Subject:
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Re: Help building a truck
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Newsgroups:
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lugnet.technic
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Date:
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Fri, 13 Aug 2004 08:50:57 GMT
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Viewed:
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3809 times
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Good post Mark:-
"Mark Bellis" <mark.bellis@tiscali.co.uk> wrote in message
news:I2AKGz.1uzE@lugnet.com...
>
> Yes, a road-going 8-wheeler with 2 steering axles has only the 2 rear • axles
> powered. There are 8x8 trucks with all acles powered, but they are mostly • for
> military applications.
I had forgotten about that application... also there are some all terrain
cranes that are 8x8x8.
> On a lot of trucks with 2 rear axles, there is some equalistation, such • that one
> axle goes up when the other goes down. This involves the trailing ends of • the
> leaf springs on each wheel being connected to bell cranks, with a rod • running
> between the two on each side. The front bell crank points up and forwards • and
> the rear one up and backwads with the rod on both the upward pointing
arms.
This is the traditional approach, but some modern trucks and trailers use
air suspension to equalise the load between various axles. I think this
really comes into its own when you have e.g. three axles, or widely spaced
axles, and therefore a lot of weight and mechanical complexity can be
avoided. I got some way to making such a system with the lego pneumatic
elements, it would be good to finish this!
> The 4-wheel steering on 8x4 trucks requires the second axle to turn a bit • less.
> It's about 2/3 of what the front axle does on real truck that I've seen.
The ratio depends on the distance between each of the front axles and the
centre of turning on the rear bogie. If both rear axles are equally loaded,
this will reside in the midpoint between the two rear axles. I've
illustrated the geometry here:-
http://www.genuinemodels.com/skip_lrg/steering_trig_lrg.htm
Jennifer
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Message has 1 Reply:
 | | Re: Help building a truck
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| Thanks Mark and Jennifer for the inputs. I have to now start building the model! Jennifer: I have seen your work and its impressive! I won't be anywhere close with my work. John (20 years ago, 13-Aug-04, to lugnet.technic)
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Message is in Reply To:
| | Re: Help building a truck
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| (...) Yes, a road-going 8-wheeler with 2 steering axles has only the 2 rear axles powered. There are 8x8 trucks with all acles powered, but they are mostly for military applications. On a lot of trucks with 2 rear axles, there is some equalistation, (...) (20 years ago, 11-Aug-04, to lugnet.technic)
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