Am I going to wreck the clutch/gearbox?

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
1

Hey there, trucking gods :sunglasses:

I’m a new driver (to HGV that is), passed my Cat C in the last month, and been driving the company vehicle for a couple of weeks now.

I have a question…

The vehicle is a brand new DAF LF, fitted with engine braking and (I assume like most modern vehicles) a synchromesh gearbox. The vehicle handbook specifically states that using the engine braking where possible will seriously improve the life of the service brakes, makes sense. But am I doing it properly?

For example, I’ve become quite fond of the engine braking button now, and usually switch it on after the engine’s started and leave it on until shutdown.

My real question is, am I abusing the clutch and/or gearbox by using the following technique… Let’s say I’m driving along a dual carriageway (at 50 mph of course!) and I’m approaching a roundabout. My current way of doing things is (it’s a 6 speed, like a van), off the gas so the engine braking becomes active, I let the speed drop to about 45 ish, then drop to 5th gear, and come completely off the clutch so the revs jump up to nearly the blue zone, then at about 35-40, I’ll drop it to 4th, which puts the revs in the blue zone, and leave it there all the way down until the engine braking disengages once the revs have dropped to below the green band, all the while applying gentle service brakes as necessary to achieve a smooth deceleration.

Should I be matching the revs before clutching out? Or on these gearboxes is it fine, once off the gas, to simply clutch in, drop the gear, then clutch out, resulting in a large jump in revs, meaning little delay in getting effective engine braking going?

May seem a silly question, but I mentioned the vehicle is brand new because it is effectively ‘mine’, I’m the only one driving it and, provided I stay with the company, will be driving it for the next five years. I’m genuinely not worried about getting blame placed on me, I want to look after it and make sure I’m not abusing it, after all it cost my company a lot of money to purchase, given we’re not a huge business!

Cheers people :slight_smile:

2

One note of warning is that excessive engine braking is bad if the road is slippery. In rain, ice, snow etc I’d only use it (and only with caution) if there’s a good load on the back axle.

3

I’d say you’re fine doing what you are now. Those vehicles are designed to stand up to abuse and are very tough, so a conscientious fellow like you won’t cause it any problems!

Well done for caring about your vehicle and driving style, plus not being afraid to ask!

4

The engine braking feature just sounds like it’s the exhaust brake linked to the accelerator instead of being a seperate control.I think what you’re describing is sequential downshifts which is the best way to get the most efficient engine braking on the approach when slowing down and also puts less stress through the driveline and transmission and matching the road and engine speed during downshifts is also part of that.

5

On any manual truck you should always match your engine revs to the gear selected, Basics really :wink: :wink:

6

Oh no :frowning:

7

tootman318:
On any manual truck you should always match your engine revs to the gear selected, Basics really :wink: :wink:

Sorry what year is it again? Think you’ll find that you no longer need to do that on a modern synchromesh gearbox, reving in between gear changes is a waste of fuel… Do you even drive a manual lorry?

8

Thanks for the swift replies :slight_smile:

Yeah this is exactly what I’m getting at I guess… With a modern gearbox, is it better to just clutch off and let the synchros do the work (putting more stress on the drivetrain etc), or match the roadspeed first (but risk inadvertent slipping while doing it). Obviously if done properly it feels smooth when matching the roadspeed, but we’re only human and over a year, that’s got to count for some slippage?!

Carryfast, it’s an exhaust brake yeah! The button just switches it between ‘active and’ ‘not active’ at throttle idle I guess! :slight_smile:

9

Saaamon:

tootman318:
On any manual truck you should always match your engine revs to the gear selected, Basics really :wink: :wink:

Sorry what year is it again? Think you’ll find that you no longer need to do that on a modern synchromesh gearbox, reving in between gear changes is a waste of fuel… Do you even drive a manual lorry?

