Subject:
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Re: New Parts Drawings - Plates, Slope, Track Pieces
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Newsgroups:
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lugnet.parts.custom
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Date:
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Fri, 11 Feb 2005 17:58:36 GMT
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Viewed:
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8238 times
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In lugnet.parts.custom, Walter Geissmann wrote:
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In lugnet.parts.custom, Mark Bellis wrote:
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I wish TLC would make these parts. Seeing earlier discussions I think I’m
not alone!
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Mark,
You’re not alone. There are a lot of people with part wishes.
Sorry, I don’t have drawings but I also have a lot of wishes for TLC.
I would like to have additional technic gears (with 10, 14, 18, 22, 28 and 32
teeth). I know I can realize nearly every gear ratio with the use of several
more gears, but the price is a lot more friction! Also I would like gears
with 18, 20, 22 and 24 teeth and with clutch. At the moment I cut
differentials to have at least a gear with 24 teeth and clutch. But the most
wanted parts (because there is no alternative solution) would be ring gears
with 24, 32, 40 and 48 teeth, because that would allow not only to build
simple planetary gear trains but also Simpson or Ravigneaux gear trains.
Walter
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In 1997 I sent TLC a sketch of some parts I wanted them to make, including 12
and 20 tooth cogs. Lo and behold the cogs appeared in the Droid Developer Kit
in 1999!
I had decided that 12:20 would mesh in the same holes as 16:16 and 8:24 for
gearboxes, which is why I suggested those sizes, apart from them being half way
between the existing ones. This was in the days when the test car 8865 used
16:24 at an angle, and I wanted to make gear ratios approximately 1.6:1 apart.
This was then developed in the Supercar 8880.
A mountain bike could be made with gears of 13, 15, 17, 19, 22, 25, 28 and 32
teeth, but if TLC made those, the bike would be far too wide, plus the cogs
would be made as bevels without chain compatibility :-(
I can understand why pairs of 10:22 and 14:18 might be useful, but anything
smaller than 8 would have to include the axle as part of the cog.
28 teeth are on the original differential gear and, yes, 32 teeth would be good
because it would mesh with 16 tooth cogs in the same beam or 8, 24 and 40 with a
half stud offset beam. The 32-tooth cog would have to be made chain compatible
though.
Perhaps planetary gears are a bit complex for Lego applications such as trucks,
since the scale of the gearbox would be too big for the wheel size, unless some
wheels bigger than 82mm were produced. Then there’s the torque capabilty of the
axles to consider of course. I’ve twisted a few myself!
I did have a go at an automatic gearbox, using differentials and an
unconventional layout. This was before the large turntable had appeared, but
the 24 toth ring in the turntable would make this easier with three 8-tooth cogs
in it, supported in a technic plate with holes on the top of the turntable.
Then the sun wheel is the middle cog, the planet set is the outer cog of the
turntable and the annulus is the bottom of the turntable.
More gears with round centre holes would be useful for making clocks. At the
moment, ratios of 2, 2, 3 and 5 are needed to get the 60:1 reduction in speed,
driving the second hand on the axle and the minute hand on a technic 1-wide
plate meshed with a 16-tooth cog with dog-clutch.
An alternative to cogs is to make a variable speed gearbox. I made a MOC of one
(no pics yet), based on one that was being developed for a car. The gearbox
consists of two haves of an axial ball race with three wheels inside the race
(instead of ball bearings) that do not rotate with the race. The three wheels
can be angled to vary the ration between the two halves by a factor of 9:1. One
half connects to the car engine and the other to the final drive. My MOC
couldn’t use ball races as that would require new moulds, but I used two flat
plates of tiles with the axles sprung to take up any slack when the wheels were
turned. The wheels were 24mm pulleys with tyres, and I used two rather than
three for easier angles. It’s good enough to demonstrate the principle but
can’t really transmit any power. The idea is that a computer keeps the engine
at maximum power (more efficient) and varies the angle of the wheels depending
on engine speed, driver command and load from the wheels.
Mark
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Message is in Reply To:
 | | Re: New Parts Drawings - Plates, Slope, Track Pieces
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| (...) Mark, You’re not alone. There are a lot of people with part wishes. Sorry, I don't have drawings but I also have a lot of wishes for TLC. I would like to have additional technic gears (with 10, 14, 18, 22, 28 and 32 teeth). I know I can (...) (19 years ago, 5-Feb-05, to lugnet.parts.custom, FTX)
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