Mopzilla
Posts: 632
Joined: 2/5/2002
From: Cupertino,
CA, USA
Status: offline
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I have been lurking for a while, but I'd like to share some ideas for nitro crawlers:
Rolling in neutral:
To solve the rolling backwards or forwards in neutral problem, you could mechanically mix in some brake at neutral, with a high idle. This is great as long as the brakes aren't grippy, because then it would be like an auto tranny. At neutral the car is slow but moves just a bit forward, stepping on the gas eliminates any braking, and stepping on the brakes further reduces the idle to full brakes.
In short, the throttle range and braking range overlap slightly from the throttle's idle to just enough to catch onto the clutch. That little grey area.
Now for different speeds:
Planetary gearsets are great... they are strong, simple, and have many ratios in a small package. If you put two planetary gearsets in a row, you could have a 4-speed with reverse, like some autos. You would need a small computer (robot BASIC STAMP controller?) to control the brakes on some of the gears. Maybe have a third channel with a 3 pos switch, pos 1 for reverse, pos 2 for rock crawling (like the "2" setting on autos) and pos 3 for ability to use all 4 gears. This would go real well with a powerful 4-stroke and the brake/clutch overlapping as described above.
With all this, you'd have to be ready for it to cost a lot... say, $150 engine/clutch, 2 planetary gearsets maybe $50, brakes another $25, and the micro controller for the auto tranny probably another $50. So you'd be approaching $300 just for the drivetrain.
On the bright side, you transmission would be so long that if you positioned the output of it in the center chassis, the engine could be above the front axle like in real trucks..
Just some ideas. If I had the money and most importantly, the TIME, I would go for it.
You could always hook up a Savage transmission with 3-speed, but it won't offer the SUPER WIDE scope of ratios as a 4-speed dual planetary geared e-controlled auto.
Edit: Actually, I thought it over with the 4-speed and planetary gears, and it would be kinda hard to pull off that much, since it's hard to do the clutches like they do in real cars.
< Message edited by Mopzilla -- 9/29/2006 7:13:44 PM >
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All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> RC Rock Crawlers >> RE: Nitro Rock Crawlers Only 
RE: Nitro Rock Crawlers Only - 
Just if noone found out yet.
