Speed Limiters?

[sherbertdip]

I was on the A34 heading north on the lumpy bits between Newbury and Oxford last week.

I was overtaking a line of lorries which were just getting on with work, on the last down hill stretch the foremost truck which had been leapfrogging the others a bit started to accelerate down the hill, I kept pace with him to an indicated 80mph - no porkies there!

At that point he was still accelerating so i let him go and pulled in behind him, it was a Polish registered truck, i caught him up again where on the flat he was still doing an indicated 65mph.

My question is: Do commercial vehicles have speed limiters that can be overridden?

Cheers

[richs2891]

They certainly can be removed, or it could just be "broken"

[chilistrucker]

Back in the day many of the wagons had a way of 'tampering' with the limiter.
I know scania, daf, and man for sure had ways that the limiters could be worked around :0
I'd imagine its abit harder with all of todays brand new trucks.

[GC8]

A strong magnet will overwhelm the hall effect sensor on many vehicles. I have always assumed that Polish vehicles have a limiter fitted, but some EU countries opted out: Eire, for example.

[sherbertdip]

That would explain why i was passed by an Irish truck on the outside lane of the M5 a few years ago, he wasn't hanging about either

I asked my brother in law who is a HGV driver about that, he just laughed and shrugged his shoulders say most Eire drivers are like that.

[Cyberprog]

What I've never understood, is why the limiters are set at 56. The Speed limit is 60, so why 4mph less? Boggles the mind. I know why some are set to 52 and other random numbers, that's for fuel efficiency and set by the fleet operator...

[GC8]

The EU limit is 90kph which trumps the British limit of 60mph.

[Cyberprog]

Ah, ok, makes sense then

[bigwheel]

sherbertdip said:

I was on the A34 heading north on the lumpy bits between Newbury and Oxford last week.

I was overtaking a line of lorries which were just getting on with work, on the last down hill stretch the foremost truck which had been leapfrogging the others a bit started to accelerate down the hill, I kept pace with him to an indicated 80mph - no porkies there!

At that point he was still accelerating so i let him go and pulled in behind him, it was a Polish registered truck, i caught him up again where on the flat he was still doing an indicated 65mph.

My question is: Do commercial vehicles have speed limiters that can be overridden?

Cheers

I know that road well.
The speed limiter only prevents the engine pushing the truck beyond 90 kph on the flat or uphill.
Downhill, the "Soap Box Derby" effect takes over. The weight of the truck carries it beyond 90kph and needs the driver to use the brakes, retarder and/or the exhaust brake to control the speed. The heavier the truck, the faster you can go, downhill

[StuntmanMike]

bigwheel said:

sherbertdip said:

I was on the A34 heading north on the lumpy bits between Newbury and Oxford last week.

I was overtaking a line of lorries which were just getting on with work, on the last down hill stretch the foremost truck which had been leapfrogging the others a bit started to accelerate down the hill, I kept pace with him to an indicated 80mph - no porkies there!

At that point he was still accelerating so i let him go and pulled in behind him, it was a Polish registered truck, i caught him up again where on the flat he was still doing an indicated 65mph.

My question is: Do commercial vehicles have speed limiters that can be overridden?

Cheers

I know that road well.
The speed limiter only prevents the engine pushing the truck beyond 90 kph on the flat or uphill.
Downhill, the "Soap Box Derby" effect takes over. The weight of the truck carries it beyond 90kph and needs the driver to use the brakes, retarder and/or the exhaust brake to control the speed. The heavier the truck, the faster you can go, downhill

This, an as for the Irish driver, they have had their wings clipped.

[Chipchap]

GC8 said:

The EU limit is 90kph which trumps the British limit of 60mph.

The EU legislation states [or used to] 85 km/h with a tolerance of 5 km/h. In UK we do straight to 90 km/h or 56 MPH generally. Some fleets set them lower for fuel economy.

[GC8]

I do have an HGV licence.

[Chipchap]

GC8 said:

I do have an HGV licence.

Funnily enough so do I.

[powerstroke]

Chipchap said:

GC8 said:

The EU limit is 90kph which trumps the British limit of 60mph.

The EU legislation states [or used to] 85 km/h with a tolerance of 5 km/h. In UK we do straight to 90 km/h or 56 MPH generally. Some fleets set them lower for fuel economy.

The legislation states maximum set speed not to exceed 90 KPH
Some fleets set them lower to cause congestion ,elephant racing and stress..

[grumpy52]

The old trick of having old tyres on their last re-cut when going for speed limiter calibration and then fitting nice new tyres would give a few more mph .
I understand the latest trucks use GPS links for speed limiters !

[GC8]

Really? Bummer! What about interference, lag and error?

[grumpy52]

From talking to a techie about a digicard unit that was fubar , the limiters are getting and will get more and more sophisticated .
Most are linked with the digicard units , so as the naughty boys find bypasses the boffins add more technology.
If you are really unlucky you work for a company that have a tracker system that records every indiscretion of overspeed or progress on restricted roads, they even know when a door is open.
Once when doing agency work I was phoned at the first call telling me to slow down and to turn the engine off while unloading , at the second call the battery died because the tail lift killed it , nice short trip that was .

[AF1]

grumpy52 said:

The old trick of having old tyres on their last re-cut when going for speed limiter calibration and then fitting nice new tyres would give a few more mph .
I understand the latest trucks use GPS links for speed limiters !

It's the Tacho calibration when you want to have a set of old tyres on, the speed limiter just receives a speed signal from the Tacho.

[martin mrt]

Yup, I used to get the tacho calibrated as soon as the tyres were bald whether it needed done or not, handy when you know the guy doing the calibration.

Going back to a truck that did 55/56mph after one that did 59/60mph was a bind

[GC8]

Id have been happy with one or two miles per hour more than the majority. Even that feels good and helps you get along.