Why Is Overspeed An Issue?

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
41

londonman:
I’m not a truck driver but an electronics production engineer and maybe can give one reason why the digital tachos’ behave the way that they do. It’s down to economics and/or poor basic design. As, as far as I can see, these tachos are made and designed in Europe then they will have been designed to probably be tamper proof. In order for them to be adjustable to the UK speed restrictions then there would have to be some password protected or secure mechanism that would allow any tacho to be set to the UK speed.

But that would then open up the possibility of applying the same speed settings to tachos being used on the continent. Which in turn would make law enforcement of alleged excess speed more difficult since there would be no easy way for anyone to know if the tacho had been set to the UK limits.

The alternative could be to have two different tacho types - one for the UK market and one for the home market - but if the basic design did not easily allow for this then that would explain why there is only the one variant.

Don’t know if that helps or whether I’m talking out of my rear orifice.

Great site, BTW, as it was the only place where I could find out the status of that poor Greek driver and was delighted to find that he’d been released …but still doesn’t explain why he was arrested in the first place as it was as clear a case of self-defence as I’ve ever seen. So much for Jack ‘You should be able to defend yourself without fear of prosecution’ Straws’ mouthings.

I believe Digi tachos originate from this country or Scotland ( Dundee)

All new systems have to be passed for use right accross the EU, countries may well have made there own otherwise. The software also has to meet an EU quality standard.

Main reason for overspeed being an issue, it can indicate that the wrong tyres have been fitted to the drive axles of the vehicle since its last calibration, thus affecting the LKW settings, it could also point to some kind of interference device being used in the system or on the sender unit

42

vosaguy:
I believe Digi tachos originate from this country or Scotland ( Dundee)

All new systems have to be passed for use right accross the EU, countries may well have made there own otherwise. The software also has to meet an EU quality standard.

Main reason for overspeed being an issue, it can indicate that the wrong tyres have been fitted to the drive axles of the vehicle since its last calibration, thus affecting the LKW settings, it could also point to some kind of interference device being used in the system or on the sender unit

How on earth can overspeed warnings indicate the wrong size tyres being fitted or interference with the sender unit :question: :question: :question:

Are you sure you are a vosa guy ■■?

I’ll explain my initial question and why I’m astounded at your explanation.

As the sender unit reads the revolutions of the output shaft of the gearbox, it makes absolutely no difference what size tyres, or even wheels, have been fitted.
The sender unit will inform your tacho of the rpm of the output shaft.
The tacho is calibrated to convert that rpm to km/h.
If it is calibrated to read (for example) 1,000 rpm as 90 km/h, because dif Y and tyre diameter X (as fitted when this tacho was calibrated) gives you 90 km/h at 1,000 rpm. Then whenever the output shaft is spinning at 1000 rpm, that tacho will take this as meaning your truck is travelling at 90 km/h.
Fitting larger diameter tyres would result in a speed higher than 90 km/h when the output shaft is spinning at 1000 rpm, BUT a tacho has no method to determine this, so wouldn’t give an overspeed warning.

The whole point of interference with the sender unit is to show NO movement of the vehicle, when infact it is in motion. So why on earth would interference show up as an overspeed warning :question: :question:
Unless, of course, the sender is being interfered with by someone who has no idea what they are doing.
This would, more than likely, cause an overspeed warning, when the vehicle is stationary, which would make a genuine VOSA guy suspisious.

An overspeed warning, in actual fact, is caused when the vehicle travels at 91km/h or more for 1 minute or more.

As you appear to be spouting complete nonsense as fact, I submit that you are not a VOSA guy at all.

43

If you go and get tacho set and calibrated with well worn tyres, your tacho is say calibrated to 55mph bang on…

You then go back to base and fit a brand new set of tyres on, your gearbox output shaft is still turning at the same rev, but because the rolling circumfrence of the tyre is now greater, you will be doing say 57/58mph, so tyre wear does play a minor part in this.

Early days people were putting smaller tyres on, then getting OE size fitted, VOSA soon cottoned on to this, hence tyre size now plays an important part in calibration.

