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Hi, first post. I'm new here.
I haven't been able to mentally sort out some issues with technic cars with
suspension, drive and steering without using specialist parts from sets like
8880.
Suspension--
Using wishbone suspension, the wheels moves outwards (or inwards depending on
your setup) relative to the ground (and car) when it travels over a bump. The
friction this causes can limit the effectiveness of the suspension, especially
when the car has done a jump which would cause all four wheels to push out (or
in) and if there is enough grip the suspension might not work at all resulting
in a thud.
A way of limiting this effect would be extending the length of the wishbones,
any other ideas?
Also, i have seen people use the air pistons for suspension (usually height
adjustable), but i haven't seen this done yet, and if it works it just might be
the best lego suspension possible. (this technology was banned from rally cars
after citreon started using it and won everything) Once it's set up it
apparently doesn't need tinkering electronic or otherwise.
http://www.kinetic.au.com/techno.html
H2 looks the easiest to set up, I'm not sure what is happening in the center of
the X system, i'll find out when i can.
Steering--
In real cars the wheel on the outside of the turn doesn't need to turn as much
to follow the curve. I haven't seen any lego devices to accommodate for this. It
also causes undue friction when turning. Perhaps it's beneficial given that it's
hard to make the center of wheel rotation close to the wheel base, so we have
that increased turning ability from the overs-steared outer wheel. Are there any
ways of making it better?
Drive--
I've had a look at lots of differentials which help to provide power to both
wheels even when one is off the ground, but all of them seem to cause friction
outside of that which comes with extra gears. Are there any simple mechanisms
that would force both wheels to turn within a ratio of each other, but in a
reversible fashion? Like a locked differential but with a designed amount of
frictionless give. Say Wheel1/wheel2 80%/120% or in the other extreme 120%/80%.
It should be designed with just enough give in either direction to allow the car
to turn.
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> Steering--
>
> In real cars the wheel on the outside of the turn doesn't need to turn as much
> to follow the curve. I haven't seen any lego devices to accommodate for this. It
> also causes undue friction when turning. Perhaps it's beneficial given that it's
> hard to make the center of wheel rotation close to the wheel base, so we have
> that increased turning ability from the overs-steared outer wheel. Are there any
> ways of making it better?
The 8880 Supercar has all-wheel steering so that both rear wheels turn less than
the front ones. That's not quite the same as Ackerman correction, but it helps.
I've seen Ackerman steering correction done in LEGO, but of course I can't find
it now that I'm trying to look for it specifically. It might have been in one of
those older "building robots using LEGO and the RCX"-type books.
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Hello,
Some examples using ackerman principle:
8860 technic car chassis
8479 barcode truck
8859 tractor
8462 tow truck
If you look further you will find many more.
Greetings
Maico Arts
Jordan Bradford schreef:
> > Steering--
> >
> > In real cars the wheel on the outside of the turn doesn't need to turn as much
> > to follow the curve. I haven't seen any lego devices to accommodate for this. It
> > also causes undue friction when turning. Perhaps it's beneficial given that it's
> > hard to make the center of wheel rotation close to the wheel base, so we have
> > that increased turning ability from the overs-steared outer wheel. Are there any
> > ways of making it better?
>
>
> The 8880 Supercar has all-wheel steering so that both rear wheels turn less than
> the front ones. That's not quite the same as Ackerman correction, but it helps.
>
> I've seen Ackerman steering correction done in LEGO, but of course I can't find
> it now that I'm trying to look for it specifically. It might have been in one of
> those older "building robots using LEGO and the RCX"-type books.
>
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