Subject:
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Re: Road grader ready for BrickFest
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Newsgroups:
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lugnet.technic
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Date:
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Mon, 21 Aug 2006 23:29:17 GMT
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Viewed:
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13022 times
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In lugnet.technic, Nathan Bell wrote:
> After about 3 blade designs and several overhauls, my grader design is complete.
> It was the hardest pneumatic design I have ever done because the amound to space
> for pneumatic lines and hoses was limited. There was also a few mechanical,
> structural, and flexibility issues to be addressed.
>
> http://www.brickshelf.com/cgi-bin/gallery.cgi?f=148840
>
> The blade had to be able to have 3 axes of freedom- which is commonly done with
> a ball-and-socket joint. Since Lego does not make any joints like that that can
> be pulled on with great force, I decided to make a 3-axes joint in front of the
> blade to take this force. It looks like it would pull out at the bottom, but it
> doesn't. I recently realized after looking closely at real graders that the
> blade assembly needs to be able to swing sideways. Up till that point I had the
> blade fixed so it could only move up straight. I also wanted to be able to steer
> from the cab with hand-of-god steering on the outside.
>
> The tilt steering was even harder to address because I had to fit pneumatic
> hoses inside the front suspension and figure out a way to route the system
> around the wheels so that they never brush up against the hoses. In reality, the
> steering system has a lot of friction and like any real life steering system- it
> works best when the vehicle/machine is already moving.
>
> 6 pneumatic switches were used and they seemed to look best in the cabin.
> Although they are not in the same places the switches are in real grader cabs, a
> 5" tall human could still operate everything from the cab if he could get around
> them. Anybody know any 5" tall humans?
>
> The rear tilting suspension is not the prettiest to look at but it works
> reasonably well. The wheels naturally want to pull outward when it makes turns
> but the old studded steering piece is there to hold the verticle suspension arms
> together. There was a lot of friction in the drivetrain so a white cluth gear
> had to be placed high in the drivetrain which is good if that long 12 stud-long
> crankshaft sags in the middle and becomes hard to turn.
>
> I had very few yellow technic parts so the black stripe down the side is to
> minimize yellow parts. It is not meant to look like any specific make of grader
> but it is about how I would make one look if I worked for Caterpillar.
>
> The blade does not turn 45 degrees, but the side-swing in the assembly allows it
> to turn about maybe 35 degrees.
>
> Overall the design is 26" (66cm) long. A few more small adjustments may need to
> be made, but it is so done that there is no reason to wait any longer to call it
> done.
>
> One might notice the "gap" in the bottom of the blade. I could not find any of
> those 1.5-stud wide track pieces that was 2-studs long, so I had to put an old
> Lego Town hinge there to fill the gap.
>
> The bent yellow beams on the outside of the chassis behind the blade are there
> to keep the chassis from breaking apart in front of the cab.
>
> Last but not least, the ripper does not have very long shanks but works well
> enough. It does not plunge all the way down to the shank frame, but I wanted it
> to elevate high enough for good grould clearance in the rear (which must not be
> too critical for graders since even a raised blade does not give very good
> ground clearance in the middle). Real blades might raise 18" (46 cm) off the
> ground according to the Caterpillar website.
>
> A thank you goes out to Alvin Brant (an another builder who's name I forgot) who
> explained the reason for grader wheels to tilt in detail.
>
> I am glad it is done and since I wanted it done before BrickFest I actually had
> to pray to God for help at one point. But He helped me think clearly in the
> nick of time!
>
> Enjoy the pics and don't hesitate at all to give comments or criticism as
> feedback.
>
> Nathan Bell
absolutly awsume there Nathan! right on.. i've operated a CAT14G motor grader
and the detail that you have ,+ mechanics is perfect.
you said that the rear wheels are not totally flat?.. send me a photo of what
you mean, i would be happy to take a boo at it if you like..
enjoy Brickfest.. wish i could be there..
in case your wondering, working on a turnpike truck right now**two dry vans back
to back with a converter and daycab..
take care, Glen Bell bellcapitol@shaw.ca
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Message has 1 Reply:
 | | Re: Road grader ready for BrickFest
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| (...) Its good to hear from you Glen! I said that when the grader turns, that the rear wheels want to pull apart at the bottom due to the twisting forces on them, but no they are not flat. I tried to make it look and work just like the real thing, (...) (18 years ago, 22-Aug-06, to lugnet.technic)
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Message is in Reply To:
| | Road grader ready for BrickFest
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| After about 3 blade designs and several overhauls, my grader design is complete. It was the hardest pneumatic design I have ever done because the amound to space for pneumatic lines and hoses was limited. There was also a few mechanical, structural, (...) (18 years ago, 21-Aug-06, to lugnet.technic)
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