ago… forget all that and drive however you feel is right

[spaceman]

All interesting stuff. I have this un technical feeling that a lot of it depends on the individual truck.

I’ve taken older trucks to Switzerland a few times. With ancient brakes, coming down those slopes without holding it back on the gears is a very dodgy prospect. I’m pretty sure the brakes would get too hot if you didn’t do this. So it seems sensible to dab the brakes to keep the revs below the red, and hopefully there would be enough left to pull up if needed.

And for an older truck, which changes its mind day to day on how it wants its gears changed(!), the prospect of coming down a hill and needing to change down is quite frightening. Chances are you’ll be “pudding stirring” to get any gear at all.

I’m no spanner man, but I do drive and pay the bills. I’m quite happy to forgo a bit of fuel economy in favour of knowing I can bring the thing to a halt. This idea of abusing a bit of kit because you only drive it and don’t pay the bills is very interesting. Maybe a career change, or prozac, (or both) are needed!

[marcustandy]

paul@midway:
i fail to see how it matters

if its your own truck the you want to drive as economic as possible and reduce wear and tear as much as possible

but if its not then i dont see why anyone should be bothered how much wear is caused by doing this that or the other

As a line (tpt) manager the above comment sends shivers down my spine! If I were an Owner Operator looking to employ a driver i’d be ‘having kittens’!!

spaceman:
I’m no spanner man, but I do drive and pay the bills. I’m quite happy to forgo a bit of fuel economy in favour of knowing I can bring the thing to a halt. This idea of abusing a bit of kit because you only drive it and don’t pay the bills is very interesting.

Agreed!!

spaceman:
I have this un technical feeling that a lot of it depends on the individual truck.

With ancient brakes, coming down those slopes without holding it back on the gears is a very dodgy prospect. I’m pretty sure the brakes would get too hot if you didn’t do this.

In previous replies it was pointed out that a lot of what has been mentioned is modern techniques for driving modern trucks. ‘Ancient brakes’ is indeed another matter!!

[mrflibble]

marcustandy:
:arrow: I spoke with the examiner today, ref the above. He was firmly of the opinion that any use of the throttle as described above would incur a ‘driving fault’ in ‘Controlled use of the: Accelerator’ of the Test Report.

I did my C+E last October, and double-declutched (with rev, as I described) all the downward changes (including 5-1 in the gear change exercise). I have my test report in front of me, and I have no minor faults on “controlled use of accelerator”. Gears and Steering? Yes (I forgot to drop the range change collar and tried to pull off in 8th instead of 4th , plus I wandered about in my lane on the M5 apparently). Accelerator & clutch? No.

[wheel_nut]

I reckon that you all need to understand how atruck works!

If you want to roll down a hill and rely on your brakes, you will end up in a graveyard.

If you want to roll down the same hill and rely on your gears you will end up with a knackered engine in the graveyard.

The trick is to use them both together, that is what they should teach.

you have a 400hp truck carrying 44 tonne, use them 400hp to slow your 44t

[willy_gofar]

I drive an Iveco 75E15, if you don’t keep it swinging it dies, especially on hills so when I change down going up a hill the foot stays firmly planted on the throttle and the gear shift is accomplished as quickly as possible, may annoy the purists out there but it works for me as the last thing I need is to see the speed drop off far enough to have to do another downshift.

[wheel_nut]

If an instructor is telling you that you should ‘blip’ the throttle between gearchanges, then he’s wrong. You dont and for more than 1 reason. You dont ‘blip’ the throttle before you switch off ( as you used to) and you dont rev the engine when you have just started it from cold.

Blipping the throttle before turning the engine off has nothing to do with braking, clutch wear or economy. It was not even done with a diesel engine! This was done to draw fuel into the cylinders, to aid starting by hand with a petrol engine.
If you mean leaving an engine ticking over after a long run, this aids the turbo to slow down and cool with lubrication, rather than starving the bearings of oil whike the turbo is still spinning

You dont rev the engine to warm it up when starting from cold for the same reasons because you should drive off steadily to raise the operating temperatures to correct levels.

Modern Brakes are the same as ancient brakes, when they overheat, you crash. unless you are using ceramics or kevlar.

Driving Instructors are teaching you to pass a test, they are not teaching you to drive proper trucks in the real world.