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Subject: 
Re: a most splendid 4x4
Newsgroups: 
lugnet.general, lugnet.technic
Date: 
Wed, 24 Oct 2001 21:12:34 GMT
Viewed: 
781 times
  
In lugnet.general, Allan Portillo writes:
The steering was not impresive. It had a tunring circle of 1.62 meters. The
worm gears in the axles meant that I could use fewer gears in gearing it
down. This decreased the amount of play in the complete transmission and so
starts climbing as soon as it hits an obsticle. In first and second gear it
would climb slopes as steep as 68 degrees, at which point it's front wheels
lifted and it would roll end over end down the slope. Those wheels are just
so grippy. In third gear it would climb a 63 degree slope at its maximum. On
a 64 degree slope, it would make it 1 time out of 3.

Now lets see. 63 degrees is 0.7 of a full right angle and it weighs 4.5
kilograms. 4.5 multiplied by 0.7 is 3.213 kilograms of tractive effort. This
is the power it has to go forward ( I think ). At this point the motors just
stop with a twitch or two every now and then.

I might be wrong, but if your incline is at 63 degrees, then the component
of force (force being the weight of your model) along the inclined surface
is = 4.5*sin(63) = 4.0 kg. That is the force, or pull, your model is
generating in a "forward" direction in 3rd gear.

However, I would use the 1st gear case on a 68 degree incline for this
calculation. Your model wasn't stable, but the motors didn't lock up, right?
Therefore the force is = 4.5*sin(68) = 4.2 kg.

But I'd bet your model can pull much more than 4.2 kg!

Anyway, very nice model! I enjoy a good 4x4 and yours is an excellent model.
What's even better is that you've built solid axles instead of independent
suspension. That's more like a real heavy-duty 4x4.

In fifth gear it can travel 1.18 meters per second.

=4.2 kph, 2.6 mph

That's probably faster than most people walk! Impressive for a large Lego model.

TJ



Message has 1 Reply:
  Re: a most splendid 4x4
 
(...) You should have saw the weird looks I got when I was walking down the street with it. I spotted a women in a bus shelter with a dog next to her sleeping. So what did I go and do. I drove over the dog, boy did it jump (smirk)8-). This top speed (...) (23 years ago, 25-Oct-01, to lugnet.general, lugnet.technic)

Message is in Reply To:
  Re: a most slendid 4x4
 
(...) The steering was not impresive. It had a tunring circle of 1.62 meters. The worm gears in the axles meant that I could use fewer gears in gearing it down. This decreased the amount of play in the complete transmission and so starts climbing as (...) (23 years ago, 24-Oct-01, to lugnet.general, lugnet.technic)

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