There’s nothing ‘modern’ about synchro boxes they’ve been available for years.The fact is the more of a mis match between road and engine speed the more stress the synchros are put under.That’s in addition to the extra stress that’s put through the drivetrain as a whole assuming you just force the downshift through with the engine at idle and then just let the clutch back in. :open_mouth: :unamused:

10

To make good use of the engine brake you have to go down the gears earlier than say in a car so the only way you can match the road and engine speed is to rev in between gears which you don’t need to do nowadays (if you use the clutch)… But of course you shouldn’t be rough with it by dropping the clutch causing the revs to fly round suddenly, just slowly out with the clutch…

You could consider just backing off the throttle earlier and just letting the speed drop off on its own, I personally wouldnt keep using high revs unless I was very heavy. The only time I tend to let the revs go into the blue is if im on a long downhill stretch.

11

Carryfast:

Saaamon:

tootman318:
On any manual truck you should always match your engine revs to the gear selected, Basics really :wink: :wink:

Sorry what year is it again? Think you’ll find that you no longer need to do that on a modern synchromesh gearbox, reving in between gear changes is a waste of fuel… Do you even drive a manual lorry?

There’s nothing ‘modern’ about synchro boxes they’ve been available for years.The fact is the more of a mis match between road and engine speed the more stress the synchros are put under.That’s in addition to the extra stress that’s put through the drivetrain as a whole assuming you just force the downshift through with the engine at idle and then just let the clutch back in. :open_mouth: :unamused:

Im well aware that they’ve been around for a while now… So are you trying to say we should be reving in between downshifts then?

12

Saaamon:

Carryfast:

Saaamon:

tootman318:
On any manual truck you should always match your engine revs to the gear selected, Basics really :wink: :wink:

Sorry what year is it again? Think you’ll find that you no longer need to do that on a modern synchromesh gearbox, reving in between gear changes is a waste of fuel… Do you even drive a manual lorry?

There’s nothing ‘modern’ about synchro boxes they’ve been available for years.The fact is the more of a mis match between road and engine speed the more stress the synchros are put under.That’s in addition to the extra stress that’s put through the drivetrain as a whole assuming you just force the downshift through with the engine at idle and then just let the clutch back in. :open_mouth: :unamused:

Im well aware that they’ve been around for a while now… So are you trying to say we should be reving in between downshifts then?

I do because I used to drive a Scania V8. You had to rev them on the upshift too between 2nd and 3rd, or you weren’t a proper driver.

Seriously though, every automated gearbox I’ve used does it also.

13

Saaamon:

Carryfast:

Saaamon:

tootman318:
On any manual truck you should always match your engine revs to the gear selected, Basics really :wink: :wink:

Sorry what year is it again? Think you’ll find that you no longer need to do that on a modern synchromesh gearbox, reving in between gear changes is a waste of fuel… Do you even drive a manual lorry?

There’s nothing ‘modern’ about synchro boxes they’ve been available for years.The fact is the more of a mis match between road and engine speed the more stress the synchros are put under.That’s in addition to the extra stress that’s put through the drivetrain as a whole assuming you just force the downshift through with the engine at idle and then just let the clutch back in. :open_mouth: :unamused:

Im well aware that they’ve been around for a while now… So are you trying to say we should be reving in between downshifts then?

Well the Volvo i-shift does and that’s supposed to be a ■■■■ sight smarter than us drivers.

Go figure.

14

Sidevalve:

Saaamon:

Carryfast:

Saaamon:

tootman318:
On any manual truck you should always match your engine revs to the gear selected, Basics really :wink: :wink:

Sorry what year is it again? Think you’ll find that you no longer need to do that on a modern synchromesh gearbox, reving in between gear changes is a waste of fuel… Do you even drive a manual lorry?

There’s nothing ‘modern’ about synchro boxes they’ve been available for years.The fact is the more of a mis match between road and engine speed the more stress the synchros are put under.That’s in addition to the extra stress that’s put through the drivetrain as a whole assuming you just force the downshift through with the engine at idle and then just let the clutch back in. :open_mouth: :unamused:

Im well aware that they’ve been around for a while now… So are you trying to say we should be reving in between downshifts then?

Well the Volvo i-shift does and that’s supposed to be a ■■■■ sight smarter than us drivers.

Go figure.

Speak for yourself.

Go figure.

