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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Wed, 11 Aug 2004 16:58:11 GMT
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Viewed:
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3993 times
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In lugnet.technic, John Seemon wrote:
> Hi all,
>
> I am about to start building a truck. 4 axles, front 2 steered and the last
> axles will have paired set of tires. I would think that the rear axles are only
> driven. Is it the case in most trucks? Will a dump truck be like that?
>
> I need some ideas, suggestions, inspiration :) for possible suspension
> configuration and drive combinations.
>
> Any reference material, past mocs etc, ideas will be much appriciated!
>
> Thanks in advance.
>
> John
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, 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.
Using beams instead of leaf springs, actual suspension on a MOC would not be
necessary, since the rear axles will move prototypically with just the
equalistaion. This is particularly useful if the load on the rear of the truck
is heavy - heavier than a suspension system of prototypical size will cope with
(i.e. size limits the number of springs you can fit).
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. It's
achieved with a lever system. Try a 4L liftarm with the pivot on position 1,
the input from the front axle on position 4 and the output to the 2nd axle from
position 3. Many Lego MOCs use gears instead - you might try a 20:12 ratio
followed by 16:16 to get back to the same position on the chassis.
Mark
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Message has 1 Reply:
 | | Re: Help building a truck
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| Good post Mark:- "Mark Bellis" <mark.bellis@tiscali.co.uk> wrote in message news:I2AKGz.1uzE@lugnet.com... (...) axles (...) for (...) I had forgotten about that application... also there are some all terrain cranes that are 8x8x8. (...) that one (...) (20 years ago, 13-Aug-04, to lugnet.technic)
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Message is in Reply To:
| | Help building a truck
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| Hi all, I am about to start building a truck. 4 axles, front 2 steered and the last axles will have paired set of tires. I would think that the rear axles are only driven. Is it the case in most trucks? Will a dump truck be like that? I need some (...) (20 years ago, 11-Aug-04, to lugnet.technic)
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