Was talking to my boss today about twin-steer tractor units, and asked him why we don’t use them. He said that Volvo don’t offer one any more, and neither do Scania.
Is this so, and if so, what caused their decline in popularity- seems they were far more common 20 years ago?
Volvo haven’t for some time IIRC.
Thought Scania did ? when did they stop 
DAF do 
Scania still do.
I’m currently working for a customer on the agency, who has about 60-70 of them, a mixture of G/R420’s and G400’s, all under 2 years old. In fact the first 10 of the 39 new G400’s arrived this morning.
Ken.
Scania made a twin steer optional last year, with mid-lift standard. Previously they had only offered the light weight version non-steered.
Volvo have never offered a solid link operated twin steer, their first 6x2 was a castoring contraption which never worked well, especially in reverse, from around 1985 to 88, then they went mid-lift. Now recently you can spec a Volvo with the middle axle steered hydraulically, but its VERY expensive.
This just leaves DAF and IVECO with twin steer as standard.
Why? Cost and to a lesser degree weight. To my mind you will always get far superior tyre wear and noticeably better fuel consumption from a correctly aligned twin steer than from either a mid-lift or a tag. Do these savings outweigh the capital cost, well there’s the question.
Harry Monk:
Was talking to my boss today about twin-steer tractor units, and asked him why we don’t use them. He said that Volvo don’t offer one any more, and neither do Scania.Is this so, and if so, what caused their decline in popularity- seems they were far more common 20 years ago?
Google says that you can still find twin steer volvos:
orys:
Harry Monk:
Was talking to my boss today about twin-steer tractor units, and asked him why we don’t use them. He said that Volvo don’t offer one any more, and neither do Scania.Is this so, and if so, what caused their decline in popularity- seems they were far more common 20 years ago?
Google says that you can still find twin steer volvos:
imagine the fun you could have with that set up lol
orys:
Well, Google and Photoshop 
isnt that a pic of the cab set up from a road sweeper
Harry Monk:
orys:
Well, Google and Photoshop
I am not AS GOOD in ammending pictures… And I am using Gimp 
According to the biglorryblog, it’s an automatized waste truck and it have two wheels fitted to make it easier for the driver to drive closer to the kerb…
Also in my native town there used to be Iveco road sweeper with two wheels in it - for the same reason
Yea, probably is…
Orys, you’re good at Googling, so find me a picture of a car, in Russia, which has been converted from RHD to LHD using an extra steering wheel connected to the original by a set of pulleys… it’s out there somewhere, I just can’t find it!
You mean that:
?
Bloody hell, that was quick!
Because I knew where to look for that. On Polish motoforums it always turns up when someone asks if it’s easy to convert RHD car into LHD. This picture is a standard answer…
So all I had was to put “anglik” into google, as anglik stays for Englishman but also for a car from UK
I love the twin twin steer and the V belt steering, but the original twin steer, pushers or tags were all a compromise anyway.
A tag with the axle lifted snagged on the trailers, especially if you were pulling RTR fridges, twin steers were ok until it was slaipe and the pusher just transferred the weight like a see-saw.
I don’t see the point now of 44 tonners in the UK, when we ran at 38 tonne on 5 axles and the neighbours were running at 40t. Lets have a standard set up and go back to intermodal at 44t, and the rest at 40 tonne, Germans, Dutch and French Polish
5 axles, 24 tonne bogies & 12 tonne drive and show the frogs what compromise means…
I believe that tag axles died out when the new turning circle regs were brought in a few years back, because the trailer had to sit too far back to accommodate the tag axle.
I always preferred driving a 4x2 at 38 tonnes, any extra axle anywhere just seems to cause a new set of problems and makes the handling deteriorate…
My old man always loved his tag axle scanias and found them very manouverable (especially when reversing with the tag up). Since going onto mid lift volvos says hes never known tyre wear like it. As for fuel im sure you can get a pretty close coupling with a tag unit with a sliding 5th wheel.
The thing i do wonder about though is why tag axle units have become so long?, Scanias became longer when the change to air suspension came around, but Volvo,Daf and Man tag units are really long.
Harry Monk:
Was talking to my boss today about twin-steer tractor units, and asked him why we don’t use them. He said that Volvo don’t offer one any more, and neither do Scania.Is this so, and if so, what caused their decline in popularity- seems they were far more common 20 years ago?
Quite simply, weight and cost. A steering axle has a higher weight penalty than a non-steering one.
NB12:
The thing i do wonder about though is why tag axle units have become so long?, Scanias became longer when the change to air suspension came around, but Volvo,Daf and Man tag units are really long.
there’s no standard length/wheelbase though - depends what you spec, my latest I specced at 3.40m rather than the previous 3.05m to get lots of lovely diesel on there and a toolbox built into the tanks
Conor:
Harry Monk:
Was talking to my boss today about twin-steer tractor units, and asked him why we don’t use them. He said that Volvo don’t offer one any more, and neither do Scania.Is this so, and if so, what caused their decline in popularity- seems they were far more common 20 years ago?
Quite simply, weight and cost. A steering axle has a higher weight penalty than a non-steering one.
For a Scania it’s about 150kgs comparing a steering axle to a non steering axle on a mid-lift, but how many of you dump the air on the mid-lift (e.g. Volvo) when you are turning in a “tight” situation.