15

Saaamon:
To make good use of the engine brake you have to go down the gears earlier than say in a car so the only way you can match the road and engine speed is to rev in between gears which you don’t need to do nowadays (if you use the clutch)… But of course you shouldn’t be rough with it by dropping the clutch causing the revs to fly round suddenly, just slowly out with the clutch…

You could consider just backing off the throttle earlier and just letting the speed drop off on its own, I personally wouldnt keep using high revs unless I was very heavy. The only time I tend to let the revs go into the blue is if im on a long downhill stretch.

What he said, I leave the engine break on all day in my scania but only let the engine rev in the blue band if I’m heavy or downhill. It won’t hurt leaving it on but there’s no need to rev the absolute ■■■■ out off it all the time when im in the blue band it sounds like the engines screaming its nuts off so i tend to do that only if needed. Release your clutch slowly for a smoother transition. Nice to hear you give a toss though dont change that attitude it’ll go along way with your employer it’s worked for me.

16

As above, always where possible match engine speed to gear being engaged, a blip on the throttle is minute cost and compensated many times over by reduced wear and tear on the clutch synchros and entire drive train…in a perfect world you’d have a constant mesh gearbox and wouldn’t need to use the clutch at all once on the move, simply match revs to gear precisely and they’d slip in seamlessly.

OP is doing the job right he’s driving a lorry like a lorry driver not a bloody car driver (this brakes to slow gears to go bollox is for car/van/bicycle drivers), well done mate, not enough take a pride.

I use my brakes as little as possible, the vehicle was supplied with an exhaust brake for a reason, it isn’t up to much they seldom are and i’d rather have a Jacob any time but its better than bugger all so it gets used as primary decelerator.

I always know when i get back to my lorry after a couple of days off (especially after a week off) that the wheels will be covered in thick brake dust.

17

I agree 2nd and 3rd can be abit notchy if you rush it on those scania box’s, once their warm providing you use them smoothly they slot in fine without any reving…

18

Saaamon:
I agree 2nd and 3rd can be abit notchy if you rush it on those scania box’s, once their warm providing you use them smoothly they slot in fine without any reving…

Bloody hell man, don’t tell everyone! I’m trying to keep the dream alive here…

19

Personaly I feel, that though you would be saving some brake wear, I would say your over using the engine brake, yes you have to put revs up mto the blue band for best results, but I think that from an effeciency point of view, you’d be better to approach junctions with minimal downshifts, using your service brakes more and keeping the revs in the green for longer. Provided you’re approaching junctions with due consideration, apart from the numpties doing their stuff around you, you should not have brake so heavy as to over use your service brakes, I would say that you should leave your engine brake on “active” as it will assists in reducing fuel use during braking at lower revs(green band).

The engine brakes most useful function is to assist the service brakes on long or steep decents, reducing the service brake effort, thus keeping them more effecient through out the decent.

Just treat your truck with respect, and it’ll look after you well, :wink:

20

Juddian:
As above, always where possible match engine speed to gear being engaged, a blip on the throttle is minute cost and compensated many times over by reduced wear and tear on the clutch synchros and entire drive train…in a perfect world you’d have a constant mesh gearbox and wouldn’t need to use the clutch at all once on the move, simply match revs to gear precisely and they’d slip in seamlessly.

OP is doing the job right he’s driving a lorry like a lorry driver not a bloody car driver (this brakes to slow gears to go bollox is for car/van/bicycle drivers), well done mate, not enough take a pride.

I use my brakes as little as possible, the vehicle was supplied with an exhaust brake for a reason, it isn’t up to much they seldom are and i’d rather have a Jacob any time but its better than bugger all so it gets used as primary decelerator.

I always know when i get back to my lorry after a couple of days off (especially after a week off) that the wheels will be covered in thick brake dust.

The world has moved on since the 70’s and the way people are taught has also moved on… Blipping is not needed and a waste of fuel, you can change gear perfectly without needing to do this if you know what gear to select and your smooth with the controls, ie bringing the throttle back on whilst your letting the clutch back out etc. Also fly by wire throttles are slower to react so you cant just blip the throttle.

I agree completely eddie and that’s exactly how I’ve been taught to drive.