A stupid lorry related question....

A stupid lorry related question....

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Discussion

croakey

Original Poster:

1,193 posts

189 months

Friday 10th August 2012
quotequote all
Now i know NOTHING about HGVs in the slighest

But on a drive back from the 'rents the other evening i noticed that not all HGV's are the same - so heres the stupid question.

Why are some tractor units taller than others? and why do some appear to have larger tyres (higher ride height) and some have rather small tyres (and obviously a lower ride height)

Stupid question i know - but at least i'll know the answer

iva cosworth

44,044 posts

164 months

Friday 10th August 2012
quotequote all
I drive a small HGV but don't really know for sure but at a guess probably

depends on what its maximum GVW ,gross vehicle weight it is.smile

I have noticed car transporters run quite low,probably so that they can get 3 layers

of cars on top.

Nickyboy

6,700 posts

235 months

Friday 10th August 2012
quotequote all
I'm assuming you mean like this



Compared to this?

http://www.flickr.com/photos/kenjonbro/5589620178/

Mainly due to the 4m height restriction in Europe although some UK operators use them for maximum space when carrying light cargo

chilistrucker

4,541 posts

152 months

Saturday 11th August 2012
quotequote all
croakey said:
Now i know NOTHING about HGVs in the slighest

But on a drive back from the 'rents the other evening i noticed that not all HGV's are the same - so heres the stupid question.

Why are some tractor units taller than others? and why do some appear to have larger tyres (higher ride height) and some have rather small tyres (and obviously a lower ride height)

Stupid question i know - but at least i'll know the answer
with tractor units, its about internal height and spec normally.
alot of big fleets, will spec fleet type motors as we call them, no frills, just kind of get the job done motors, as very rarely will drivers do nights out in them.
other firms, whos drivers may spend a few nights away a week, or even longer, may spec a flagship type of truck, with a wider cab, and higher too, with much more internal space, for maybe 2 beds, extra lockers and storage space, as well as extras like fridges, microwaves and the like.
we do long periods away on the tour work, so have the top spec dafs, known as super space cabs. i'm 6 ft 1, but can easily stand in mine and get dressed in the mornings smile

i don't know if other truck drivers agree, but it seems to me these days, that most trucks makers have 3 basic size variations on tractor units, small, medium and large basically.

as for wheels, again its all about space. we run the low ride setup, as most of our trailers cube out, (fill up) before they max on on permitted weight. so as the max height in europe is 4m, we have low ride tractor units and trailers so we can pull a higher taller trailer to increase cube smile if that makes sense.

4key

10,782 posts

149 months

Saturday 11th August 2012
quotequote all
Agreed, theres lots of variations of cabs for lots of variations of work. Most supermarket chains and the royal mail seem to use cheap low spec day cabs as their drivers dont sleep in the vehicles, they will have a day driver and a night driver on each vehicle.

Europe has different weight and height regulations to the uk so they only have 4 wheeled units with low profile tyres to keep the height down. Bulk tippers will have the suspension jacked up a bit to aide with ground clearance but will probably have smaller lighter cabs because they are paid on the weight that they deliver.

Most uk vehicles will have fiberglass wind deflectors on them to help with the aerodynamics because the trailers are higher than the units, where as tankers try to keep the unit low as they have ti drive under silos to load the tanks from the top.

philmots

4,631 posts

261 months

Saturday 11th August 2012
quotequote all
I'm on supermarket work and all our cabs are sleeper.

Volvo FM Globetrotter, they're full width but not as tall. Not cheapies either, 450/460hp.

I've noticed Malcoms and Stobarts are using them now too as well as the more popular and taller FH.

croakey

Original Poster:

1,193 posts

189 months

Monday 13th August 2012
quotequote all
Thank you gentlemen - appreciated (now I'm going to bore everyone I know with this information)

Amused2death

2,493 posts

197 months

Monday 13th August 2012
quotequote all
Some firms have sleeper cabs even though they will never be used to sleep in as it gives a better resale price further down the line.

double d racing

306 posts

199 months

Sunday 19th August 2012
quotequote all
Hi
does anybody know what is involved in converting current (22.5inch I think ) wheels and tyres to the low ride type ( as per continental ) I realise that you can simply buy new wheels and tyres but what else needs to be done?
Presumably tacho needs re calibrating?
What about the speedo?
anything else mechanically or electronically needs doing ?
Many thanks in advance

David
Double D Racing

4key

10,782 posts

149 months

Sunday 19th August 2012
quotequote all
Significantly smaller circumference wheels will need more revolutions at a set speed, change the differential aswell otherwise I think that you will be hitting the rev limiter before you hit 60mph.. I am just thinking aloud though smile


Thinking about it, the correct ratio diff would alleviate the need for any tacho/limiter related modifications if that runs off of the gearbox, so that is probably how it is done, they may run off of abs sensors though.

Edited by 4key on Sunday 19th August 12:10


Edited by 4key on Sunday 19th August 12:12

AF1

309 posts

203 months

Sunday 19th August 2012
quotequote all
4key said:
Significantly smaller circumference wheels will need more revolutions at a set speed, change the differential aswell otherwise I think that you will be hitting the rev limiter before you hit 60mph.. I am just thinking aloud though smile


Thinking about it, the correct ratio diff would alleviate the need for any tacho/limiter related modifications if that runs off of the gearbox, so that is probably how it is done, they may run off of abs sensors though.

Edited by 4key on Sunday 19th August 12:10


Edited by 4key on Sunday 19th August 12:12
Tacho would still need to be calibrated as the L factor would change, also the tyre size is recorded on the calibration plaque.

powerstroke

10,283 posts

161 months

Tuesday 21st August 2012
quotequote all
AF1 said:
4key said:
Significantly smaller circumference wheels will need more revolutions at a set speed, change the differential aswell otherwise I think that you will be hitting the rev limiter before you hit 60mph.. I am just thinking aloud though smile


Thinking about it, the correct ratio diff would alleviate the need for any tacho/limiter related modifications if that runs off of the gearbox, so that is probably how it is done, they may run off of abs sensors though.

Edited by 4key on Sunday 19th August 12:10


Edited by 4key on Sunday 19th August 12:12
Tacho would still need to be calibrated as the L factor would change, also the tyre size is recorded on the calibration plaque.
Yes and a notifiable alteration for DVLA/VOSA ministry plate change...