Unladen HGV acceleration?

[lufbramatt]

Random thought this morning as I watched an artic tractor unit with no trailer get away quite sharply from a set of traffic lights. I know some tractor units can be specced with 500-600+ bhp engines, and they weigh about 6.5 tons, so the power to weight is getting close to a normal car. But they have loads of gears to get through and a low RPM limit. What sort of acceleration can they achieve completely unladen? i.e. 0-50 mph?

[Trevor450]

Not sure, but you can happily block change up the gearbox when unladen. You only need all those gears when fully loaded.

[Otispunkmeyer]

As mentioned, pretty swift without a load. You can skip change as well so no need to go through all the gears. For me it's not the power...it's the torque, they might only have 400-500 hp for a near 7 ton vehicle but those engines are putting out immense torque. Merc OM471 euro 6 13 liter diesel knocks out 2500 Nm at not much over 1000 rpm and the gearing will be amplifying that at the wheels. Like putting short gearing in a car.

[kambites]

Judging by the numbers, I'd imagine they could hit the limiter in about 10 seconds.

[Halmyre]

My dad reckoned a Volvo F12 unit (no trailer) could give a few cars a run for their money in the traffic light drag race back in the day.

[R8Steve]

I had the same thought the other week when my dad was in the car with me.

An unladen, presumably V8 by the sound of it, artic pulled up alongside us at the traffic lights. I’m normally pretty swift away from the lights but this thing was off and pulling away fast before I’d even go round to putting it in gear!

I remember saying to my dad ‘jings, those things can move without a trailer on!’

Sounded surprisingly good as well!

[V10 SPM]

It is rumoured that the Tesla Semi can do 0-60mph in around 5 seconds.

https://www.youtube.com/watch?v=dOiI0yChkiI

[grumpy52]

I used to run artic units to the service place back in the 90s , not strictly legal at times with my limit of 7.5t .
All Scania 113/143 or Volvo FH units .
I can confirm that they fly !
We had one Scania 143 that had been uprated and has tachographs showing over 100mph loaded , driving that as a unit only , the only restrictions were how fast you could change gears .
In the past race trucks were as quick as Sierra Cosworths on track, up to the 100mph limit that trucks run .
I did get a go in a Volvo/white road boss race truck ,1700bhp % 2000lbs ft of torque , that was a mind bending experience.

[Nickyboy]

I made the mistake once of pulling out to overtake a tractor unit after we set off from some lights, i was in a transit and i got half way past it it showed me a clean set of wheels