44

Another thing about ‘overspeed’

Going 4 or 5 mph over on the motorway to me is not a big issue, its a pain to have it monitered yes…

BUT far more dangerous is an A road at 40mph by law, yet you can coast down a hill at 50 and nothing shown on tacho, yet in theory that is a greater overspeed offence or ‘infringemnt’ than 5mph over 55mph is… :confused: :confused: :confused:

Suppose the next step forwards will be GPS monitered Tachos… :imp:

45

Kerbdog:
Agreed. Why we are set to 90kmh instead of 60mph is a total farce. We are governed by the UK government in all aspects of law, but for some reason this one law is governed by the EU, despite everything in the UK highway code, every sign on the UK’s roads and every vehicle having MPH on the clock. If anyone is pulled for ‘overspeed’ there wouldn’t be an argument that could be withheld. It’s 60mph in this country. NOT 56mph or even 90kmh.

Well,UK doesn’t have such Law but gave the Order out to do it the EU Law along which is in KM

You are European,not British anymore. Don’t stuck your Head in Mud to don’t be involved

46

Was coming down windy hill last week in a magnum touching 60mph up pops overspeed warning then a few minutes later a workshop warning didnt see that at any other time, truck brain must think limiter is U/S and wants to go get it fixed lol, does any other make of truck do this?

47

Coddy:
If you go and get tacho set and calibrated with well worn tyres, your tacho is say calibrated to 55mph bang on…

You then go back to base and fit a brand new set of tyres on, your gearbox output shaft is still turning at the same rev, but because the rolling circumfrence of the tyre is now greater, you will be doing say 57/58mph, so tyre wear does play a minor part in this.

Early days people were putting smaller tyres on, then getting OE size fitted, VOSA soon cottoned on to this, hence tyre size now plays an important part in calibration.

But the point that Simon was making is that the extra speed caused through incorrect tyre size wouldn’t affect the tachograph readout which I believe comes from the output shaft of the gearbox, and therefore wouldn’t cause over-speed warnings.

So how would over-speed warnings be an indication of incorrect tyre size as suggested by vosaguy :confused:

48

Lovelyperson:

Kerbdog:
Agreed. Why we are set to 90kmh instead of 60mph is a total farce. We are governed by the UK government in all aspects of law, but for some reason this one law is governed by the EU, despite everything in the UK highway code, every sign on the UK’s roads and every vehicle having MPH on the clock. If anyone is pulled for ‘overspeed’ there wouldn’t be an argument that could be withheld. It’s 60mph in this country. NOT 56mph or even 90kmh.

Well,UK doesn’t have such Law but gave the Order out to do it the EU Law along which is in KM

You are European,not British anymore. Don’t stuck your Head in Mud to don’t be involved

■■■■■■■■ (no offence :laughing: ) i think you`ll find a large percentage of people in this country still consider themselves British.

49

Good point raised about the 56/60 mph issue.
We have the option of domestic regs but not the limiter speed regs - anyone know why :question:

50

ROG:
Good point raised about the 56/60 mph issue.
We have the option of domestic regs but not the limiter speed regs - anyone know why :question:

We don’t have the option of domestic regulations at all, the type of work we do will decide which regulations we work to it’s not our decision :wink:

If vehicles in the UK were limited to 60 mph wouldn’t that put them outside of the law when being driven in other EU countries ?

51

tachograph:
f vehicles in the UK were limited to 60 mph wouldn’t that put them outside of the law when being driven in other EU countries ?

TRUE - but a heck of a lot are used only in the UK

52

JB:

Lovelyperson:

Kerbdog:
Agreed. Why we are set to 90kmh instead of 60mph is a total farce. We are governed by the UK government in all aspects of law, but for some reason this one law is governed by the EU, despite everything in the UK highway code, every sign on the UK’s roads and every vehicle having MPH on the clock. If anyone is pulled for ‘overspeed’ there wouldn’t be an argument that could be withheld. It’s 60mph in this country. NOT 56mph or even 90kmh.

Well,UK doesn’t have such Law but gave the Order out to do it the EU Law along which is in KM

You are European,not British anymore. Don’t stuck your Head in Mud to don’t be involved

■■■■■■■■ (no offence :laughing: ) i think you`ll find a large percentage of people in this country still consider themselves British.

now we are opening a can of worms :smiling_imp:

  1. we are and always have been european, however that relates to the continent in which we are a part of hence there are europeans who are not in the EU
  2. define ‘british’. it is not a country therefore it is not a nationality so what does it mean to be british?

back to topic. companies may not like overspeeds but i let it run to 60 MPH downhill. its legal so ■■■■■■■■ to them. they set the schedule, not me and i have to make up for the coffee/■■■■ stop somehow :laughing: