Subject:
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Re: A4 Class Locomotive teaser & Wheel count designations
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Newsgroups:
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lugnet.trains
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Date:
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Wed, 26 May 1999 00:29:06 GMT
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Viewed:
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718 times
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In lugnet.trains, Doug Glasnapp writes:
> I have completed my first atempt at creating the British A4 Loco.
> It's the streamlined A4 class british loco steam 4-6-2. I have the
> pictures developed, and my the redesign of my site is almost complete.
> Once i get the pics scanned, i will finish up the site and let everyone
> know about it. Should be done by this weekend.
I look forward to seeing it.
> I saw on J. Mathis page
> that he used the ball and sockets to make it work, and allowing the
> center set of wheels to slide perpendicular to the tracks. (its the one
> green wagons with tri-axles) I just want clarify that the two outer
> axles are able to rotate, and are connected to the center axle with the
> ball & socket, and the center axle is just designed to slide in the 1x2
> holes in the wagon plate? Would this work on a longer plate
> dimesnions? The composite plate dimensions are now 6x30, with the whole
> loco actually 6x32, but im planning on making it a tad longer. Is there
> any more clarification I would need or am I all set?
Correct: the two end wheelset pivot and the central wheelset translates
perpendicular to the track. However, the central wheelset can actually pivot
to some degree. I believe that the photos at my website show there to be two
red 1x1 tiles protruding into the two 1x2 'slots' in a black 6x24 train
baseplate (ie, from set 4552, crane wagon). Those really aren't necessary. In
fact, they prevent the middle wheelset from pivoting as much as it could. I
have since removed them from the model. Having the the slide in the 1x2 holes
in the wagon plate was an artifact left over from a design I used BEFORE
linking the wheelsets with the ball-and-socket.
I haven't tried to increase the separation between the wheelsets joined by the
ball-and-socket linkage. The following are just some thoughts about what might
be a problem.
Think in circles: Specificly, the circle that is a LEGO train track circle. The
greater the separation between the wheelsets, the greater must be the angle
between the two axles. A consequence for the middle wheelset is that it must
have greater translational freedom for larger axle separations.
The ludicrous extreme is a wagon plate that is equal in length to the diameter
of a LEGO train circle! Put the outer wheelsets at the ends of this way too
long wagon plate with a central wheelset at the midpoint of the wagon plate.
OK? Place this hypothetical way to long train on a LEGO train track circle:
So, the two outer wheelsets are opposite one another across a diameter of the
circle of track, and the middle wheelset is at a mid-point along a semi-circle
of the circle of track. OUCH! The two end wheelsets are at 180 degrees with
respect to one another (90 degrees with respect to the wagon plate; the wagon
plate crosses a diameter of the circle of track.), and they are at 90 degrees
with respect to the middle wheelset axle. A line drawn between an end wheelset
and the central wheelset makes a 45 degree angle with respect to either axle.
Now, think triangles: as the long wagon is put through the track curve,
the central wheelset translates. This results in an increase in the
axle-to-axle distance between the end wheelsets and the central wheelset. For
the wagons I built using the ball-and-socket linkage, there was enough 'slop'
in the ball-and-socket to accommodate this increased separation due to
translation of the central wheelset. I'm not sure there would be enough slop
in the ball-and-socket for an even longer wheelset separation.
I now this is extreme, but it just shows what wheelset separation limitation
may be encountered with the tri-axle ball-and-socket linkage as one tries to
build longer and longer wagons.
Give it a go! And, come up with something better! LEGO is so awesome for
this means of mechanical exploration, creativity, and problem-solving.
Sorry if my ramblings are unintelligible.
Have fun! I'm looking forward to seeing this Great Brit. Loco. :-)
later,
James Mathis
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Message has 2 Replies:
 | | Re: A4 Class Locomotive teaser & Wheel count designations
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| On the contrary, this isn't ludicrous at all. It's a great idea! Why hasn't it been done before. Build a circle of track with sixteen sections of track. Make a train car using four train motors separated by 90 degrees each. Fill in the entire middle (...) (25 years ago, 26-May-99, to lugnet.trains)
| | | Re: A4 Class Locomotive teaser & Wheel count designations
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| <snip> (...) Easy there, cowboy! I have built some 8 stud wide coaches (built over *2* wagon plates) that practically *do* equal the length of the diameter of the circle. *Looks* goofy going around the circle, and prototypically an engine could (...) (25 years ago, 26-May-99, to lugnet.trains)
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Message is in Reply To:
| | A4 Class Locomotive teaser & Wheel count designations
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| I have completed my first atempt at creating the British A4 Loco. It's the streamlined A4 class british loco steam 4-6-2. I have the pictures developed, and my the redesign of my site is almost complete. Once i get the pics scanned, i will finish (...) (25 years ago, 25-May-99, to lugnet.trains)
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