Subject:
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Re: I think it's time for a motor grader! Future 8455?
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Newsgroups:
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lugnet.technic
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Date:
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Thu, 18 Jan 2001 12:47:45 GMT
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Viewed:
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2069 times
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That Komatsu motor grader looks really cool, but it's not the coolest model
around. There are Caterpillar and Case graders around, and some older
models of graders still around have the ability to swing the blade to either
side. This is done by means of a short hydraulic piston which slots into a
hole. There are usually five holes arranged on a roughly U-shaped steel
column behind the blade assembly. This is usually done to grade a slope on
the side of a cut through a hill, or to drill out excess dirt next to a
gutter, or to make a deep cut for a channel that funnels water from the
roadway or construction site.
I think on most models the blade is simply put on the ground, then the
pistons that usually control blade pitch are used to lever the position of
the hydraulic piston at the hole slots over to the correct position for the
desired grading angle. The piston is withdrawn and inserted before and
after performing this operation, respectively.
One interesting thing to note is that the bigger the grader, the more power
it will usually have. Sometimes you'll find a grader which has a
hydraulically operated turntable motor for the blade. This usually is a
pair of cylinders, and there is some complex gizmo in front of it that feeds
the hydraulic fluid to the pistons, that are set in an opposing fashion.
Graders don't normally come with two sets of grader blades, usually there
are ripper claws on the back. Small rippers for ripping roadway and
loosening dirt so it can be drilled aside, and larger rippers for handling
the occasional deep ripping job or for ripping out an occasional tree.
Some really old models even had long ripping claws mounted in front on or
over the turntable assembly, specially designed for ripping out trees and
perhaps medium-large boulders. I wish I could find a site about graders in
general. There must be one or two out there, the earthmoving industry is
HUGE these days.
An interesting point to note is that even on the Komatsu grader pictured,
the main hydraulic pistons are (a) a lot bigger than other pistons, almost
as big as the ones found on larger earthmovers and (b) that they are mounted
with the pivot point at the extending end instead of the anchor end one
would usually expect them to be mounted at. There is also a traversing
piston which could probably be used to put the blade out to one side,
although I have not seen the Komatsu grader in operation, so cannot say for
sure.
One ability of graders that I'm particularly interested in is the ability to
swing around in a small almost 360 degree turning circle fairly quickly.
This is usually achieved by means a combination of pitched front wheels and
additional steering pistons at the juncture between the main supporting beam
that extends out and down to hold the front wheels, and the cab chassis,
usually containing the main power plant section, which is usually four-wheel
drive. It is quite amazing to watch a relatively large grader swing around
with such ease.
They also use the principle of front wheel pitch - and I do believe that I
have never seen a model with powered front wheels yet - to control the
movement of the grader when grading, and also when performing that turning
maneuver. It's really interesting to watch any grader in operation on a
road construction project.
I sure hope that any LEGO grader would incorporate these ideas into a model
grader. I will say that the resulting model will be quite complex, though.
It could easily blow out to around the 1000 piece mark. Also, they would
probably need to make a suitable blade part for the grader - nothing I have
yet seen would really be usable for a grader blade ...
Of course, if LEGO don't come up with a grader incorporating all these
functions, I think I'll have a go at it myself! :-) I just hope they come
up with a suitable blade piece!! I don't mind if the turntable turns around
pneumatically or not, I can handle that either way, as there are lots of
models that use a motor driven by electricity or hydraulics as well.
One thing I would wish for is to see a pneumatic control add-on module for
the Mindstorms system. I believe it could be done, and I believe that
making a small compressor unit that is powered by batteries or mains power
could be quite feasible. For obvious reasons, though, I think it should be
mains powered. Might need a long extension cord though. :-)
It should have an accessory system consisting of pressure sensors, so that
one could read the pressure in the tanks, and perhaps a feedback-control
loop of some kind that limits the amount of back-flow that can happen in
pneumatics. Going up requires a LOT of air pressure on most models, while
going down usually is all the way in little more than an eyeblink!!
Fine and coarse control of air flow would be nice, but I'm not sure how much
developing this all at once would cost. Maybe they are developing it
anyway. I sure hope they at least try their hand at a grader, it will be an
interesting model, and will teach their designers a thing or two about
really putting the challenge back into designing a good quality Technic
model!!
--
Cheers ...
Geoffrey Hyde
Bastonnade <TBouvart@aedifica.com> wrote in message
news:G7BtwB.J0o@lugnet.com...
> Hello Lego Technic fans. Since the 1997 front end loader (8459), lego • hasn't
> offered a large construction technic set. I think it would be a good idea • to
> make a motor grader:
>
> 1) Pneumatic blade control
> 2) 4 or all wheels drive
> 3) powerfull engine
> 4) Pivotting front wheel (like the real model) and direction.
> 5) Back blade if possible
> 6) Many more possible
>
> This one could be set 8455!
>
> Look at that!!!
> http://www.komatsugraders.com/graders/gd650.cfm
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Message has 1 Reply:
 | | Re: I think it's time for a motor grader! Future 8455?
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| (...) I'll second this! While I've yet to get the Mindstorms set, electrically controlled pneumatic switches would open up so many possibilities. While it is possible at the moment with various mechanisms, the motor overhead (and size) makes it (...) (24 years ago, 18-Jan-01, to lugnet.technic)
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Message is in Reply To:
| | I think it's time for a motor grader! Future 8455?
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| Hello Lego Technic fans. Since the 1997 front end loader (8459), lego hasn't offered a large construction technic set. I think it would be a good idea to make a motor grader: 1) Pneumatic blade control 2) 4 or all wheels drive 3) powerfull engine 4) (...) (24 years ago, 17-Jan-01, to lugnet.technic)
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